RULES FOR THE SURVEY AND CONSTRUCTION OF STEEL SHIPSCONTENTSPart CSR-B

COMMON STRUCTURAL RULES FOR BULK CARRIERSGENERAL PRINCIPLES ............................................................................................................................... 1
Section 1 APPLICATION ............................................................................................................................................ 1

Chapter 1

Section 2

VERIFICATION OF COMPLIANCE

Section 3

FUNCTIONAL REQUIREMENTS................................................................................................................ 11
GENERAL ARRANGEMENT DESIGN ....................................................................................................... 20

Section 4
Chapter 2........................................................................................................... 5.............................................................................................................. 8

SYMBOLS AND DEFINITIONS............................................................................................................. 20

Section 1

SUBDIVISION ARRANGEMENT

Section 2

COMPARTMENT ARRANGEMENT ......................................................................................................... 24
ACCESS ARRANGEMENT ....................................................................................................................... 29

Section 3

STRUCTURAL DESIGN PRINCIPLES ....................................................................................................... 37
Section 1 MATERIAL ................................................................................................................................................. 37

Chapter 3

Section 3

NET SCANTLING APPROACH ................................................................................................................. 48
CORROSION ADDITIONS ........................................................................................................................ 51

Section 4

LIMIT STATES

Section 5

CORROSION PROTECTION

Section 2........................................................................................................................................... 53..................................................................................................................... 55

STRUCTURAL ARRANGEMENT PRINCIPLES ...................................................................................... 58
DESIGN LOADS ............................................................................................................................................ 87

Section 6
Chapter 4.................................................................................................................................................. 87

Section 1

GENERAL

Section 2
Section 3

SHIP MOTIONS AND ACCELERATIONS ................................................................................................ 88
HULL GIRDER LOADS ............................................................................................................................. 91

Section 4

LOAD CASES

Section 5

EXTERNAL PRESSURES

Section 6

INTERNAL PRESSURES AND FORCES ................................................................................................. 110
LOADING CONDITIONS ......................................................................................................................... 119

Section 7............................................................................................................................................ 97......................................................................................................................... 100

LOADING MANUAL AND LOADING INSTRUMENT ........................................................................... 125
Appendix 1 HOLD MASS CURVES ......................................................................................................................... 130
Section 8

Appendix 2 STANDARD LOADING CONDITION FOR DIRECT STRENGTHANALYSIS ............................................................................................................................................. 137
Appendix 3 STANDARD LOADING CONDITION FOR FATIGUE ASSESSMENT ................................................ 147
Chapter 5 HULL GIRDER STRENGTH ....................................................................................................................... 150................................................................................................................................... 150

Section 1

YIELDING CHECK

Section 2

ULTIMATE STRENGTH CHECK............................................................................................................. 160

Appendix 1 HULL GIRDER ULTIMATE STRENGTH ............................................................................................. 162
Chapter 6 HULL SCANTLINGS ................................................................................................................................... 173................................................................................................................................................... 173

Section 1

PLATING

Section 2

ORDINARY STIFFENERS

Section 3

BUCKLING & ULTIMATE STRENGTH OF ORDINARY STIFFENERS AND
STIFFENED PANELS ................................................................................................................................ 202

Section 4

PRIMARY SUPPORTING MEMBERS........................................................................................................................ 185...................................................................................................... 216

Appendix 1 BUCKLING & ULTIMATE STRENGTH ............................................................................................... 229
Chapter 7 DIRECT STRENGTH ANALYSIS ............................................................................................................... 235
Section 1

DIRECT STRENGTH ASSESSMENT OF THE PRIMARY SUPPORTING
MEMBERS ................................................................................................................................................ 235

Section 2

GLOBAL STRENGTH FE ANALYSIS OF CARGO HOLD STRUCTURES－Ⅰ－............................................ 237

DETAILED STRESS ASSESSMENT ......................................................................................................... 245
HOT SPOT STRESS ANALYSIS FOR FATIGUE STRENGTH ASSESSMENT ........................................ 249

Section 3
Section 4.................................................... 255

Appendix 1

LONGITUDINAL EXTENT OF THE FINITE ELEMENT MODELS

Appendix 2

DISPLACEMENT BASED BUCKLING ASSESSMENT IN FINITE ELEMENTANALYSES ............................................................................................................................................ 257

FATIGUE CHECK OF STRUCTURAL DETAILS ..................................................................................... 261
Section 1 GENERAL CONSIDERATION .................................................................................................................. 261

Chapter 8

Section 2

FATIGUE STRENGTH ASSESSMENT..................................................................................................... 263

STRESS ASSESSMENT OF PRIMARY MEMBERS ................................................................................. 267
Section 4 STRESS ASSESSMENT OF STIFFENERS ............................................................................................... 270
Section 5 STRESS ASSESSMENT OF HATCH CORNERS ...................................................................................... 282
Section 3

CROSS SECTIONAL PROPERTIES FOR TORSION ............................................................................ 285
OTHER STRUCTURES ................................................................................................................................ 293

Appendix 1
Chapter 9

Section 1

FORE PART............................................................................................................................................... 293.................................................................................................................................................. 303

Section 2

AFT PART

Section 3

MACHINERY SPACE

Section 4

SUPERSTRUCTURES AND DECKHOUSES ........................................................................................... 316
HATCH COVERS ...................................................................................................................................... 321

Section 5
Section 6
Chapter 10................................................................................................................................ 310

ARRANGEMENT OF HULL AND SUPERSTRUCTURE OPENINGS .................................................... 340
HULL OUTFITTING .................................................................................................................................. 353

Section 2

RUDDER AND MANOEUVRING ARRANGEMENT .............................................................................. 353
BULWARKS AND GUARD RAILS ........................................................................................................... 384

Section 3

EQUIPMENT

Section 1............................................................................................................................................. 387

CONSTRUCTION AND TESTING ............................................................................................................ 400
Section 1 CONSTRUCTION ...................................................................................................................................... 400

Chapter 11................................................................................................................................................. 403

Section 2

WELDING

Section 3

TESTING OF COMPARTMENTS............................................................................................................. 411

ADDITIONAL CLASS NOTATIONS......................................................................................................... 415

Chapter 12
Section 1

GRAB ADDITIONAL CLASS NOTATION............................................................................................... 415

SHIPS IN OPERATION, RENEWAL CRITERIA ..................................................................................... 416
Section 1 MAINTENANCE OF CLASS .................................................................................................................... 416

Chapter 13

Section 2

ACCEPTANCE CRITERIA ........................................................................................................................ 417－Ⅱ－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 1)

RULES FOR THE SURVEY AND CONSTRUCTION OF STEEL SHIPSPart CSR-B

COMMON STRUCTURAL RULES FOR BULK CARRIERS

Chapter 1
Section 1

1.

GENERAL PRINCIPLESAPPLICATION

General

1.1
Structural requirements
1.1.1This Part applies to ships classed with the Society and contracted for construction on or after 1 April 2006 but
before 1 July 2015.
Note: The "contracted for construction" means the date on which the contract to build the ship is signed between
the prospective owner and the shipbuilder. For further details regarding the date of "contracted for construction",refer to IACS Procedural Requirement (PR) No.29.
1.1.2This Part applies to the hull structures of single side skin and double side skin bulk carriers with unrestrictedworldwide navigation, having length LCSR-B of 90 m or above.
With bulk carrier is intended sea going self-propelled ships which are constructed generally with single deck,
double bottom, hopper side tanks and topside tanks and with single or double side skin construction in cargo lengtharea and intended primarily to carry dry cargoes in bulk, excluding ore and combination carriers.
Hybrid bulk carriers, where at least one cargo hold is constructed with hopper tank and topside tank, are coveredby this Part. The structural strength of members in holds constructed without hopper tank and/or topside tank is tocomply with the strength criteria defined in this Part.
1.1.3
This Part contains the IACS requirements for hull scantlings, arrangements, welding, structural details, materials
and equipment applicable to all types of bulk carriers having the following characteristics:
・ LCSR-B < 350 m
・ LCSR-B / B > 5
・ B / D < 2.5
・ CB ³ 0.6
1.1.4
This Part s requirements apply to welded hull structures made of steel having characteristics complying withrequirements in Ch 3, Sec 1. The requirements apply also to welded steel ships in which parts of the hull, such as
superstructures or small hatch covers, are built in material other than steel, complying with requirements in Ch 3, Sec1.
1.1.5
Ships whose hull materials are different than those given in 1.1.4 and ships with novel features or unusual hull
design are to be individually considered by the Society, on the basis of the principles and criteria adopted in this Part.
1.1.6
The scantling draught considered when applying this Part is to be not less than that corresponding to the assigned
freeboard.

－1－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 1)

1.1.7
Where scantlings are obtained from direct calculation procedures which are different from those specified in Ch 7,
adequate supporting documentation is to be submitted to the Society, as detailed in Sec 2.
1.2
Limits of application to lifting appliances
1.2.1
The fixed parts of lifting appliances, considered as an integral part of the hull, are the structures permanently
connected by welding to the ship s hull (for instance crane pedestals, masts, king posts, derrick heel seatings, etc.,
excluding cranes, derrick booms, ropes, rigging accessories, and, generally, any dismountable parts), only for thatpart directly interacting with the hull structure. The shrouds of masts embedded in the ship s structure are considered
as fixed parts.
1.2.2
The fixed parts of lifting appliances and their connections to the ship s structure are to be accordance with therelevant requirements of the Rules for Cargo Handling Appliances, irrespective of the registration of such cargohandling appliances.
1.2.3
The design of the structure supporting fixed lifting appliances and the structure that might be called to support amobile appliance should be designed taking into account the additional loads that will be imposed on them by theoperation of the appliance as declared by the shipbuilder or its sub-contractors.
1.3
Limits of application to welding procedures
1.3.1
The requirements of this Part apply also for the preparation, execution and inspection of welded connections inhull structures.
Issues relating to the preparation, execution and inspection of welded connections in hull structures other thanthose specified in this Part, are to be in accordance with the general requirements relevant to fabrication by welding
and qualification of welding procedures as specified in Part M.
2.

Rule application

2.1
Ship parts
2.1.1 General
For the purpose of application of this Part, the ship is considered as divided into the following three parts:
・ fore part・ central part・ aft part.
2.1.2 Fore part
The fore part includes the structures located forward of the collision bulkhead, i.e.:・ the fore peak structures
・ the stem.
In addition, it includes:
・ the reinforcements of the flat bottom forward area
・ the reinforcements of the bow flare area.
2.1.3 Central partThe central part includes the structures located between the collision bulkhead and the after peak bulkhead.
Where the flat bottom forward area or the bow flare area extend aft of the collision bulkhead, they are considered
as belonging to the fore part.
2.1.4 Aft part
The aft part includes the structures located aft of the after peak bulkhead.
2.2
Rules applicable to various ship parts
2.2.1
The various chapters and sections are to be applied for the scantling of ship parts according to Table 1.

－2－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 1)

Table 1

Chapters and sections applicable for the scantling of ship parts
Applicable Chapters and Sections

Part
Fore part

GeneralSpecific
Ch 9, Sec 1

Ch 1
Ch 2

Central part

Ch 3

Ch 6

Ch 4

Ch 7
Ch 8

Ch 5
(1)

Ch 9 , excluding Ch 9, Sec 1 & Ch 9, Sec 2
Aft part

Ch 9, Sec 2

Ch 11(1) See also 2.3.

2.3
Rules applicable to other ship items
2.3.1
The various Chapters and Sections are to be applied for the scantling of other ship items according to Table 2.
Table 2

Chapters and sections applicable for the scantling of other items
Item

3.

Applicable Chapters and Sections

Machinery spaces

Ch 9, Sec 3

Superstructures and deckhouses

Ch 9, Sec 4

Hatch covers

Ch 9, Sec 5

Hull and superstructure openings

Ch 9, Sec 6

Rudders

Ch 10, Sec 1

Bulwarks and guard rails

Ch 10, Sec 2

Equipment

Ch 10, Sec 3

Class Notations

3.1
Additional service features BC-A, BC-B and BC-C
3.1.1
The following requirements apply to ships, as defined in 1.1.2, having length L of 150 m or above.
3.1.2
For bulk carriers, one of the following notations is to be affixed to the Classification Characters corresponding to
the following service features:a) BC-A: for bulk carriers designed to carry dry bulk cargoes of cargo density 1.0 t/m3 and above with specified
holds empty at maximum draught in addition to BC-B conditions.
b) BC-B: for bulk carriers designed to carry dry bulk cargoes of cargo density of 1.0 t/m3 and above with all cargoholds loaded in addition to BC-C conditions.
c) BC-C: for bulk carriers designed to carry dry bulk cargoes of cargo density less than 1.0 t/m3.
3.1.3
The following additional notations or descriptive notes are to be provided giving further detailed description oflimitations to be observed during operation as a consequence of the design loading condition applied during thedesign in the following cases:・ {maximum cargo density (in t/m3)}: Maximum cargo density is to be registered in the Classification Register as
descriptive notes for additional service features BC-A and BC-B, if the maximum cargo density is less than
3.0 t/m3 (see also Ch 4, Sec 7, 2.1).
・ {no MP}: The additional notation of (no MP) is to be affixed for all additional service features when the ship
has not been designed for loading and unloading in multiple ports in accordance with the conditions specified in
Ch 4, Sec 7, 3.3.

－3－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 1)・ {allowed combination of specified empty holds}: Allowable combination of specified empty cargo holds is to beregistered in the Classification Register as descriptive notes for additional service feature BC-A (see also Ch 4,
Sec 7, 2.1).
3.2
Additional class notation GRAB [X]
3.2.1 Application
The additional class notation GRAB [X] is mandatory for ships having one of the additional service features BC-A
or BC-B, according to 3.1.2. For these ships the requirements for the GRAB [X] notation given in Ch 12, Sec 1 are to
be complied with for an unladen grab weight X equal to or greater than 20 tons.
For all other ships the additional class notation GRAB [X] is voluntary.
3.3Class notation CSR
3.3.1 Application
In addition to the class notations granted by the assigning Society in accordance with the provisions of 1.2, Part A
and to the service features and additional class notations defined hereabove, ships fully complying with this Part will
be assigned the notation CSR.

－4－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 2)

Section 2
1.

VERIFICATION OF COMPLIANCE

General

1.1
New buildings
1.1.1
For new buildings, the plans and documents submitted for approval, as indicated in 2, are to comply with theapplicable requirements in Ch 1 to Ch 12 of this Part, taking account of the relevant criteria, as the additional service
features and classification notation assigned to the ship or the ship length.
1.1.2
When a ship is surveyed by the Society during construction, the Society:・ approves the plans and documentation submitted as required by the Rules
・ proceeds with the appraisal of the design of materials and equipment used in the construction of the ship andtheir inspection at works
・ carries out surveys or obtains appropriate evidence to satisfy itself that the scantlings and construction meet therule requirements in relation to the approved drawings
・ attends tests and trials provided for in the Rules
・ assigns the Classification Character of NS* .
1.1.3
The Society defines in specific Rules which materials and equipment used for the construction of ships built undersurvey are, as a rule, subject to appraisal of their design and to inspection at works, and according to which
particulars.
1.1.4
As part of his interventions during the ship s construction, the Surveyor will:・ conduct an overall examination of the parts of the ship covered by the Rules
・ examine the construction methods and procedures when required by the Rules
・ check selected items covered by the rule requirements
・ attend tests and trials where applicable and deemed necessary.
1.2
Ships in service
1.2.1
For ships in service, the requirements in Ch 13 of this Part are to be complied with.
2.

Documentation to be submitted

2.1
Ships surveyed by the Society during the construction
2.1.1 Plans and documents to be submitted for approval
For the application of this Part, the plans and documents to be submitted to the Society for approval are listed inTable 1. In addition, the Society may request for approval or information, other plans and documents deemednecessary for the review of the design.
Structural plans are to show details of connection of the various parts and are to specify the design materials,
including, in general, their manufacturing processes, welding procedures and heat treatments. See also Ch 11, Sec 2,
1.4.
2.1.2 Plans and documents to be submitted for information
For the application of this Part, in addition to those in 2.1.1, the following plans and documents are to be submitted
to the Society for information:
・ general arrangement
・ capacity plan, indicating the volume and position of the centre of gravity of all compartments and tanks
・ lines plan・ hydrostatic curves
・ lightweight distribution－5－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 2)

・ docking plan.
In addition, when direct calculation analyses are carried out by the Designer according to the requirements of thisPart, they are to be submitted to the Society (see 3).
2.2
Ships for which the Society acts on behalf of the relevant Administration
2.2.1 Plans and documents to be submitted for approval
The plans required by the National Regulations concerned are to be submitted to the Society for approval, in
addition to those in 2.1.
Table 1

Plans and documents to be submitted for approval

Plan or document

Containing also information on

Midship section

Class characteristics

Transverse sections

Main dimensions

Shell expansion

Minimum ballast draught

Decks and profiles

Frame spacing

Double bottom

Contractual service speed

Pillar arrangements

Density of cargoes

Framing plan

Design loads on decks and double bottom

Deep tank and ballast tank bulkheads,

washbulkheads

Steel grades
Corrosion protection
Openings in decks and shell and relevant compensations
Boundaries of flat areas in bottom and sides
Details of structural reinforcements and/or discontinuities
Bilge keel with details of connections to hull structures

Watertight subdivision bulkheads

Openings and their closing appliances, if any

Watertight tunnels
Fore part structure
Aft part structure
Machinery space structures

Type, power and rpm of propulsion machinery

Foundations of propulsion machinery and boilers

Mass and centre of gravity of machinery and boilers

Superstructures and deckhouses

Extension and mechanical properties of the aluminium alloy used

Machinery space casing(where applicable)

Hatch covers and hatch coamings

Design loads on hatch covers
Sealing and securing arrangements, type and position of locking bolts
Distance of hatch covers from the summer load waterline and from thefore end

Transverse thruster, if any, general arrangement,
tunnel structure, connections of thruster withtunnel and hull structures
Bulwarks and freeing ports

Arrangement and dimensions of bulwarks and freeing ports on the
freeboard deck and superstructure deck

Windows and side scuttles, arrangements anddetails
Scuppers and sanitary discharges
Rudder and rudder horn(1)Maximum ahead service speed

Sternframe or sternpost, sterntube
Propeller shaft boss and brackets(1)Plan of watertight doors and scheme of relevant

Manoeuvring devices

manoeuvring devices

Electrical diagrams of power control and position indication circuits

Plan of outer doors and hatchways－6－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 2)

Plan or document

Containing also information on

Derricks and cargo gear

Design loads (forces and moments)

Cargo lift structures

Connections to the hull structures

Sea chests, stabiliser recesses, etc.
Hawse pipes
Plan of manholes
Plan of access to and escape from spaces
Plan of ventilation

Use of spaces and location and height of air vent outlets of various
compartments

Plan of tank testing

Testing procedures for the various compartments
Height of pipes for testing

Loading manual and loading instruments
Equipment number calculation

Loading conditions as defined in Ch 4, Sec 7 (see also Ch 4, Sec 8)
Geometrical elements for calculation
List of equipment
Construction and breaking load of steel wires
Material, construction, breaking load and relevant elongation ofsynthetic ropes(1) Where other steering or propulsion systems are adopted (e.g. steering nozzles or azimuth propulsion systems), the plans
showing the relevant arrangement and structural scantlings are to be submitted. For azimuth propulsion systems, see Ch
10, Sec 1, 11.

3.

Computer programs

3.1
General
3.1.1
In order to increase the flexibility in the structural design direct calculations with computer programs are
acceptable (see Ch 7). The aim of such analyses is to assess the structure compliance with the requirements of this
Part.
3.2
General programs
3.2.1
The choice of computer programs according to currently available technology is free. The programs are to be able
to manage the model and load cases as required in Ch 7 and/or Ch 8. The programs may be checked by the Society
through comparative calculations with predefined test examples. A generally valid approval for a computer programis, however, not given by the Society.
3.2.2
Direct calculations may be used in the following fields:
・ global strength
・ longitudinal strength
・ beams and grillages
・ detailed strength.
3.2.3
For such calculation the computer model, the boundary condition and load cases are to be agreed upon with theSociety.
The calculation documents are to be submitted including input and output. During the examination it may provenecessary that the Society performs independent comparative calculations.

－7－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 3)

Section 3
1.

FUNCTIONAL REQUIREMENTS

General1.1
Application
1.1.1
This section defines the set of requirements relevant to the functions of the ship structures to be complied withduring design and construction, to meet the following objectives.
1.2
Design life
1.2.1
The ship is to remain safe and environment-friendly, if properly operated and maintained, for her expected design
life, which, unless otherwise specifically stated, is assumed to be equal to 25 years. The actual ship life may belonger or shorter than the design life, depending on the actual conditions and maintenance of the ship, taking into
account aging effects, in particular fatigue, coating deterioration, corrosion, wear and tear.
1.3
Environmental conditions
1.3.1
The ship s structural design is to be based on the assumption of trading in the North Atlantic environment for theentire design life. Hence the respective wave conditions, i.e. the statistical wave scatter takes into account the basic
principle for structural strength layout.
1.4
Structural safety
1.4.1
The ship is to be designed and constructed, and subsequently operated and maintained by its builders and operators,
to minimise the risk for the safety of life at sea and the pollution of the marine environment as the consequence of thetotal loss of the ship due to structural collapse and subsequent flooding, loss of watertight integrity.
1.5
Structural accessibility
1.5.1
The ship is to be designed and constructed to provide adequate means of access to all spaces and internal structures
to enable overall and close-up inspections and thickness measurements.
1.6
Quality of construction
1.6.1
As an objective, ships are to be built in accordance with controlled quality production standards using approved
materials as necessary.
2.

Definition of functional requirements

2.1
General2.1.1
The functional requirements relevant to the ship structure are indicated in 2.2 to 2.6.
2.2Structural strength
2.2.1
Ships are to be designed to withstand, in the intact condition, the environmental conditions during the design life,
for the appropriate loading conditions. Structural strength is to be determined against buckling and yielding. Ultimate
strength calculations have to include ultimate hull girder capacity and ultimate strength of plates and stiffeners.
2.2.2
Ships are to be designed to have sufficient reserve strength to withstand the wave and internal loads in damaged
conditions that are reasonably foreseeable, e.g. collision, grounding or flooding scenarios. Residual strength－8－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 3)

calculations are to take into account the ultimate reserve capacity of the hull girder, considering permanent
deformation and post-buckling behaviour.
2.2.3
Ships are to be assessed according to the expected design fatigue life for representative structural details.
2.3
Coating
2.3.1
Coating, where required, is to be selected as a function of the declared use of the ship spaces, e.g. holds, tanks,cofferdams, etc., materials and application of other corrosion prevention systems, e.g. cathodic protection or otheralternative means. The protective coating systems, applied and maintained in accordance with manufacturer s
specifications concerning steel preparation, coating selection, application and maintenance, are to comply with the
SOLAS requirements, the flag administration requirements and the Owner specifications.
2.4
Corrosion addition
2.4.1
The corrosion addition to be added to the net scantling required by structural strength calculations is to be adequate
for the operating life. The corrosion addition is to be assigned in accordance with the use and exposure of internal andexternal structure to corrosive agents, such as water, cargo or corrosive atmosphere, in addition to the corrosion
prevention systems, e.g. coating, cathodic protection or by alternative means.
2.5
Means of access
2.5.1
Ship structures subject to overall and close-up inspection and thickness measurements are to be provided withmeans capable of ensuring safe access to the structures. The means of access are to be described in a Ship Structure
Access Manual for bulk carriers of 20,000 gross tonnage and over. Reference is made to SOLAS, Chapter II-1,
Regulation 3-6.
2.6
Construction quality procedures
2.6.1
Specifications for material manufacturing, assembling, joining and welding procedures, steel surface preparationand coating are to be included in the ship construction quality procedures.
3.

Other regulations

3.1
International regulations
3.1.1
Attention of designers, shipbuilders and shipowners of ships covered by this Part is drawn on the following:
Ships are designed, constructed and operated in a complex regulatory framework prescribed internationally by
IMO and implemented by flag states or by classification societies on their behalf. Statutory requirements set thestandard for statutory aspects of ships such as life saving, subdivisions, stability, fire protection, etc.
These requirements influence the operational and cargo carrying arrangements of the ship and therefore may affectits structural design.
The main international instruments normally to be applied with regard to the strength of bulk carriers are:・ International Convention for Safety of Life at Sea (SOLAS)
・ International Convention on Load Lines
3.2
National regulations
3.2.1
Attention is drawn on the applicable national flag state regulations.
Compliance with these regulations of national administrations is not conditional for class assignment.

－9－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 3)

4.

Workmanship4.1
Requirements to be complied with by the manufacturer
4.1.1
The manufacturing plant is to be provided with suitable equipment and facilities to enable proper handling of thematerials, manufacturing processes, structural components, etc.
The manufacturing plant is to have at its disposal sufficiently qualified personnel. The Society is to be advised of
the names and areas of responsibility of the supervisory and control personnel in charge of the project.
4.2
Quality control
4.2.1
As far as required and expedient, the manufacturer's personnel has to examine all structural components bothduring manufacture and on completion, to ensure that they are complete, that the dimensions are correct and thatworkmanship is satisfactory and meets the standard of good shipbuilding practice.
Upon inspection and corrections by the manufacturing plant, the structural components are to be shown to thesurveyor of the Society for inspection, in suitable sections, normally in unpainted condition and enabling proper
access for inspection.
The Surveyor may reject components that have not been adequately checked by the plant and may demand theirre-submission upon successful completion of such checks and corrections by the plant.
5.

Structural Details

5.1
Details in manufacturing documents
5.1.1
Significant details concerning quality and functional ability of the component concerned are to be entered in the
manufacturing documents (workshop drawings, etc.). This includes not only scantlings but - where relevant - suchitems as surface conditions (e.g. finishing of flame cut edges and weld seams), and special methods of manufacture
involved as well as inspection and acceptance requirements and where relevant permissible tolerances. So far as forthis aim a standard is used (works or national standard etc.) it is to be submitted to the Society. For weld joint details,
see Ch 11, Sec 2.
If, due to missing or insufficient details in the manufacturing documents, the quality or functional ability of thecomponent is doubtful, the Society may require appropriate improvements to be submitted by the manufacturer. This
includes the provision of supplementary or additional parts (for example reinforcements) even if these were notrequired at the time of plan approval.

－10－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

Section 4
1.

SYMBOLS AND DEFINITIONS

Primary symbols and units

1.1
1.1.1
Unless otherwise specified, the general symbols and their units used in this Part are those defined in Table 1.
Table 1Primary symbols

SymbolMeaning

Units

Area

m2

Sectional area of ordinary stiffeners and primary members

cm2

B

Moulded breadth of ship (see [2])

m

A

C

Coefficient-D

Depth of ship (see [2])mEYoung s modulus

F

Force and concentrated loads

kN

Hull girder inertia

m4

Inertia of ordinary stiffeners and primary members

cm4

Length of ship (see [2])m

I

LCSR-B

N/mm2

M

Bending moment

kN-m

Q

Shear forcekN

S

Spacing of primary supporting membersmT

Draught of ship (see [2])mV

Ship s speed

knot

Z

Hull girder section modulus

m3aAccelerationm/s2

Width of attached plating

m

b
g
h

Width of face plate of ordinary stiffeners andprimary members

mm

Gravity acceleration (see [2])m/s2Heightm

Web height of ordinary stiffeners andprimary members

mmkMaterial factor (see [2])-lLength / Span of ordinary stiffeners and primary supporting members

m

m

Mass

t

n

Number of items-

p

PressurekN/m2

Radiusmm

Radius of curvature of plating or bilge radiusmrs

Spacing of ordinary stiffenersmt

Thicknessmmw

Section modulus of ordinary stiffeners and primary supporting members

cm3x

X coordinate along longitudinal axis (see [4])my

Y coordinate along transverse axis (see [4])mz

Z coordinate along vertical axis (see [4])mgdSafety factor-

Deflection / Displacement

mm

q

Angle

deg

－11－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

Symbol2.

MeaningUnitsx

Weibull shape parameter-r

Densityt/m3s

Bending stress

N/mm2

t

Shear stress

N/mm2

Symbols

2.1
Ship s main data
2.1.1
LCSR-B : Rule length, in m, defined in 3.1
LLL : Freeboard length, in m, defined in 3.2
LBP : Length between perpendiculars, in m, is the length of the ship measured between perpendiculars taken at theextremities of the deepest subdivision load line, i.e. of the waterline which corresponds to the greatest
draught permitted by the subdivision requirements which are applicable
FPLL : Forward freeboard perpendicular. The forward freeboard perpendicular is to be taken at the forward end of
the length LLL and is to coincide with the foreside of the stem on the waterline on which the length LLL is
measured.
APLL : After freeboard perpendicular. The after freeboard perpendicular is to be taken at the aft end of the length
LLL.
B: Moulded breadth, in m, defined in 3.4
D: Depth, in m, defined in 3.5
T: Moulded draught, in m, defined in 3.6: Scantling draught, in m, taken equal to the maximum draught (see also Ch 1, Sec 1, 1.1.6)
TS: Minimum ballast draught at midship, in m, in normal ballast condition as defined in Ch 4, Sec 7, 2.2.1
TB
TLC : Midship draught, in m, in the considered loading condition
D: Moulded displacement, in tonnes, at draught T, in sea water (density r = 1.025 t/m3): Total block coefficient
CB
Δ
CB =
1.025LCSR - B BT
V

: Maximum ahead service speed, in knots, means the greatest speed which the ship is designed to maintain inservice at her deepest seagoing draught at the maximum propeller RPM and corresponding engine MCR(Maximum Continuous Rating).
x, y, z : X, Y and Z co-ordinates, in m, of the calculation point with respect to the reference co-ordinate system.
2.2
Materials
2.2.1
E: Young s modulus, in N/mm2, to be taken equal to:
E = 2.06 * 105 N/mm2, for steels in general
E = 1.95 * 105 N/mm2, for stainless steels
E = 7.0 * 104 N/mm2, for aluminium alloys
ReH : Minimum yield stress, in N/mm2, of the materialk: Material factor, defined in Ch 3, Sec 1, 2.2n: Poisson s ratio. Unless otherwise specified, a value of 0.3 is to be taken into account,: Ultimate minimum tensile strength, in N/mm2, of the material
Rm: Nominal yield stress, in N/mm2, of the material, to be taken equal to 235/k N/mm2, unless otherwise
RY
specified.
2.3
2.3.1
G

r

Loads
: Gravity acceleration, taken equal to 9.81 m/s2
: Sea water density, taken equal to 1.025 t/m3

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

rL
rC
C

: Density, in t/m3, of the liquid carried: Density, in t/m3, of the dry bulk cargo carried: Wave parameter, taken equal to:
1.5æ 300 - LCSR - B ö
C = 10.75 - ç100è
ø
C = 10.75

for 90m £ LCSR- B < 300m
for 300m £ LCSR - B < 350mh

: Height, in m, of a tank, to be taken as the vertical distance from the bottom to the top of the tank,excluding any small hatchways: Vertical distance, in m, of the highest point of the tank from the baseline. For ballast holds, zTOP is thezTOPvertical distance, in m, of the top of the hatch coaming from the baseline: Length, in m, of the compartment
lH: Design still water bending moment, in kN-m, at the hull transverse section considered:MSW
in hogging conditions
MSW = MSW,Hin sagging conditions
MSW = MSW,S: Vertical wave bending moment, in kN-m, at the hull transverse section considered:
MWV
MWV = MWV,H in hogging conditions
in sagging conditions
MWV = MWV,S: Horizontal wave bending moment, in kN-m, at the hull transverse section considered,
MWH: Design still water shear force, in kN, at the hull transverse section considered
QSW: Vertical wave shear force, in kN, at the hull transverse section considered
QWV: Still water pressure, in kN/m2
pS
pW: Wave pressure or dynamic pressures, in kN/m2
pSF, pWF : Still water and wave pressure, in kN/m2, in flooded conditionssX: Hull girder normal stress, in N/mm2
aX, aY, aZ : Accelerations, in m/s2, along X, Y and Z directions, respectively: Roll period, in sTRq
: Roll single amplitude, in deg
TP: Pitch period, in sF
: Single pitch amplitude, in deg: Roll radius of gyration, in m
kr
GM
: Metacentric height, in ml
: Wave length, in m
2.4
Scantlings
2.4.1 Hull girder scantlings
IY: Moment of inertia, in m4, of the hull transverse section about its horizontal neutral axis
IZ
: Moment of inertia, in m4, of the hull transverse section about its vertical neutral axis
ZAB, ZAD : Section moduli, in m3, at bottom and deck, respectively
N: Vertical distance, in m, from the base line to the horizontal neutral axis of the hull transverse section
2.4.2 Local scantlingss : Spacing, in m, of ordinary stiffeners, measured at mid-span along the chord
S : Spacing, in m, of primary supporting members, measured at mid-span along the chordl : Span, in m, of ordinary stiffener or primary supporting member, as the case may be, measured along the chordlb : Length, in m, of brackets
tC : Corrosion addition, in mm
hw : Web height, in mm, of ordinary stiffener or primary supporting member, as the case may be
tw : Net web thickness, in mm, of ordinary stiffener or primary supporting member, as the case may be
bf : Face plate width, in mm, of ordinary stiffener or primary supporting member, as the case may be
tf : Net face plate thickness, in mm, of ordinary stiffener or primary supporting member, as the case may be
tp : Net thickness, in mm, of the plating attached to an ordinary stiffener or a primary supporting member, as thecase may be
bp : Width, in m, of the plating attached to the stiffener or the primary supporting member, for the yielding check－13－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

As : Net sectional area, in cm2, of the stiffener or the primary supporting member, with attached plating of width s
Ash : Net shear sectional area, in cm2, of the stiffener or the primary supporting member
I : Net moment of inertia, in cm4, of ordinary stiffener or primary supporting member, as the case may be, without
attached plating, around its neutral axis parallel to the plating
Ip : Net polar moment of inertia, in cm4, of ordinary stiffener or primary supporting member, as the case may be,
about its connection to plating
Iw : Net sectional moment of inertia, in cm6, of ordinary stiffener or primary supporting member, as the case may
be, about its connection to plating
IS : Net moment of inertia, in cm4, of the stiffener or the primary supporting member, with attached shell plating ofwidth s, about its neutral axis parallel to the plating
Z : Net section modulus, in cm3, of an ordinary stiffener or a primary supporting member, as the case may be, with
attached plating of width bp
3.

Definitions

3.1
Rule length
3.1.1
The rule length LCSR-B is the distance, in m, measured on the summer load waterline, from the forward side of thestem to the after side of the rudder post, or to the centre of the rudder stock where there is no rudder post. LCSR-B is tobe not less than 96% and need not exceed 97% of the extreme length on the summer load waterline.
3.1.2
In ships without rudder stock (e.g. ships fitted with azimuth thrusters), the rule length LCSR-B is to be taken equal to97% of the extreme length on the summer load waterline.
3.1.3
In ships with unusual stem or stern arrangements, the rule length LCSR-B is considered on a case by case basis.
3.2
Freeboard length
3.2.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 3(1,a))
The freeboard length LLL is the distance, in m, on the waterline at 85% of the least moulded depth from the top of
the keel, measured from the forward side of the stem to the centre of the rudder stock. LLL is to be not less than 96%
of the extreme length on the same waterline.
3.2.2
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 3(1,c))Where the stem contour is concave above the water-line at 85% of the least moulded depth, both the forward endof the extreme length and the forward side of the stem are to be taken at the vertical projection to that waterline of theaftermost point of the stem contour (above that waterline) (see Fig. 1).
Fig. 1

Concave stem contour

0.85 D

Forward terminal of
the total length－14－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

3.3
Ends of rule length LCSR-B and midship3.3.1 Fore end
The fore end (FE) of the rule length LCSR-B, see Fig. 2, is the perpendicular to the summer load waterline at theforward side of the stem.
The aft end (AE) of the rule length LCSR-B, see Fig. 2, is the perpendicular to the waterline at a distance LCSR-B aft of
the fore end.
Fig. 2Ends and midship

LCSR-B/2

LCSR-B/2
LCSR-B

3.3.2 Midship
The midship is the perpendicular to the waterline at a distance 0.5LCSR-B aft of the fore end.
3.3.3 Midship part
The midship part of a ship is the part extending 0.4LCSR-B amidships, unless otherwise specified.
3.4
Moulded breadth
3.4.1
The moulded breadth B is the greatest moulded breadth, in m, measured amidships below the weather deck.
3.5
Depth
3.5.1
The depth D is the distance, in m, measured vertically on the midship transverse section, from the moulded baseline to the top of the deck beam at side on the upper-most continuous deck.
3.6
Moulded draught
3.6.1
The moulded draught T is the distance, in m, measured vertically on the midship transverse section, from themoulded base line to the summer load line.
3.7
Lightweight
3.7.1
The lightweight is the displacement, in t, without cargo, fuel, lubricating oil, ballast water, fresh water and feedwater, consumable stores and passengers and crew and their effects.
3.8
Deadweight
3.8.1
The deadweight is the difference, in t, between the displacement, at the summer draught in sea water of density
r = 1.025 t/m3, and the lightweight.
3.9
Freeboard deck
3.9.1
Ref. ILLC, as amended (Resolution MSC. 143(77) Reg. 3(9))
The freeboard deck is defined in Regulation 3 of the International Load Line Convention, as amended.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

3.10
Bulkhead deck
3.10.1
Ref. SOLAS Reg.II-1/2 .5
The bulkhead deck is the uppermost deck to which the transverse watertight bulkheads, except both peakbulkheads, extend and are made effective.
3.11
Strength deck
3.11.1The strength deck at a part of ship s length is the uppermost continuous deck at that part to which the shell plates
extend.
3.12
Superstructure
3.12.1 General
Ref. ILLC. As amended (Resolution MSC.143(77) Reg. 3(10,a))A superstructure is a decked structure on the free-board deck, extending from side to side of the ship or with theside plating not being inboard of the shell plating more than 0.04B.
3.12.2 Enclosed and open superstructure
A superstructure may be:・ enclosed, where:
1) it is enclosed by front, side and aft bulkheads complying with the requirements of Ch 9, Sec 42) all front, side and aft openings are fitted with efficient weathertight means of closing
・ open, where it is not enclosed.
3.13
Forecastle
3.13.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 3(10,g))
A forecastle is a superstructure which extends from the forward perpendicular aft to a point which is forward of theafter perpendicular. The forecastle may originate from a point forward of the forward perpendicular.
3.14
Raised quarterdeck
3.14.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 3(10,i))A raised quarterdeck is a superstructure which extends forward from the after perpendicular, generally has a heightless than a normal superstructure, and has an intact front bulkhead (sidescuttles of the non-opening type fitted withefficient deadlights and bolted man hole covers)(see Fig. 3). Where the forward bulkhead is not intact due to doors
and access openings, the superstructure is then to be considered as a poop.
Fig. 3Raised quarter deck－16－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

3.15
Deckhouse
3.15.1
A deckhouse is a decked structure other than a superstructure, located on the freeboard deck or above.
3.16
Trunk
3.16.1
A trunk is a decked structure similar to a deckhouse, but not provided with a lower deck.
3.17
Wash bulkhead
3.17.1A wash bulkhead is a perforated or partial bulkhead in a tank.
3.18
Standard height of superstructure
3.18.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 33)
The standard height of superstructure is defined in Table 2.
Table 2Standard height of superstructure

Freeboard length LLL, in m

Standard height hS, in m
Raised quarter deck

All other superstructures

90 < LLL < 125

0.3 + 0.012 LLL

1.05 + 0.01 LLL

LLL ³ 125

1.80

2.30

3.19
Type A and Type B ships
3.19.1 Type A ship
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 27.1)
A Type A ship is one which:・ is designed to carry only liquid cargoes in bulk;
・ has a high integrity of the exposed deck with only small access openings to cargo compartments, closed bywatertight gasketed covers of steel or equivalent material・ has low permeability of loaded cargo compartments.
A Type A ship is to be assigned a freeboard following the requirements reported in the International Load Line
Convention 1966, as amended.
3.19.2 Type B ship
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 27.5)
All ships which do not come within the provisions regarding Type A ships stated in 3.19.1 are to be considered as
Type B ships.
A Type B ship is to be assigned a freeboard following the requirements reported in the International Load Line
Convention 1966, as amended.
3.19.3 Type B-60 ship
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 27.9)
A Type B-60 ship is any Type B ship of over 100 m in length which, according to applicable requirements of in theInternational Load Line Convention 1966, as amended, is assigned with a value of tabular freeboard which can be
reduced up to 60% of the difference between the B and A tabular values for the appropriate ship lengths.
3.19.4 Type B-100 ship
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 27.10)
A Type B-100 ship is any Type B ship of over 100 m in length which, according to applicable requirements of in
the International Load Line Convention 1966, as amended, is assigned with a value of tabular freeboard which can be
reduced up to 100% of the difference between the B and A tabular values for the appropriate ship lengths.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

3.20
Positions 1 and 2
3.20.1 Position 1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 13)
Position 1 includes:
・ exposed freeboard and raised quarter decks,
・ exposed superstructure decks situated forward of 0.25LLL from the perpendicular, at the forward side of the stem,to the waterline at 85% of the least moulded depth measured from the top of the keel.
3.20.2 Position 2
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 13)
Position 2 includes:
・ exposed superstructure decks situated aft of 0.25LLL from the perpendicular, at the forward side of the stem, tothe waterline at 85% of the least moulded depth measured from the top of the keel and located at least one
standard height of superstructure above the freeboard deck,・ exposed superstructure decks situated forward of 0.25LLL from the perpendicular, at the forward side of the stem,to the waterline at 85% of the least moulded depth measured from the top of the keel and located at least two
standard heights of superstructure above the freeboard deck.
3.21
Single Side Skin and Double Side Skin construction
3.21.1 Single side skin construction
A hold of single side skin construction is bounded by the side shell between the inner bottom plating or the hoppertank plating when fitted, and the deck plating or the topside tank plating when fitted.
3.21.2 Double side skin construction
A hold of double side skin construction is bounded by a double side skin, including hopper tank and topside tankwhen fitted.
3.22
Bilge
3.22.1 Bilge plating
The bilge plating is the curved plating between the bottom shell and side shell. It is to be taken as follows:・ within the cylindrical part of the ship (see Fig.4):
from the start of the curvature at the lower turn of bilge on the bottom to the end of the curvature at the upper
turn of the bilge,
・ outside the cylindrical part of the ship (see Fig.5):
From the start of the curvature at the lower turn of the bilge on the bottom to the lesser of:・ a point on the side shell located 0.2D above the baseline/local centreline elevation.
・ the end of the curvature at the upper turn of the bilge.
Fig. 4

Vertical extent of bilge plating within the cylindrical part of the hull－18－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 1 Section 4)

Fig. 5

4.

Vertical extent of bilge plating outside the cylindrical part of the hull

Reference co-ordinate system

4.1
4.1.1
The ship s geometry, motions, accelerations and loads are defined with respect to the following right-handco-ordinate system (see Fig. 6):
・ Origin: at the intersection among the longitudinal plane of symmetry of ship, the aft end of LCSR-B and thebaseline
・ X axis: longitudinal axis, positive forwards
・ Y axis: transverse axis, positive towards portside
・ Z axis: vertical axis, positive upwards.
Fig. 6

Reference co-ordinate system

4.1.2
Positive rotations are oriented in anti-clockwise direction about the X, Y and Z axes.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 1)

Chapter 2

GENERAL ARRANGEMENT DESIGN

Section 1
1.

SUBDIVISION ARRANGEMENT

Number and arrangement of transverse watertight bulkheads

1.1
Number of watertight bulkheads
1.1.1 General
All ships, in addition to complying with the requirements of 1.1.2, are to have at least the following transverse
watertight bulkheads:
・ one collision bulkhead・ one after peak bulkhead
・ two bulkheads forming the boundaries of the machinery space in ships with machinery amidships, and abulkhead forward of the machinery space in ships with machinery aft. In the case of ships with an electrical
propulsion plant, both the generator room and the engine room are to be enclosed by watertight bulkheads.
1.1.2 Additional bulkheads
For ships not required to comply with subdivision requirements, transverse bulkheads adequately spaced, and notless in number than indicated in Table 1, are to be fitted.
Table 1

Number of bulkheads

Number of bulkheads for

Numbers of bulkheads

ships with aft machinery(1)for other ships

90 £ LCSR-B < 1054

5

105 £ LCSR-B < 120

5

6120 £ LCSR-B < 14567

145 £ LCSR-B < 16578165 £ LCSR-B < 190

8

9Length (m)LCSR -B ³ 190

To be defined on a case by case basis(1) After peak bulkhead and aft machinery bulkhead are the same.

2.

Collision bulkhead

2.1
Arrangement of collision bulkhead
2.1.1
Ref. SOLAS Ch. II-1, Part B-2, Reg. 12
A collision bulkhead is to be fitted which is to be watertight up to the freeboard deck. This bulkhead is to belocated at a distance from the forward perpendicular FPLL of not less than 0.05LLL or 10 m, whichever is the less, and,except as may be permitted by the Society, not more than 0.08LLL or 0.05 LLL +3 m, whichever is the greater.
2.1.2
Ref. SOLAS Ch. II-1, Part B-2, Reg. 12
Where any part of the ship below the waterline extends forward of the forward perpendicular, e.g. a bulbous bow,the distances, in metres, stipulated in [2.1.1] are to be measured from a point either:・ at the mid-length of such extension, or・ at a distance 1.5% of the length LLL of the ship forward of the forward perpendicular, or・ at a distance 3 m forward of the forward perpendicular, whichever gives the smallest measurement.
2.1.3
Ref. SOLAS Ch. II-1, Part B-2, Reg. 12
The bulkhead may have steps or recesses provided they are within the limits prescribed in 2.1.1 or 2.1.2.
No door, manhole, ventilation duct or any other opening is to be fitted in this bulkhead.
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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 1)

3.

After peak, machinery space bulkheads and stern tubes

3.1
General3.1.1
An aft peak bulkhead, enclosing the stern tube and rudder trunk in a watertight compartment, is to be provided.
Where the shafting arrangements make enclosure of the stern tube in a watertight compartment impracticalalternative arrangements will be specially considered.
3.1.2
The aft peak bulkhead may be stepped below the bulkhead deck, provided that the degree of safety of the ship as
regards subdivision is not thereby diminished.
3.1.3
The aft peak bulkhead location on ships powered and/or controlled by equipment that does not require the fitting ofa stern tube and/or rudder trunk will also be subject to special consideration.
3.1.4
The aft peak bulkhead may terminate at the first deck above the summer load waterline, provided that this deck is
made watertight to the stern or to a watertight transom floor.
3.1.5 Sterntubes
Ref. SOLAS Ch. II-1, Part B-2, Reg. 12
Sterntubes are to be enclosed in a watertight space (or spaces) of moderate volume. Other measures to minimise
the danger of water penetrating into the ship in case of damage to sterntube arrangements may be taken at thediscretion of the Society.
4.

Number and arrangement of tank bulkheads

4.1
Bulkheads in compartments intended for the carriage of liquid cargoes
4.1.1
The number and location of transverse and longitudinal watertight bulkheads in compartments intended for the
carriage of liquid cargoes are to comply with the subdivision requirements to which the ship is subject.
5.

Arrangement of transverse watertight bulkheads

5.1
General
5.1.1
Where it is not practicable to arrange a watertight bulkhead in one plane, a stepped bulkhead may be fitted. In thiscase, the part of the deck which forms the step is to be watertight and equivalent in strength to the bulkhead.
6.

Openings in watertight bulkheads

6.1
General
6.1.1
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9 and IMO Res. A.684(17) - Part B
The number of openings in watertight subdivisions is to be kept to a minimum compatible with the design andproper working of the ship. Where penetrations of watertight bulkheads and internal decks are necessary for access,piping, ventilation, electrical cables, etc., arrangements are to be made to maintain the watertight integrity. The
Society may permit relaxation in the watertightness of openings above the freeboard deck, provided that it isdemonstrated that any progressive flooding can be easily controlled and that the safety of the ship is not impaired.
6.1.2
No door, manhole ventilation duct or any other opening is permitted in the collision bulkhead below thesubdivision deck.
6.1.3
Lead or other heat sensitive materials may not be used in systems which penetrate watertight subdivisionbulkheads, where deterioration of such systems in the event of fire would impair the watertight integrity of thebulkheads.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 1)

6.1.4
Valves not forming part of a piping system are not permitted in watertight subdivision bulkheads.
6.1.5
The requirements relevant to the degree of tightness, as well as the operating systems, for doors or other closing
appliances complying with the provisions in 6.2 and 6.3 are specified in Table 2.
6.2
Openings in the watertight bulkheads below the freeboard deck
6.2.1 Openings used while at sea
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9
Doors provided to ensure the watertight integrity of internal openings which are used while at sea are to be sliding
watertight doors capable of being remotely closed from the bridge and are also to be operable locally from each sideof the bulkhead. Indicators are to be provided at the control position showing whether the doors are open or closed,
and an audible alarm is to be provided at the door closure. The power, control and indicators are to be operable in theevent of main power failure. Particular attention is to be paid to minimise the effect of control system failure. Eachpower-operated sliding watertight door is to be provided with an individual hand-operated mechanism. The
possibility of opening and closing the door by hand at the door itself from both sides is to be assured.
6.2.2 Openings normally closed at sea
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9
Access doors and access hatch covers normally closed at sea, intended to ensure the watertight integrity of internal
openings, are to be provided with means of indication locally and on the bridge showing whether these doors or hatch
covers are open or closed. A notice is to be affixed to each such door or hatch cover to the effect that it is not to beleft open. The use of such doors and hatch covers is to be authorised by the officer of the watch.
6.2.3 Doors or ramps in large cargo spaces
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9
Watertight doors or ramps of satisfactory construction may be fitted to internally subdivide large cargo spaces,
provided that the Society is satisfied that such doors or ramps are essential. These doors or ramps may be hinged,
rolling or sliding doors or ramps, but are not to be remotely controlled.
Such doors are to be closed before the voyage commences and are to be kept closed during navigation. Should anyof the doors or ramps be accessible during the voyage, they are to be fitted with a device which prevents unauthorised
opening.
The word satisfactory means that scantlings and sealing requirements for such doors or ramps are to be sufficient
to withstand the maximum head of the water at the flooded waterline.
6.2.4 Openings permanently kept closed at sea
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9
Other closing appliances which are kept permanently closed at sea to ensure the watertight integrity of internal
openings are to be provided with a notice which is to be affixed to each such closing appliance to the effect that it is
to be kept closed. Manholes fitted with closely bolted covers need not be so marked.
6.3
Openings in the bulkheads above the freeboard deck
6.3.1 General
The openings in flooding boundaries located below the waterline at the equilibrium of the final stage of flooding
are to be watertight. The openings immersed within the range of the positive righting lever curve are only to be
weathertight.
6.3.2 Doors used while at sea
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9
The doors used while at sea are to be sliding doors capable of being remotely closed from the bridge and are also to
be operable locally from each side of the bulkhead. Indicators are to be provided at the control position showing
whether the doors are open or closed, and an audible alarm is to be provided at the door closure. The power, control
and indicators are to be operable in the event of main power failure. Particular attention is to be paid to minimise theeffect of control system failure. Each power-operated sliding watertight door is to be provided with an individual
hand-operated mechanism. It should be possible to open and close the door by hand at the door itself from both sides.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 1)

6.3.3 Doors normally closed at sea
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9
The doors normally closed at sea are to be provided with means of indication locally and on the bridge showing
whether these doors are open or closed. A notice is to be affixed to each door to the effect that it is not to be left open.
6.3.4 Openings kept permanently closed at sea
Ref. SOLAS Ch. II-1, Part B-1, Reg. 25-9
The doors kept closed at sea are to be hinged doors. Such doors and the other closing appliances which are kept
closed at sea are to be provided with a notice affixed to each closing appliance to the effect that it is to be kept closed.
Manholes fitted with closely bolted covers need not be so marked.
Table 2

Doors

Sliding type
Remoteoperation

Indicator on

indication on

the bridge

the bridge
Open atBelow theWatertightfreeboard
deck

sea

Remain/watertight(1)

Above thefreeboarddeck

indication on
the bridgeon thebridgeLocal
operation between
deck
only
spaces)X(4)(5)

X(4)(5)

X

Normally
closed(2)X

RemainX
X(4)(5)closed(2)(1)

operation

type

X(4)(5)closed(2)Weathertight

Indicator(cargoRemoteX(3)X

closed(2)

sea

only

Rolling

X

Normally

Open atLocal
operation

Hinged type

Watertight doors are required when they are located below the waterline at the equilibrium of the final stage of flooding;otherwise a weathertight door is accepted.

(2)

Notice to be affixed on both sides of the door: to be kept closed at sea .

(3)Type A ships of 150 m and upwards, and Type B ships with a reduced freeboard may have a hinged watertight door
between the engine room and the steering gear space, provided that the sill of this door is above the summer loadwaterline.

(4)

The door is to be closed before the voyage commences.

(5)

If the door is accessible during the voyage, a device which prevents unauthorised opening is to be fitted.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 2)

Section 2
1.

COMPARTMENT ARRANGEMENT

Definitions

1.1
Cofferdam
1.1.1
A cofferdam means an empty space arranged so that compartments on each side have no common boundary; acofferdam may be located vertically or horizontally. As a rule, a cofferdam is to be properly ventilated and of
sufficient size to allow proper inspection, maintenance and safe evacuation.
1.2
Machinery spaces of category A
1.2.1
Ref. SOLAS Ch. II-2, Part A, Reg. 3.31
Machinery spaces of category A are those spaces or trunks to such spaces which contain:
・ internal combustion machinery used for main propulsion; or・ internal combustion machinery used for purposes other than propulsion where such machinery has in theaggregate a total power output of not less than 375 kW; or・ any oil fired boiler or fuel oil unit.
2.

Cofferdams

2.1
Cofferdam arrangement
2.1.1
Cofferdams are to be provided between compartments intended for liquid hydrocarbons (fuel oil, lubricating oil)and those intended for fresh water (drinking water, water for propelling machinery and boilers) as well as tanks
intended for the carriage of liquid foam for fire extinguishing.
2.1.2
Cofferdams separating fuel oil tanks from lubricating oil tanks and the latter from those intended for the carriage ofliquid foam for fire extinguishing or fresh water or boiler feed water may be waived when deemed impracticable or
unreasonable by the Society in relation to the characteristics and dimensions of the spaces containing such tanks,
provided that:・ the thickness of common boundary plates of adjacent tanks is increased, with respect to the thickness obtained
according to Ch 6, Sec 1, by 2 mm in the case of tanks carrying fresh water or boiler feed water, and by 1 mm inall other cases
・ the sum of the throats of the weld fillets at the edges of these plates is not less than the thickness of the plates
themselves
・ the structural test is carried out with a head increased by 1 m with respect to Ch 11, Sec 3.
2.1.3(Void)
2.1.4
Cofferdams are only required between fuel oil double bottoms and tanks immediately above where the inner
bottom plating is subjected to the head of fuel oil contained therein, as in the case of a double bottom with its top
raised at the sides.
Where a corner to corner situation occurs, tanks are not considered to be adjacent.
Adjacent tanks not separated by cofferdams are to have adequate dimensions to ensure easy inspection.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 2)

3.

Double bottoms

3.1
General
3.1.1
Ref. SOLAS Ch. II-1, Part B, Reg. 12-1
A double bottom is to be fitted extending from the collision bulkhead to the after peak bulkhead, as far as this ispracticable and compatible with the design and proper working of the ship.
3.1.2
Ref. SOLAS Ch. II-1, Part B, Reg. 12-1
Where a double bottom is required to be fitted, its depth is to satisfy the provisions of Ch 3, Sec 6, 6 and the inner
bottom is to be continued out to the ship side in such a manner as to protect the bottom to the turn of the bilge.
3.1.3
Ref. SOLAS Ch. II-1, Part B, Reg. 12-1
Small wells constructed in the double bottom, in connection with the drainage arrangements of holds, are not toextend in depth more than necessary. A well extending to the outer bottom, may, however, be permitted at the afterend of the shaft tunnel of the ship. Other wells may be permitted by the Society if it is satisfied that the arrangements
give protection equivalent to that afforded by a double bottom complying with 3.1.
3.1.4
Ref. SOLAS Ch. II-1, Part B, Reg. 12-1
A double bottom need not be fitted in way of watertight compartments used exclusively for the carriage of liquids,
provided the safety of the ship in the event of bottom damage is not, in the opinion of the Society, thereby impaired.
4.

Compartment forward of the collision bulkhead

4.1
General
4.1.1
The fore peak and other compartments located forward of the collision bulkhead may not be arranged for the
carriage of fuel oil or other flammable products.
5.

Minimum bow height

5.1
General
5.1.1
Ref. ILLC, as amended (Resolution MSC.223(82) Reg. 39(1))
The bow height Fb, defined as the vertical distance at the forward perpendicular between the waterline
corresponding to the assigned summer freeboard and the designed trim and the top of the exposed deck at side, is tobe not less than:Fb = (6075(LLL/100) 1875(LLL/100)2 + 200(LLL/100)3)(2.08 + 0.609CB 1.603Cwf 0.0129(LLL/T1))
where:
Fb : Calculated minimum bow height, in mm
T1 : Draught at 85% of the least moulded depth, in m
Cwf : Waterplane area coefficient forward of LLL/2:
Awf
Cwf =
L LL
B
2
Awf : Waterplane area forward of LLL/2 at draught T1, in m2.
For ships to which timber freeboards are assigned, the summer freeboard (and not the timber summer freeboard) is
to be assumed when applying the formula above.
5.1.2
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 39.(2))
Where the bow height required in paragraph 5.1.1 is obtained by sheer, the sheer is to extend for at least 15% of
the length of the ship measured from the forward perpendicular. Where it is obtained by fitting a superstructure, such－25－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 2)

superstructure is to extend from the stem to a point at least 0.07LLL abaft the forward perpendicular, and is to be
enclosed as defined Ch 9, Sec 4.
5.1.3
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 39(3))
Ships which, to suit exceptional operational requirements, cannot meet the requirements in 5.1.1 and 5.1.2 will beconsidered by the Society on a case by case basis.
5.1.4
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 39(4, a))
The sheer of the forecastle deck may be taken into account, even if the length of the forecastle is less than 0.15LLL,
but greater than 0.07LLL, provided that the forecastle height is not less than one half of standard height ofsuperstructure between 0.07LLL and the forward perpendicular.
5.1.5
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 39(4, b))
Where the forecastle height is less than one half of the standard height of superstructure, the credited bow height
may be determined as follows:a) Where the freeboard deck has sheer extending from abaft 0.15LLL, by a parabolic curve having its origin at 0.15
LLL abaft the forward perpendicular at a height equal to the midship depth of the ship, extended through the pointof intersection of forecastle bulkhead and deck, and up to a point at the forward perpendicular not higher thanthe level of the forecastle deck (as illustrated in Fig. 1). However, if the value of the height denoted ht in Fig. 1
is smaller than the value of the height denoted hb then ht may be replaced by hb in the available bow height,
where:
2

Fig. 1Credited bow height where the freeboard deck has sheer extending from abaft 0.15LLL

hf

hf

ola
arab
p
rd
nda
Sta

hb

Xb

Zb

Credited bow
heightb)

æ 0.15LLL ö
ht = Z b çç
- Zt
è xb ø
Zb : As defined in Fig. 1
Zt : As defined in Fig. 1
hf : Half standard height of superstructure
Where the freeboard deck has sheer extending for less than 0.15LLL or has no sheer, by a line from the forecastle
deck at side at 0.07LLL extended parallel to the base line to the forward perpendicular (as illustrated in Fig. 2).

ht
Zt

0.07LLL
0.07L

0.15L
0.15LLL

FP－26－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 2)

Fig. 2Credited bow height where the freeboard deck has sheer extending for less than 0.15LLL

hf

0.15L
0.15LLL

Credited bow
heighthf

0.07LLL
0.07L

FP
6.

Shaft tunnels

6.1
General6.1.1
Shaft tunnels are to be watertight.
7.

Watertight ventilators and trunks

7.1
General
7.1.1
Ref. SOLAS Ch. II-1, Part B, Reg. 19.1
Watertight ventilators and trunks are to be carried at least up to the freeboard deck.
8.

Fuel oil tanks

8.1
General
8.1.1
Ref. SOLAS Ch. II-2, Part B, Reg. 4.2
The arrangements for the storage, distribution and utilisation of the fuel oil are to be such as to ensure the safety ofthe ship and persons on board.
8.1.2
Ref. SOLAS Ch. II-2, Part B, Reg. 4.2
As far as practicable, fuel oil tanks are to be part of the ship s structure and are to be located outside machinery
spaces of category A.
Where fuel oil tanks, other than double bottom tanks, are necessarily located adjacent to or within machinery
spaces of category A, at least one of their vertical sides is to be contiguous to the machinery space boundaries, they
are preferably to have a common boundary with the double bottom tanks and the area of the tank boundary common
with the machinery spaces is to be kept to a minimum.
Where such tanks are situated within the boundaries of machinery spaces of category A, they may not contain fueloil having a flashpoint of less than 60 C.
8.1.3
Ref. SOLAS Ch. II-2, Part B, Reg. 4.2
Fuel oil tanks may not be located where spillage or leakage therefrom can constitute a hazard by falling on heatedsurfaces.
Precautions are to be taken to prevent any oil that may escape under pressure from any pump, filter or heater fromcoming into contact with heated surfaces.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 2)

Fuel oil tanks in boiler spaces may not be located immediately above the boilers or in areas subjected to hightemperatures, unless special arrangements are provided in agreement with the Society.
8.1.4
Where a compartment intended for goods or coal is situated in proximity of a heated liquid container, suitable
thermal insulation is to be provided.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

Section 3
1.

ACCESS ARRANGEMENT

General

1.0
Application
1.0.1
This section applies to ships of 20,000 gross tonnage and over.
1.1
Means of access to cargo and other spaces
1.1.1
Ref. SOLAS Reg.II-1/3-6 .2.1 (Resolution MSC.151(78))
Each space is to be provided with means of access to enable, throughout the life of a ship, overall and close-up
inspections and thickness measurements of the ship s structures. Such means of access are to comply with 1.3 and 2.
1.1.2
Ref. SOLAS Reg.II-1/3-6 .2.2 (Resolution MSC.151(78))
Where a permanent means of access may be susceptible to damage during normal cargo loading and unloading
operations or where it is impracticable to fit permanent means of access, the Society may allow, in lieu thereof, theprovision of movable or portable means of access, as specified in 2, provided that the means of attaching, rigging,suspending or supporting the portable means of access forms a permanent part of the ship s structure. All portableequipment are to be capable of being readily erected or deployed by ship s personnel.
1.1.3
Ref. SOLAS Reg.II-1/3-6 .2.3 (Resolution MSC.151(78))
The construction and materials of all means of access and their attachment to the ship s structure are to be to thesatisfaction of the Society.
1.2
Safe access to cargo holds, ballast tanks and other spaces
1.2.1
Ref. SOLAS Reg.II-1/3-6 .3.1 (Resolution MSC.151(78)) and IACS UI SC191
Safe access to cargo holds, cofferdams, ballast tanks and other spaces in the cargo area are to be direct from theopen deck and such as to ensure their complete inspection. Safe access to double bottom spaces or to forward ballast
tanks may be from a pump-room, deep cofferdam, pipe tunnel, cargo hold, double hull space or similar compartment
not intended for the carriage of oil or hazardous cargoes.
Access to a double side skin space may be either from a topside tank or double bottom tank or from both.
1.2.2
Ref. SOLAS Reg.II-1/3-6 .3.2 (Resolution MSC.151(78))
Tanks, and subdivisions of tanks, having a length of 35 m or more, are to be fitted with at least two accesshatchways and ladders, as far apart as practicable.
Tanks less than 35 m in length are to be served by at least one access hatchway and ladder.
When a tank is subdivided by one or more swash bulkheads or similar obstructions which do not allow readymeans of access to the other parts of the tank, at least two hatchways and ladders are to be fitted.
1.2.3
Ref. SOLAS Reg.II-1/3-6 .3.3 (Resolution MSC.151(78))
Each cargo hold is to be provided with at least two means of access as far apart as practicable. In general, theseaccesses are to be arranged diagonally, for example one access near the forward bulkhead on the port side, the otherone near the aft bulkhead on the starboard side.
1.3
General technical specifications
1.3.1
Ref. SOLAS Reg.II-1/3-6 .5.1 (Resolution MSC.151(78)) and IACS UI SC191
For access through horizontal openings, hatches or manholes, the dimensions are to be sufficient to allow a person
wearing a self-contained air-breathing apparatus and protective equipment to ascend or descend any ladder without－29－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

obstruction and also provide a clear opening to facilitate the hoisting of an injured person from the bottom of thespace. The minimum clear opening is to be not less than 600 mm 600 mm, with corner radii up to 100 mm
maximum.
In such a case where as a consequence of structural analysis the stress is to be reduced around the opening, it isconsidered appropriate to take measures to increase the clear opening, e.g. 600 800 with 300 mm radii, in which aclear opening of 600 600 mm with corner radii up to 100 mm maximum fits.
When access to a cargo hold is arranged through the cargo hatch, the top of the ladder is to be placed as close as
possible to the hatch coaming. Access hatch coamings having a height greater than 900 mm are also to have steps on
the outside in conjunction with the ladder.
1.3.2
Ref. SOLAS Reg.II-1/3-6 .5.2 (Resolution MSC.151(78)) and IACS UI SC191
For access through vertical openings, or manholes, in swash bulkheads, floors, girders and web frames providing
passage through the length and breadth of the space, the minimum opening is to be not less than 600 mm 800 mm
with corner radii of 300 mm at a height of not more than 600 mm from the bottom shell plating unless gratings orother foot holds are provided.
Subject to verification of easy evacuation of injured person on a stretcher the vertical opening 850 mm 620 mmwith wider upper half than 600 mm, while the lower half may be less than 600 mm with the overall height not lessthan 850 mm is considered acceptable alternative to the opening of 600 mm 800 mm with corner radii of 300 mm(see Fig. 1).
Fig. 1

2.

Alternative vertical opening

Technical provisions for means of access

2.1
Definitions
Ref. IMO Technical Provisions, 2 (Resolution MSC.158(78))
2.1.1 Rung
Rung means the step of vertical ladder or step on the vertical surface.
2.1.2 Tread
Tread means the step of inclined ladder, or step for the vertical access opening.
2.1.3 Flight of a ladder
Flight of an inclined ladder means the actual stringer length of an inclined ladder.
For vertical ladders, it is the distance between the platforms.
2.1.4 Stringer
Stringer means:
1) the frame of a ladder; or2) the stiffened horizontal plating structure fitted on side shell, transverse bulkheads and/or longitudinal bulkheads
in the space. For the purpose of ballast tanks of less than 5 m width forming double side spaces, the horizontal
plating structure is credited as a stringer and a longitudinal permanent means of access, if it provides acontinuous passage of 600 mm or more in width past frames or stiffeners on the side shell or longitudinalbulkhead. Openings in stringer plating utilized as permanent means of access are to be arranged with guard rails
or grid covers to provide safe passage on the stringer or safe access to each transverse web.
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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

2.1.5 Vertical ladder
Vertical ladder means a ladder of which the inclined angle is 70º and over up to 90º. Vertical ladder is to be notskewed by more than 2º.
2.1.6 Overhead obstructions
Overhead obstructions mean the deck or stringer structure including stiffeners above the means of access.
2.1.7 Distance below deck head
Distance below deck head means the distance below the plating.
2.1.8 Cross deck
Cross deck means the transverse area of main deck which is located inboard and between hatch coamings.
2.2
Permanent means of access
2.2.1
Ref. IMO Technical Provisions, 3.1 & 3.2 (Resolution MSC.158(78))
Structural members, except those in double bottom spaces, are to be provided with a permanent means of access tothe extent as specified in 2.7 to 2.13.
Permanent means of access are, as far as possible, to be integral to the structure of the ships, thus ensuring that they
are robust and at the same time contributing to the overall strength of the structure, of the ship.
2.2.2
Ref. IMO Technical Provisions, 3.3 (Resolution MSC.158(78)) and IACS UI SC191
Elevated passageways forming sections of a permanent means of access, where fitted, are to have a minimum clear
width of 600 mm, except for going around vertical webs where the minimum clear width may be reduced to 450 mm,
and to have guard rails over the open side of their entire length. For stand alone passageways guard rails are to be
fitted on both sides of these structures.
Sloping structure providing part of the access and that are sloped by 5 or more degrees from horizontal plane whena ship is in upright position at even-keel, is to be of a non-skid construction.
Guard rails are to be 1000 mm in height and consist of a rail and intermediate bar 500 mm in height and of
substantial construction. Stanchions are to be not more than 3 m apart.
2.2.3
Ref. IMO Technical Provisions, 3.4 (Resolution MSC.158(78))
Access to permanent means of access and vertical openings from the ship s bottom are to be provided by means ofeasily accessible passageways, ladders or treads. Treads are to be provided with lateral support for the foot. Where
the rungs of ladders are fitted against a vertical surface, the distance from the centre of the rungs to the surface is to
be at least 150 mm. Where vertical manholes are fitted higher than 600 mm above the walking level, access is to be
facilitated by means of treads and hand grips with platform landings on both sides.
2.3
Construction of ladders
2.3.1 General
Ref. IMO Technical Provisions, 3.5 (Resolution MSC.158(78))
Permanent inclined ladders are to be inclined at an angle of less than 70º. There are to have no obstructions within
750 mm of the face of the inclined ladder, except that in way of an opening this clearance may be reduced to 600 mm.
Resting platforms of adequate dimensions are normally to be provided at a maximum of 6 m vertical height. Ladders
and handrails are to be constructed of steel or equivalent material of adequate strength and stiffness and securely
attached to the tank structure by stays. The method of support and length of stay is to be such that vibration is
reduced to a practical minimum. In cargo holds, ladders are to be designed and arranged so that cargo handlingdifficulties are not increased and the risk of damage from cargo handling gear is minimized.
2.3.2 Inclined ladders
Ref. IMO Technical Provisions, 3.6 (Resolution MSC.158(78))
The width of inclined ladders between stringers is to be not less than 400 mm. The treads are to be equally spaced
at a distance apart, measured vertically, of between 200 mm and 300 mm. When steel is used, the treads are to beformed of two square bars of not less than 22 mm by 22 mm in section, fitted to form a horizontal step with the edges
pointing upward. The treads are to be carried through the side stringers and attached thereto by double continuous
welding. All inclined ladders are to be provided with handrails of substantial construction on both sides, fitted at aconvenient distance above the treads.
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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

2.3.3 Vertical or spiral ladders
Ref. IMO Technical Provisions, 3.7 (Resolution MSC.158(78))
For vertical ladders or spiral ladders, the width and construction are to be in accordance with international or
national standards.
2.4
Access through openings
2.4.1 Access through horizontal openings, hatches or manholes
Ref. IMO Technical Provisions, 3.10 (Resolution MSC.158(78))
For access through horizontal openings, hatches or manholes, the minimum clear opening is to be not less than 600
mm 600 mm. When access to a cargo hold is arranged through the cargo hatch, the top of the ladder is to be placed
as close as possible to the hatch coaming.
Access hatch coamings having a height greater than 900 mm are also to have steps on the outside in conjunction
with the ladder.
2.4.2 Access through vertical openings, or manholes
Ref. IMO Technical Provisions, 3.11 (Resolution MSC.158(78))
For access through vertical openings, or manholes, in swash bulkheads, floors, girders and web frames providing
passage through the length and breadth of the space, the minimum opening is to be not less than 600 mm 800 mm ata height of not more than 600 mm from the passage unless gratings or other foot holds are provided.
2.5
Access ladders to cargo holds and other spaces
2.5.1 General
Ref. IMO Technical Provisions, 3.13.1 & 3.13.2 (Resolution MSC.158(78))
Access ladders to cargo holds and other spaces are to be:a) where the vertical distance between the upper surface of adjacent decks or between deck and the bottom of the
cargo space is not more than 6 m, either a vertical ladder or an inclined ladder.
b) where the vertical distance between the upper surface of adjacent decks or between deck and the bottom of the
cargo space is more than 6 m, an inclined ladder or series of inclined ladders at one end of the cargo hold, except
the uppermost 2.5 m of a cargo space measured clear of overhead obstructions and the lowest 6 m may havevertical ladders, provided that the vertical extent of the inclined ladder or ladders connecting the vertical ladders
is not less than 2.5 m.
2.5.2
Ref. IMO Technical Provisions, 3.13.2 (Resolution MSC.158(78))
The second means of access at the other end of the cargo hold may be formed of a series of staggered verticalladders, which have to comprise one or more ladder linking platforms spaced not more than 6 m apart vertically anddisplaced to one side of the ladder. Adjacent sections of ladder are to be laterally offset from each other by at least thewidth of the ladder. The uppermost, entrance section, of the ladder directly exposed to a cargo hold is to be verticalfor a distance of 2.5 m measured clear of overhead obstructions and connected to a ladder-linking platform.
2.5.3
Ref. IMO Technical Provisions, 3.13.3 (Resolution MSC.158(78))
A vertical ladder may be used as a means of access to topside tanks, where the vertical distance is 6 m or lessbetween the deck and the longitudinal means of access in the tank or the stringer or the bottom of the space
immediately below the entrance. The uppermost, entrance section from deck, of the vertical ladder of the tank is to bevertical for a distance of 2.5 m measured clear of the overhead obstructions and comprises a ladder linking platform
unless landing on the longitudinal means of access, the stringer or the bottom within the vertical distance, it should be
displaced to one side of a vertical ladder.
2.5.4
Ref. IMO Technical Provisions, 3.13.4 (Resolution MSC.158(78))
Unless allowed in 2.5.3, an inclined ladder or combination of ladders are to be used for access to a tank or a space
where the vertical distance is greater than 6 m between the deck and a stringer immediately below the entrance,
between stringers, or between the deck or a stringer and the bottom of the space immediately below the entrance.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

2.5.5
Ref. IMO Technical Provisions, 3.13.5 (Resolution MSC.158(78))
In case of 2.5.4, the uppermost, entrance section from deck, of the ladder is to be vertical for a distance of 2.5 m
clear of the overhead obstructions and connected to a landing platform and continued with an inclined ladder. The
flights of inclined ladders are to be not more than 9 m in actual length and the vertical height is normally to be notmore than 6 m. The lowermost section of the ladders may be vertical for a vertical distance of not less than 2.5 m.
2.5.6
Ref. IMO Technical Provisions, 3.13.6 (Resolution MSC.158(78))
In double side skin spaces of less than 2.5 m width, the access to the space may be by means of vertical ladders thatcomprises one or more ladder linking platforms spaced not more than 6 m apart vertically and displace to one side ofthe ladder.
Adjacent sections of ladder are to be laterally offset from each other by at least the width of the ladder.
2.5.7
Ref. IMO Technical Provisions, 3.13.7 (Resolution MSC.158(78))
A spiral ladder is considered acceptable as an alternative for inclined ladders. In this regard, the uppermost 2.5 m
can continue to be comprised of the spiral ladder and need not change over to vertical ladders.
2.6
Access ladders to tanks
2.6.1
Ref. IMO Technical Provisions, 3.14 (Resolution MSC.158(78))
The uppermost, entrance section from deck, of the vertical ladder providing access to a tank should be vertical fora distance of 2.5 m measured clear of the overhead obstructions and comprises a ladder linking platform. It should be
displaced to one side of a vertical ladder. The vertical ladder can be between 1.6 m and 3 m below deck structure if it
lands on a longitudinal or athwartship permanent means of access fitted within that range.
2.7
Access to underdeck structure of cargo holds
2.7.1
Ref. IMO Technical Provisions, Table 2, 1.1 (Resolution MSC.158(78))
Permanent means of access are to be fitted to provide access to the overhead structure at both sides of the crossdeck and in the vicinity of the centerline.
Each means of access is to be accessible from the cargo hold access or directly from the main deck and installed at
a minimum of 1.6 m to a maximum of 3 m below the deck.
2.7.2
Ref. IMO Technical Provisions, Table 2, 1.2 (Resolution MSC.158(78))
An athwartship permanent means of access fitted on the transverse bulkhead at a minimum 1.6 m to a maximum 3
m below the cross-deck head is accepted as equivalent to 2.7.1.
2.7.3
Ref. IMO Technical Provisions, Table 2, 1.3 (Resolution MSC.158(78))
Access to the permanent means of access to overhead structure of the cross deck may also be via the upper stool.
2.7.4
Ref. IMO Technical Provisions, Table 2, 1.4 (Resolution MSC.158(78)) and IACS UI SC191
Ships having transverse bulkheads with full upper stools, i.e. stools with a full extension between top side tanks
and between hatch end beams, with access from the main deck which allows monitoring of all framing and plates
from inside, do not require permanent means of access of the cross deck.
2.7.5
Ref. IMO Technical Provisions, Table 2, 1.5 (Resolution MSC.158(78))
Alternatively, movable means of access may be utilized for access to the overhead structure of cross deck if its
vertical distance is 17 m or less above the tank top.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

2.8
Access to double side skin tanks of double side skin construction
2.8.1
Ref. IMO Technical Provisions, Table 2, 2.8 & Table 1, 2.1 (Resolution MSC.158(78))
For double side spaces above the upper knuckle point of the bilge hopper sections, permanent means of access areto be provided in accordance with the following requirements:a) where the vertical distance between horizontal uppermost stringer and deck head is 6 m or more, one continuous
longitudinal permanent means of access is to be provided for the full length of the tank with a means to allow
passing through transverse webs installed at a minimum of 1.6 m to a maximum of 3 m below the deck headwith a vertical access ladder at each end of the tank;b) continuous longitudinal permanent means of access, which are integrated in the structure, at a vertical distance
not exceeding 6 m apart; andc) plated stringers are to be, as far as possible, in alignment with horizontal girders of transverse bulkheads.
2.9
Access to vertical structures of cargo holds of single side skin construction
2.9.1
Ref. IMO Technical Provisions, Table 2, 1.6 (Resolution MSC.158(78))
Permanent means of vertical access are to be provided in all cargo holds and built into the structure to allow for aninspection of a minimum of 25 % of the total number of hold frames port and starboard equally distributed
throughout the hold including at each end in way of transverse bulkheads. But in no circumstance is this arrangement
to be less than 3 permanent means of vertical access fitted to each side (fore and aft ends of hold and mid-span).
Permanent means of vertical access fitted between two adjacent hold frames is counted for an access for theinspection of both hold frames. A means of portable access may be used to gain access over the sloping plating oflower hopper ballast tanks.
2.9.2
Ref. IMO Technical Provisions, Table 2, 1.7 (Resolution MSC.158(78))
In addition, portable or movable means of access are to be utilized for access to the remaining hold frames up to
their upper brackets and transverse bulkheads.
2.9.3
Ref. IMO Technical Provisions, Table 2, 1.8 (Resolution MSC.158(78))
Portable or movable means of access may be utilized for access to hold frames up to their upper bracket in place ofthe permanent means required in 2.9.1. These means of access are to be carried on board the ship and readily
available for use.
2.9.4
Ref. IMO Technical Provisions, Table 2, 1.9 (Resolution MSC.158(78))
The width of vertical ladders for access to hold frames is to be at least 300 mm, measured between stringers.
2.9.5
Ref. IMO Technical Provisions, Table 2, 1.10 (Resolution MSC.158(78))
A single vertical ladder over 6 m in length is acceptable for the inspection of the hold side frames in a single skinconstruction.
2.10
Access to vertical structures of cargo holds of double side skin construction
2.10.1
Ref. IMO Technical Provisions, Table 2, 1.11 (Resolution MSC.158(78))
For double side skin construction no vertical ladders for the inspection of the cargo hold surfaces are required.
Inspection of this structure should be provided from within the double hull space.
2.11
Access to top side ballast tanks
2.11.1
Ref. IMO Technical Provisions, Table 2, 2.1 (Resolution MSC.158(78))
For each topside tank of which the height is 6 m and over, one longitudinal continuous permanent means of accessis to be provided along the side shell webs and installed at a minimum of 1.6 m to a maximum of 3 m below deckwith a vertical access ladder in the vicinity of each access to that tank.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

2.11.2
Ref. IMO Technical Provisions, Table 2, 2.2 (Resolution MSC.158(78))
If no access holes are provided through the transverse webs within 600 mm of the tank base and the web framerings have a web height greater than 1 m in way of side shell and sloping plating, then step rungs/grab rails are to beprovided to allow safe access over each transverse web frame ring.
2.11.3
Ref. IMO Technical Provisions, Table 2, 2.3 (Resolution MSC.158(78))
Three permanent means of access, fitted at the end bay and middle bay of each tank, are to be provided spanningfrom tank base up to the intersection of the sloping plate with the hatch side girder. The existing longitudinal
structure, if fitted on the sloping plate in the space may be used as part of this means of access.
2.11.4
Ref. IMO Technical Provisions, Table 2, 2.4 (Resolution MSC.158(78))
For topside tanks of which the height is less than 6 m, alternative or a portable means may be utilized in lieu of thepermanent means of access.
2.12
Access to bilge hopper ballast tanks
2.12.1
Ref. IMO Technical Provisions, Table 2, 2.5 (Resolution MSC.158(78)) and IACS UI SC191
For each bilge hopper tank of which the height is 6 m and over, one longitudinal continuous permanent means ofaccess is to be provided along the side shell webs and installed at a minimum of 1.2 m below the top of the clear
opening of the web ring with a vertical access ladder in the vicinity of each access to the tank.
An access ladder between the longitudinal continuous permanent means of access and the bottom of the space is tobe provided at each end of the tank.
Alternatively, the longitudinal continuous permanent means of access can be located through the upper web plating
above the clear opening of the web ring, at a minimum of 1.6 m below the deck head, when this arrangement
facilitates more suitable inspection of identified structurally critical areas. An enlarged longitudinal frame, of at least
600 mm clear width can be used for the purpose of the walkway.
For double side skin bulk carriers the longitudinal continuous permanent means of access may be installed within 6
m from the knuckle point of the bilge, if used in combination with alternative methods to gain access to the knuckle
point.
2.12.2
Ref. IMO Technical Provisions, Table 2, 2.6 (to Resolution MSC.158(78))
If no access holes are provided through the transverse ring webs within 600 mm of the tank base and the web framerings have a web height greater than 1 m in way of side shell and sloping plating, then step rungs/grab rails are to beprovided to allow safe access over each transverse web frame ring.
2.12.3
Ref. IMO Technical Provisions, Table 2, 2.7 (Resolution MSC.158(78))
For bilge hopper tanks of which the height is less than 6 m, alternative or a portable means may be utilized in lieu
of the permanent means of access. Such means of access are to be demonstrated that they can be deployed and madereadily available in the areas where needed.
2.13
Access to fore peak tanks
2.13.1
Ref. IMO Technical Provisions, Table 2, 2.9 (Resolution MSC.158(78))
For fore peak tanks with a depth of 6 m or more at the centreline of the collision bulkhead, a suitable means ofaccess is to be provided for access to critical areas such as the underdeck structure, stringers, collision bulkhead andside shell structure.
2.13.2
Ref. IMO Technical Provisions, Table 2, 2.9.1 (Resolution MSC.158(78))
Stringers of less than 6 m in vertical distance from the deck head or a stringer immediately above are considered toprovide suitable access in combination with portable means of access.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 2 Section 3)

2.13.3
Ref. IMO Technical Provisions, Tab 2, 2.9.2 (Resolution MSC.158(78))
In case the vertical distance between the deck head and stringers, stringers or the lowest stringer and the tankbottom is 6 m or more, alternative means of access are to be provided.
3.

Shaft tunnels

3.1
General
3.1.1
Tunnels are to be large enough to ensure easy access to shafting.
3.1.2
Access to the tunnel is to be provided by a watertight door fitted on the aft bulkhead of the engine room incompliance with Ch 2, Sec 1, 6, and an escape trunk which can also act as watertight ventilator is to be fitted up to
the subdivision deck, for tunnels greater than 7 m in length.
4.

Access to steering gear compartment

4.1
General
4.1.1
The steering gear compartment is to be readily accessible and, as far as practicable, separated from machinery
spaces.
4.1.2
Suitable arrangements to ensure working access to steering gear machinery and controls are to be provided.
These arrangements are to include handrails and gratings or other non-slip surfaces to ensure suitable working
conditions in the event of hydraulic fluid leakage.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

Chapter 3

STRUCTURAL DESIGN PRINCIPLES
Section 1

1.

MATERIAL

General1.1Standard of material
1.1.1
The requirements in this Section are intended for ships of welded construction using steels having characteristics
complying with the requirements of Part K.
1.1.2
Materials with different characteristics may be accepted, provided their specification (manufacture, chemicalcomposition, mechanical properties, welding, etc.) is submitted to the Society for approval.
1.2
Testing of materials
1.2.1
Materials are to be tested in compliance with the applicable requirements of Part K.
1.3
Manufacturing processes
1.3.1
The requirements of this Section presume that welding and other cold or hot manufacturing processes are carriedout in compliance with current sound working practice defined in IACS UR W and the applicable requirements ofPart C and Part M. In particular:・ parent material and welding processes are to be within the limits stated for the specified type of material forwhich they are intended
・ specific preheating may be required before welding
・ welding or other cold or hot manufacturing processes may need to be followed by an adequate heat treatment.
2.

Hull structural steel

2.1
General
2.1.1
Table 1 gives the mechanical characteristics of steels currently used in the construction of ships.
Table 1

Mechanical properties of hull steels

Steel grades for plates

Minimum yield stress

Ultimate tensile strengthwith t £ 100 mm

ReH , in N/mm2

Rm , in N/mm2

A-B-D-E

235

400

520

AH32-DH32-EH32-FH32

315

440

570

AH36-DH36-EH36-FH36

355

490

630

AH40-DH40-EH40-FH40

390

510

660

2.1.2
Where higher strength steels are to be used for hull construction, the drawings showing the scope and locations of
the used place together with the type and scantlings are to be submitted for the approval of the Society.
2.1.3
Higher strength steels other than those indicated in Table 1 are considered by the Society on a case by case basis.
2.1.4
When steels with a minimum guaranteed yield stress ReH other than 235 N/mm2 are used on a ship, hull scantlings
are to be determined by taking into account the material factor k defined in 2.2.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

2.1.5
It is required to keep on board a plan indicating the steel types and grades adopted for the hull structures. Where
steels other than those indicated in Table 1 are used, their mechanical and chemical properties, as well as any
workmanship requirements or recommendations, are to be available on board together with the above plan.
2.2
Material factor k
2.2.1
Unless otherwise specified, the material factor k of normal and higher strength steel for scantling purposes is to betaken as defined in Table 2, as a function of the minimum yield stress ReH.
For intermediate values of ReH, k may be obtained by linear interpolation.
Steels with a yield stress greater than 390 N/mm2 are considered by the Society on a case by case basis.
Table 2

Material factor k

Minimum yield stress
ReH, in N/mm2

k

235

1.00

315

0.78

355

0.72

390

0.68

2.3
Grades of steel
2.3.1
Steel materials in the various strength members are not to be of lower grade than those corresponding to classes I,
II and III, as given in Table 3 for the material classes and grades given in Table 4-1, while in additional requirements
for ships with length (LCSR-B) exceeding 150m and 250m, BC-A and BC-B ships are given in Table 4-2 to Table 4-4.
For strength members not mentioned in Table 4-1 to Table 4-4, grade A/AH may be used.
2.3.2
Plating materials for stern frames, rudders, rudder horns and shaft brackets are in general not to be of lower grades
than corresponding to class II. For rudder and rudder body plates subjected to stress concentrations (e.g. in way oflower support of semi-spade rudders or at upper part of spade rudders) class III is to be applied.
2.3.3
Bedplates of seats for propulsion and auxiliary engines inserted in the inner bottom within 0.6LCSR-B amidships areto be of class I. In other cases, the steel is to be at least of grade A/AH.
2.3.4 (void)
2.3.5
The steel grade is to correspond to the as-built thickness.
2.3.6
Steel grades of plates or sections of as-built thickness greater than the limiting thicknesses in Table 3 areconsidered by the Society on a case by case basis.
2.3.7
In specific cases, such as 2.3.8, with regard to stress distribution along the hull girder, the classes required within
0.4LCSR-B amidships may be extended beyond that zone, on a case by case basis.
2.3.8
The material classes required for the strength deck plating, the sheerstrake and the upper strake of longitudinalbulkheads within 0.4LCSR-B amidships are to be maintained for an adequate length across the poop front and at theends of the bridge, where fitted.
2.3.9
Rolled products used for welded attachments of length greater than 0.15LCSR-B on outside of hull plating, such as
gutter bars, are to be of the same grade as that used for the hull plating in way.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

2.3.10In the case of full penetration welded joints located in positions where high local stresses may occur perpendicular
to the continuous plating, the Society may, on a case by case basis, require the use of rolled products having adequate
ductility properties in the through thickness direction, such as to prevent the risk of lamellar tearing (Z type steel).
Table 3

Material grade requirements for classes I, II and III

Class

I

As-built thickness
(mm)
t

III

NSS

HSS

NSS

HSS

NSS

HSS

A

AH

A

AH

A

AH

15 < t

20

A

AH

A

AH

B

AH

20 < t

25

A

AH

B

AH

D

DH

25 < t

30

A

AH

D

DH

D

DH

30 < t

35

B

AH

D

DH

E

EH

35 < t

40

B

AH

D

DH

E

EH

50

D

DH

E

EH

E

EH

40 < tNotes :15

II

NSS : Normal strength steel / HSS : Higher strength steel－39－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

Table 4-1

Material Classes and Grades for ships in general

Structural member category

Material class/grade

SECONDARY:
A1 Longitudinal bulkhead strakes, other than that belonging- Class I within 0.4LCSR-B amidships- Grade A/AH outside 0.4LCSR-B amidships

to the Primary category
A2 Deck plating exposed to weather, other than thatbelonging to the Primary or Special category
A3 Side plating
PRIMARY:
B1 Bottom plating, including keel plate- Class II within 0.4LCSR-B amidships

B2 Strength deck plating, excluding that belonging to the- Grade A/AH outside 0.4LCSR-B amidships

Special category
B3 Continuous longitudinal members above strength deck,
excluding hatch coamings
B4 Uppermost strake in longitudinal bulkhead
B5 Vertical strake (hatch side girder) and uppermost sloped
strake in top wing tank
SPECIAL:
C1 Sheer strake at strength deck(1)- Class III within 0.4LCSR-B amidships(1)

C2 Stringer plate in strength deck

- Class II outside 0.4LCSR-B amidships

C3 Deck strake at longitudinal bulkhead, excluding deck

- Class I outside 0.6LCSR-B amidships

plating in way of inner-skin bulkhead of double-hull
ships(1)C5 Strength deck plating at corners of cargo hatch openings- Class III within 0.6LCSR-B amidships- Class II within rest of cargo region

C6 Bilge strake in ships with double bottom over the fullbreadth and length less than 150m(1)- Class II within 0.6LCSR-B amidships- Class I outside 0.6LCSR-B amidships(1)

C7 Bilge strake in other ships- Class III within 0.4LCSR-B amidships- Class II outside 0.4LCSR-B amidships- Class I outside 0.6LCSR-B amidships

C8 Longitudinal hatch coamings of length greater than
C9 End brackets and deck house transition of longitudinalcargo hatch coamings(2)- Class III within 0.4LCSR-B amidships- Class II outside 0.4LCSR-B amidships

0.15LCSR-B- Class I outside 0.6LCSR-B amidships- Not to be less than Grade D/DH

Notes:(1) Single strakes required to be of Class III within 0.4LCSR-B amidships are to have breadths not less than 800+5LCSR-B (mm), andneed not be greater than 1,800(mm), unless limited by the geometry of the ship s design.
(2) Applicable to bulk carriers having the longitudinal hatch coaming of length greater than 0.15LCSR-B－40－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

Table 4-2

Minimum material grades for ships with ship s length (LCSR-B)
exceeding 150m and single strength deck

Structural member category

Material Grade

Longitudinal strength members of strength deck plating

Grade B/AH within 0.4LCSR-B amidships

Continuous longitudinal strength members above strength deck

Grade B/AH within 0.4LCSR-B amidships

Single side strakes for ships without inner continuous longitudinal

Grade B/AH within cargo region

bulkheads between bottom and the strength deck

Table 4-3

Minimum Material Grades for ships with ship s length (LCSR-B) exceeding 250m
Structural member category

Material Grade

Shear strake at strength deck (1)Grade E/EH within 0.4LCSR-B amidships

Stringer plate in strength deck (1)Grade E/EH within 0.4LCSR-B amidships

Bilge strake(1)

Grade D/DH within 0.4LCSR-B amidships

Note:(1) Single strakes required to be of Class III within 0.4LCSR-B amidships are to have breadths not less than 800 + 5LCSR-B(mm), and need not be greater than 1800 (mm), unless limited by the geometry of the ship s design

Table 4-4

Minimum material grades for BC-A and BC-B ships

Structural member category

Material Grade

Lower bracket of ordinary side frame(1), (2)Grade D/DHSide shell strakes included totally or partially between the two

Grade D/DH

points located to 0.125l above and below the intersection of side
shell and bilge hopper sloping plate or inner bottom plate (2)Notes:(1) The term lower bracket means webs of lower brackets and webs of the lower part of side frames up to the point
0.125l above the intersection of side shell and bilge hopper sloping plate or inner bottom plate.
(2) The span of the side frame, l, is defined as the distance between the supporting structure (See Ch 3, Sec 6, Fig.19)－41－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

2.4
Structures exposed to low air temperature
2.4.1
The application of steels for ships designed to operate in area with low air temperatures is to comply with 2.4.2 to
2.4.6.
2.4.2
For ships intended to operate in areas with low air temperatures (below and including 20 C), e.g. regular service
during winter seasons to Arctic or Antarctic waters, the materials in exposed structures are to be selected based on thedesign temperature tD , to be taken as defined in 2.4.3.
2.4.3
The design temperature tD is to be taken as the lowest mean daily average air temperature in the area of operation,
where:
Mean : Statistical mean over observation period (at least 20 years).
Average : Average during one day and night.
Lowest : Lowest during year.
Fig. 1 illustrates the temperature definition for Arctic waters.
For seasonally restricted service the lowest value within the period of operation applies.
Fig. 1

Commonly used definitions of temperatures
Mean daily maximum temperature
Mean daily average temperature

tD = design temperature
Mean daily minimum temperature－42－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

2.4.4
Materials in the various strength members above the lowest ballast water line (BWL) exposed to air are not to be oflower grades than those corresponding to classes I, II and III as given in Table 5 depending on the categories ofstructural members (SECONDARY, PRIMARY and SPECIAL).
For non-exposed structures and structures below the lowest ballast water line, see 2.3.
2.4.5
The material grade requirements for hull members of each class depending on thickness and design temperature aredefined in Table 6, Table 7 and Table 8. For design temperatures tD < -55 C, materials are to be speciallyconsidered by the Society.
2.4.6
Single strakes required to be of class III or of grade E/EH and FH are to have breadths not less than the values, in
m, given by the following formula, but need not to be greater than 1.8 m:
b = 0.005LCSR-B + 0.8
Table 5

Application of material classes and grades - Structures exposed at low temperature
Material class
Structural member category

WithinOutside0.4LCSR-B

0.4LCSR-B

amidshipamidship

I

I

II

I

III

II

SECONDARY
Deck plating exposed to weather, in general
Side plating above BWLTransverse bulkheads above BWLPRIMARY
Strength deck plating(1)Continuous longitudinal members above strength deck, excluding longitudinal hatch coamings
Longitudinal bulkhead above BWL
Top wing tank bulkhead above BWL
SPECIAL
Sheer strake at strength deck(2)Stringer plate in strength deck(2)Deck strake at longitudinal bulkhead(3)Continuous longitudinal hatch coamings(4)Notes:(1) Plating at corners of large hatch openings to be specially considered. Class III or grade E/EH to be applied in positions
where high local stresses may occur.
(2) Not to be less than grade E/EH within 0.4LCSR-B amidships in ships with length exceeding 250 m.
(3) In ships with a breadth exceeding 70 m at least three deck strakes to be class III.
(4) Not to be less than grade D/DH.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

Table 6As-built thickness(mm)t-20 / -25 C-26 / -35 C-36 / -45 C-45 / -55 C

NSS

HSS

NSS

HSS

NSS

HSS

NSS

HSS

A

AH

B

AH

D

DH

D

DH

10 < t

15

B

AH

D

DH

D

DH

D

DH

15 < t

20

B

AH

D

DH

D

DH

E

EH

20 < t

25

D

DH

D

DH

D

DH

E

EH

25 < t

30

D

DH

D

DH

E

EH

E

EH

30 < t

35

D

DH

D

DH

E

EH

E

EH

35 < t

45

D

DH

E

EH

E

EH

-

FH

45 < t

50

E

EH

E

EH

-

FH

-

FH

Note:

10

Material grade requirements for class I at low temperature

NSS and HSS mean, respectively Normal Strength Steel and Higher Strength Steel

Table 7As-built thickness

Material grade requirements for class II at low temperature-20 / -25 C-26 / -35 C-36 / -45 C-45 / -55 C

(mm)

NSS

HSS

NSS

HSS

NSS

HSS

NSS

HSS

t

B

AH

D

DH

D

DH

E

EH

10

10 < t

20

D

DH

D

DH

E

EH

E

EH

20 < t

30

D

DH

E

EH

E

EH

-

FH

30 < t

40

E

EH

E

EH

-

FH

-

FH

40 < t

45

E

EH

-

FH

-

FH

-

-

50

E

EH

-

FH

-

FH

-

-

45 < tNote:

NSS and HSS mean, respectively Normal Strength Steel and Higher Strength Steel

Table 8As-built thickness(mm)t-26 / -35 C-36 / -45 C-45 / -55 C

NSS

HSS

NSS

HSS

NSS

HSS

NSS

HSS

D

DH

D

DH

E

EH

E

EH

20

D

DH

E

EH

E

EH

-

FH

20 < t

25

E

EH

E

EH

-

FH

-

FH

25 < t

30

E

EH

E

EH

-

FH

-

FH

30 < t

40

E

EH

-

FH

-

FH

-

-

40 < t

45

E

EH

-

FH

-

FH

-

-

50

-

FH

-

FH

-

-

-

-

45 < t3.

-20 / -25 C

10 < tNote:

10Material grade requirements for class III at low temperature

NSS and HSS mean, respectively Normal Strength Steel and Higher Strength Steel

Steels for forging and casting

3.1
General3.1.1
Mechanical and chemical properties of steels for forging and casting to be used for structural members are tocomply with the applicable requirements of Part K.
3.1.2
Steels of structural members intended to be welded are to have mechanical and chemical properties deemed
appropriate for this purpose by the Society on a case by case basis.
3.1.3
The steels used are to be tested in accordance with the applicable requirements of Part K.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

3.2
Steels for forging
3.2.1
Rolled bars may be accepted in lieu of forged products, after consideration by the Society on a case by case basis.
In such case, compliance with the applicable requirements of Part K, relevant to the quality and testing of rolled
parts accepted in lieu of forged parts, may be required.
3.3
Steels for casting
3.3.1
Cast parts intended for stems, sternframes, rudders, parts of steering gear and deck machinery in general may bemade of C and C-Mn weldable steels, having specified minimum tensile strength Rm = 400 N/mm2 or 440 N/mm2, in
accordance with the applicable requirements of Part K.
3.3.2
The welding of cast parts to main plating contributing to hull strength members is considered by the Society on acase by case basis.
The Society may require additional properties and tests for such casting, in particular impact properties which areappropriate to those of the steel plating on which the cast parts are to be welded and non-destructive examinations.
3.3.3
Heavily stressed cast parts of steering gear, particularly those intended to form a welded assembly and tillers or
rotors mounted without key, are to be subjected to surface and volumetric non-destructive examination to check theirinternal structure.
4.

Aluminium alloy structures

4.1
General
4.1.1
The characteristics of aluminium alloys are to comply with the requirements of Part K.
Series 5000 aluminium-magnesium alloys or series 6000 aluminium-magnesium-silicon alloys are to be used.
4.1.2
In the case of structures subjected to low service temperatures or intended for other specific applications, the alloys
to be employed are to be agreed by the Society.
4.1.3
Unless otherwise agreed, the Young s modulus for aluminium alloys is equal to 70000 N/mm2 and the Poisson sratio equal to 0.33.
4.2
Extruded plating
4.2.1
Extrusions with built-in plating and stiffeners, referred to as extruded plating, may be used.
4.2.2
In general, the application is limited to decks, bulkheads, superstructures and deckhouses. Other uses may bepermitted by the Society on a case by case basis.
4.2.3
Extruded plating is to be oriented so that the stiffeners are parallel to the direction of main stresses.
4.2.4
Connections between extruded plating and primary members are to be given special attention.
4.3
Mechanical properties of weld joints
4.3.1
Welding heat input lowers locally the mechanical strength of aluminium alloys hardened by work hardening (series
5000 other than condition O or H111) or by heat treatment (series 6000).
4.3.2
The as-welded properties of aluminium alloys of series 5000 are in general those of condition O or H111.
Higher mechanical characteristics may be taken into account, provided they are duly justified.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

4.3.3
The as-welded properties of aluminium alloys of series 6000 are to be agreed by the Society.
4.4
Material factor k
4.4.1
The material factor k for aluminium alloys is to be obtained from the following formula:
235
k=
¢
Rlim
where:¢
R lim: Minimum guaranteed yield stress of the parent metal in welded condition R ¢p 0.2 , in N/mm2, but not tobe taken greater than 70% of the minimum guaranteed tensile strength of the parent metal in welded
condition R m¢ , in N/mm2
R¢p 0.2 = h1R p 0.2
Rm¢ = h2 Rm

Rp0.2 : Minimum guaranteed yield stress, in N/mm2, of the parent metal in delivery condition: Minimum guaranteed tensile strength, in N/mm2, of the parent metal in delivery conditionRmh1, h2 : Specified in Table 9.
4.4.2
In the case of welding of two different aluminium alloys, the material factor k to be considered for the scantlings is
the greater material factor of the aluminium alloys of the assembly.
Table 9

Aluminium alloys for welded construction
Aluminium alloyh1

h2

Alloys without work-hardening treatment (series 5000 in annealed condition O or1

1

Alloys hardened by work hardening (series 5000 other than condition O or H111)

R ¢p 0.2 / R p 0.2

Rm¢ / Rm

Alloys hardened by heat treatment (series 6000)(1)R ¢p 0.2 / R p 0.2

0.6

annealed flattened condition H111)

Notes:(1) When no information is available, coefficient h1 is to be taken equal to the metallurgical efficiency coefficient b
defined in Table 10.
R ¢p 0.2 : Minimum guaranteed yield stress, in N/mm2, of material in welded condition

Rm¢: Minimum guaranteed tensile strength, in N/mm2, of material in welded condition

Table 10

Aluminium alloys - Metallurgical efficiency coefficient b

Aluminium alloy
6005A (Open sections)
6005A (Closed sections)TemperGross thickness,conditionin mm

T5 or T6

t

b

6

0.45

t>6

0.40

T5 or T6

All

0.50

6061 (Sections)

T6

All

0.53

6082 (Sections)

T6

All

0.45

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 1)

5.

Other materials and products

5.1
General
5.1.1
Other materials and products such as parts made of iron castings, where allowed, products made of copper andcopper alloys, rivets, anchors, chain cables, cranes, masts, derrick posts, derricks, accessories and wire ropes are tocomply with the applicable requirements of Part K and Part L.
5.1.2
The use of plastics or other special materials not covered by Part K is to be considered by the Society on a case bycase basis. In such cases, the requirements for the acceptance of the materials concerned are to be agreed by theSociety.
5.1.3
Materials used in welding processes are to comply with the applicable requirements of Part K and Part M.
5.2
Iron cast parts
5.2.1
As a rule, the use of grey iron, malleable iron or spheroidal graphite iron cast parts with combined ferritic/perlitic
structure is allowed only to manufacture low stressed elements of secondary importance.
5.2.2
Ordinary iron cast parts may not be used for windows or sidescuttles; the use of high grade iron cast parts of asuitable type will be considered by the Society on a case by case basis.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 2)

Section 2

NET SCANTLING APPROACH

Symbols: As-built Thickness: the actual thickness, in mm, provided at the newbuilding stage, including
tvoluntary_addition, if any.
: Corrosion Addition Thickness: as defined in Ch 3, Sec 3, in mm.
tC
tgross_offered: Gross Thickness Offered: the actual gross (full) thickness, in mm, provided at the newbuilding stage,excluding tvoluntary_addition, the owner s extra margin for corrosion wastage, if any.
: Gross Thickness Required: the gross (full) thickness, in mm, obtained by adding tC to the Net
tgross_required
Thickness Required.
: Net Thickness Offered: the net thickness, in mm, obtained by subtracting tC from the Gross Thickness
tnet_offered
Offered: Net Thickness Required: the net thickness, in mm, as required by this Part that satisfy all the structural
tnet_required
strength requirements, rounded to the closest half millimetre.
tvoluntary_addition : Thickness for Voluntary Addition: the thickness, in mm, voluntarily added as the owner s extra
margin for corrosion wastage in addition to tC.
tas_built

1.

General philosophy

1.1
1.1.1
Net Scantling Approach is to clearly specify the net scantling that is to be maintained right from the newbuilding
stage throughout the ship s design life to satisfy the structural strength requirements. This approach clearly separates
the net thickness from the thickness added for corrosion that is likely to occur during the ship-in-operation phase.
2.

Application criteria

2.1
General2.1.1
The scantlings obtained by applying the criteria specified in this Part are net scantlings as specified in 3.1 to 3.3; i.e.
those which provide the strength characteristics required to sustain the loads, excluding any addition for corrosionand voluntarily added thickness such as the owner s extra margin, if any. The following gross offered scantlings are
exceptions; i.e. they already include additions for corrosion but without voluntarily added values such as the owner s
extra margin:・ scantlings of superstructures and deckhouses, according to Ch 9, Sec 4
・ scantlings of rudder structures, according to Ch 10, Sec 1
・ scantlings of massive pieces made of steel forgings, steel castings.
2.1.2
The required strength characteristics are:・ thickness, for plating including that which constitutes primary supporting members
・ section modulus, shear area, moments of inertia and local thickness for ordinary stiffeners and, as the case may
be, primary supporting members
・ section modulus, moments of inertia and first moment for the hull girder.
2.1.3
The ship is to be built at least with the gross scantlings obtained by adding the corrosion addition is, specified in
Ch 3, Sec 3, to the net scantlings. The thickness for voluntary additions may be added as an extra.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 2)

3.

Net scantling approach

3.1
Net scantling definition
3.1.1 Required thickness
The gross thickness required, tgross_required, is not less than the gross thickness which is obtained by adding thecorrosion addition tC as defined in Ch 3, Sec 3 to net thickness required, as follows:t gross _ required = t net _ required + t C
3.1.2 Offered thickness
The gross thickness offered, tgross_offered, is the gross thickness provided at the newbuilding stage, which is obtainedby deducting the thickness for voluntary addition from the as-built thickness, as follows:
tgross _ offered = tas _ built - tvoluntary _ addition
3.1.3 Net thickness for plate
Net thickness offered, tnet_offered, is obtained by subtracting tC from the gross thickness offered, as follows:tnet _ offered = t gross _ offered - tC = tas _ built - tvoluntary _ addition - tC
3.1.4 Net section modulus for stiffener
The net transverse section scantling is to be obtained by deducting tC from the gross thickness offered of theelements which constitute the stiffener profile as shown in Fig.1.
For bulb profiles, an equivalent angle profile, as specified in Ch 3, Sec 6, 4.1.1, may be considered.
The net strength characteristics are to be calculated for the net transverse section.
In assessing the net strength characteristics of stiffeners reflecting the hull girder stress and stress due to local
bending of the local structure such as double bottom structure, the section modulus of hull girder or rigidity ofstructure is obtained by deducting 0.5tC from the gross thickness offered of the related elements.
Fig. 1

Net scantling of stiffeners

bf

tf

hw
tw

tp

bp

Shadow area is corrosion addition.
For attached plate, the half of the considered corrosion addition specified in 3.2 is deducted from both sides of
the attached plate.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 2)

3.2
Considered net scantling
3.2.1 Yielding check of the hull girder
The net thickness of structural members to be considered for the yielding check of the hull girder, according to Ch
5, Sec 1, is to be obtained by deducting 0.5tC from the gross thickness offered.
3.2.2 Global stress such as stress due to hull girder bending moment and shear force
The net thickness of structural members to be considered for stress due to hull girder bending moment and shear
force according to Ch 5, Sec 1, is to be obtained by deducting 0.5tC from the gross thickness offered.
3.2.3 Buckling check of the hull girder
The net thickness of structural members to be considered for the buckling check, according to Ch 6, Sec 3, is to beobtained by deducting tC from the gross thickness offered.
3.2.4 Ultimate strength check of the hull girder
The net thickness of structural members to be considered for the ultimate strength check of the hull girder,
according to Ch 5, Sec 2, is to be obtained by deducting 0.5tC from the gross thickness offered.
3.2.5 Direct strength analysis
The net thickness of plating which constitutes primary supporting members to be checked stresses according to Ch
7 is to be obtained by deducting 0.5tC from the gross thickness offered.
The net thickness of plating members to be considered for the buckling check according to Ch 6, Sec 3, using thestresses obtained from direct strength analysis, is to be obtained by deducting tC from the gross thickness offered.
3.2.6 Fatigue check
The net thickness of structural members to be checked for fatigue according to Ch 8 is to be obtained by deducting
0.5tC from the gross thickness offered.
3.2.7 Check of primary supporting members for ships less than 150m in length LCSR-B
The net thickness of plating which constitutes primary supporting members for ships less than 150m in length
LCSR-B, to be checked according to Ch 6, Sec 4, 2, is to be obtained by deducting tC from the gross thickness.
3.3
Available information on structural drawings
3.3.1
The structural drawings are to indicate for each structural element the gross scantling and the renewal thickness as
specified in Ch 13, Sec 2.
If thickness for voluntary addition is included in the as-built thicknesses, this is to be clearly mentioned andidentified on the drawings.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 3)

Section 3

CORROSION ADDITIONS

Symbols: Total corrosion addition, in mm, defined in 1.2
tC
tC1, tC2 : Corrosion addition, in mm, on one side of the considered structural member, defined in Table 1
treserve : Reserve thickness, in mm, defined in Ch 13, Sec 2 and taken equal to:t reserve = 0.5

1.

Corrosion additions

1.1
General1.1.1
The values of the corrosion additions specified in this section are to be applied in relation with the relevant
protective coatings required by Sec 5.
For materials different from carbon steel, special consideration is to be given to the corrosion addition.
1.2
Corrosion addition determination
1.2.1 Corrosion additions for steel
The corrosion addition for each of the two sides of a structural member, tC1 or tC2, is specified in Table 1.
The total corrosion addition tC, in mm, for both sides of the structural member is obtained by the following
formula:tC = Roundup0.5 (tC1 + tC 2 ) + treserve
For an internal member within a given compartment, the total corrosion addition tC is obtained from the following
formula:tC = Roundup0.5 (2tC1 ) + treserve
where tC1 is the value specified in Table 1 for one side exposure to that compartment.
When a structural member is affected by more than one value of corrosion addition (e.g. a plate in a dry bulk cargohold extending above the lower zone), the scantling criteria are generally to be applied considering the severest valueof corrosion addition applicable to the member.
The corrosion addition of a longitudinal stiffener is determined according to the coordinate of the connection of thestiffener to the attached plating.
In addition, the total corrosion addition tC is not to be taken less than 2 mm, except for web and face plate ofordinary stiffeners.
1.2.2 Corrosion additions for aluminium alloys
For structural members made of aluminium alloys, the corrosion addition tC is to be taken equal to 0.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 3)

Table 1

Corrosion addition on one side of structural members
Corrosion addition, tC1 or tC2, in mm

Compartment

BC-A or BC-B

Structural member

Type

LCSR-B
Ballast watertank(2)

150 m

(3)

Face plate ofWithin 3 m below the top of tankprimary members

Elsewhere

1.5

Within 3 m below the top of tank(3)1.7

Other members

2.0

Elsewhere

1.2

Upper part(4)Transverse bulkhead

2.4

1.0

5.2

2.6

3.0

1.5

1.8

1.0

2.2

1.2

Other parts

2.0

1.2

Continuous wooden ceiling

2.0

1.2

No continuous wooden ceiling

3.7

2.4

Lower stool : sloping plate, verticalplate and top plate
Other parts
Upper part

(4)

Webs and flanges of the upper end
brackets of side frames of single

Dry bulk cargohold(1)Other

ships withside bulk carriers

Other members

Webs and flanges of lower brackets
of side frames of single side bulk
carriers

Sloped plating of
hopper tank, inner
bottom plating
Exposed to

Horizontal member and weather deck(5)1.7atmosphere

Non horizontal member

1.0

(7)

1.0

Exposed to sea water(2)

Fuel oil tanks and lubricating oil tanks

0.7

Fresh water tanks

0.7

Void spaces(6)Dry spaces

Spaces not normally accessed, e.g. access only throughbolted manholes openings, pipe tunnels, etc.
Internal of deck houses, machinery spaces, stores spaces,
pump rooms, steering spaces, etc.

Other compartments than above

0.7
0.5
0.5

Notes
(1) Dry bulk cargo hold includes holds, intended for the carriage of dry bulk cargoes, which may carry water ballast.
(2) The corrosion addition of a plating between water ballast and heated fuel oil tanks is to be increased by 0.7 mm.
(3) This is only applicable to ballast tanks with weather deck as the tank top.
(4) Upper part of the cargo holds corresponds to an area above the connection between the top side and the inner hull or side
shell. If there is no top side, the upper part corresponds to the upper one third of the cargo hold height.
(5) Horizontal member means a member making an angle up to 20 as regard as a horizontal line.
(6) The corrosion addition on the outer shell plating in way of pipe tunnel is to be considered as water ballast tank.
(7) Outer side shell between normal ballast draught and scantling draught is to be increased by 0.5 mm.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 4)

Section 4
1.

LIMIT STATESGeneral

1.1
General principle
1.1.1
The structural strength assessments indicated in Table 1 are covered by the requirements of this Part.
Table 1

Structural strength assessment
Yielding

Buckling

Ultimate

check

check

strength check

Local

Ordinary stiffeners

ü

ü

ü(1)

Structures

Plating subjected to lateral pressure

ü

ü

ü(3)

Primary supporting members

ü

ü

ü

Hull girder

ü

ü(4)

ü

Fatigue check
ü(2)

ü(2)

Note: ü indicates that the structural assessment is to be carried out.
(1) The ultimate strength check of stiffeners is included in the buckling check of stiffeners.
(2) The fatigue check of stiffeners and primary supporting members is the fatigue check of connection details of thesemembers.
(3) The ultimate strength check of plating is included in the yielding check formula of plating.
(4) The buckling check of stiffeners and plating taking part in hull girder strength is performed against stress due to hull girder
bending moment and hull girder shear force.

1.1.2
Strength of hull structures in flooded condition is to be assessed.
1.2
Limit states
1.2.1 Serviceability limit state
Serviceability limit state, which concerns the normal use, includes:
・ local damage which may reduce the working life of the structure or affect the efficiency or appearance ofstructural members
・ unacceptable deformations which affect the efficient use and appearance of structural members or thefunctioning of equipment.
1.2.2 Ultimate limit state
Ultimate limit state, which corresponds to the maximum load-carrying capacity, or in some cases, the maximum
applicable strain or deformation, includes:
・ attainment of the maximum resistance capacity of sections, members or connections by rupture or excessive
deformations
・ instability of the whole structure or part of it.
1.2.3 Fatigue limit state
Fatigue limit state relate to the possibility of failure due to cyclic loads.
1.2.4 Accidental limit state
Accidental limit state considers the flooding of any one cargo hold without progression of the flooding to the othercompartments and includes:
・ the maximum load-carrying capacity of hull girder・ the maximum load-carrying capacity of double bottom structure
・ the maximum load-carrying capacity of bulkhead structure
Accidental single failure of one structural member of any one cargo hold is considered in the assessment of theultimate strength of the entire stiffened panel.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 4)

2.

Strength criteria

2.1Serviceability limit states
2.1.1 Hull girder
For the yielding check of the hull girder, the stress corresponds to a load at 10-8 probability level.
2.1.2 Plating
For the yielding check and buckling check of platings constituting a primary supporting member, the stresscorresponds to a load at 10-8 probability level.
2.1.3 Ordinary stiffener
For the yielding check of an ordinary stiffener, the stress corresponds to a load at 10-8 probability level.
2.2
Ultimate limit states
2.2.1 Hull girder
The ultimate strength of the hull girder is to withstand the maximum vertical longitudinal bending moment
obtained by multiplying the partial safety factor and the vertical longitudinal bending moment at 10-8 probability
level.
2.2.2 Plating
The ultimate strength of the plating between ordinary stiffeners and primary supporting members is to withstandthe load at 10-8 probability level.
2.2.3 Ordinary stiffener
The ultimate strength of the ordinary stiffener is to withstand the load at 10-8 probability level.
2.3
Fatigue limit state
2.3.1 Structural details
The fatigue life of representative structural details such as connections of ordinary stiffeners and primary
supporting members is obtained from reference pressures at 10-4.
2.4
Accidental limit state
2.4.1 Hull girderLongitudinal strength of hull girder in cargo hold flooded condition is to be assessed in accordance with Ch 5, Sec2.
2.4.2 Double bottom structure
Double bottom structure in cargo hold flooded condition is to be assessed in accordance with Ch 6, Sec 4.
2.4.3 Bulkhead structure
Bulkhead structure in cargo hold flooded condition is to be assessed in accordance with Ch 6, Sec 1, Sec 2 andSec 3.
3.

Strength check against impact loads

3.1
General
3.1.1
Structural response against impact loads such as forward bottom slamming, bow flare slamming and grab falling
depends on the loaded area, magnitude of loads and structural grillage.
3.1.2
The ultimate strength of structural members that constitute the grillage, i.e. platings between ordinary stiffeners
and primary supporting members and ordinary stiffeners with attached plating, is to withstand the maximum impact
loads acting on them.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 5)

Section 5
1.

CORROSION PROTECTION

General

1.1
Structures to be protected
1.1.1
All seawater ballast tanks, cargo holds and ballast holds are to have a corrosion protective system fitted inaccordance with 1.2, 1.3 and 1.4 respectively.
1.1.2
Void double side skin spaces in cargo length area for vessels having a length (LLL) of not less than 150 m are to becoated in accordance with 1.2.
1.1.3
Corrosion protective coating is not required for internal surfaces of spaces intended for the carriage of fuel oil.
1.1.4
Narrow spaces are generally to be filled by an efficient protective product, particularly at the ends of the ship
where inspections and maintenance are not easily practicable due to their inaccessibility.
1.2
Protection of seawater ballast tanks and void double side skin spaces
1.2.1
All dedicated seawater ballast tanks anywhere on the ship (excluding ballast hold) for vessels having a length(LCSR-B) of not less than 90m and void double side skin spaces in the cargo length area for vessels having a length(LLL) of not less than 150m are to have an efficient corrosion prevention system, such as hard protective coatings orequivalent, applied in accordance with the manufacturer s recommendation.
The coatings are to be of a light colour, i.e. a colour easily distinguishable from rust which facilitates inspection.
Where appropriate, sacrificial anodes, fitted in accordance with 2, may also be used.
1.2.2
For ships contracted for construction on or after 8 December 2006, the date of IMO adoption of the amended
SOLAS regulation II-1/3-2, by which an IMO Performance standard for protective coatings for ballast tanks and void
spaces will be made mandatory, the coatings of internal spaces subject to the amended SOLAS regulation are tosatisfy the requirements of the IMO performance standard. For ships contracted for construction on or after 1 July
2012, the IMO performance standard is to be applied as interpreted by IACS UI SC 223 and UI SC 227. In applying
IACS UI SC 223, Administration is to be read to be the Classification Society .
Consistent with IMO Resolution A.798(19) and IACS UI SC 122, the selection of the coating system, including
coating selection, specification, and inspection plan, are to be agreed between the shipbuilder, coating system
supplier and the owner, in consultation with the Society, prior to commencement of construction. The specification
for the coating system for these spaces is to be documented and this documentation is to be verified by the Society
and is to be in full compliance with the coating performance standard.
The shipbuilder is to demonstrate that the selected coating system with associated surface preparation andapplication methods is compatible with the manufacturing processes and methods.
The shipbuilder is to demonstrate that the coating inspectors have proper qualification as required by the IMO
standard.
The attending surveyor of the Society will not verify the application of the coatings but will review the reports ofthe coating inspectors to verify that the specified shipyard coating procedures have been followed.
1.3
Protection of cargo hold spaces
1.3.1 Coating
It is the responsibility of the shipbuilder and of the owner to choose coatings suitable for the intended cargoes, inparticular for the compatibility with the cargo.
1.3.2 Application
All internal and external surfaces of hatch coamings and hatch covers, and all internal surfaces of cargo holds (sideand transverse bulkheads), excluding the inner bottom area and part of the hopper tank sloping plate and lower stool－55－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 5)

sloping plate, are to have an efficient protective coating, of an epoxy type or equivalent, applied in accordance withthe manufacturer s recommendation.
The side and transverse bulkhead areas to be coated are specified in 1.3.3 and 1.3.4 respectively.
1.3.3 Side areas to be coated
The areas to be coated are the internal surfaces of:・ the inner side plating
・ the internal surfaces of the topside tank sloping plates
・ the internal surfaces of the hopper tank sloping plates for a distance of 300 mm below the frame end bracket forholds of single side skin construction, or below the hopper tank upper end for holds of double side skinconstruction.
These areas are shown in Fig. 1.
Fig. 1

Side areas to be coated

1.3.4 Transverse bulkhead areas to be coated
The areas of transverse bulkheads to be coated are all the areas located above a horizontal level located at a
distance of 300 mm below the frame end bracket for holds of single side skin construction, or below the hopper tankupper end for holds of double side skin construction.
1.4
Protection of ballast hold spaces
1.4.1 Application
All internal and external surfaces of hatch coamings and hatch covers, and all internal surfaces of ballast holds areto have an effective protective coating, of an epoxy type or equivalent, applied in accordance with the manufacturer s
recommendation.
2.

Sacrificial anodes

2.1
General2.1.1
Anodes are to have steel cores and are to be fitted sufficiently rigid by the anode support designed so that theyretain the anode even when it is wasted.
The steel inserts are to be attached to the structure by means of a continuous weld. Alternatively, they may be
attached to separate supports by bolting, provided a minimum of two bolts with lock nuts are used. However, othermechanical means of clamping may be accepted.
2.1.2
The supports at each end of an anode may not be attached to separate items which are likely to moveindependently.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 5)

2.1.3
Where anode inserts or supports are welded to the structure, the welds are to be smoothly.
3.

Protection of inner bottom by ceiling

3.1
General3.1.1
Ceiling on the inner bottom, if any, is to comply with 3.2 and 3.3.
3.2
Arrangement
3.2.1
Planks forming ceiling over the bilges and on the inner bottom are to be easily removable to permit access formaintenance.
3.2.2
Where the double bottom is intended to carry fuel oil, ceiling on the inner bottom is to be separated from theplating by means of battens 30 mm high, in order to facilitate the drainage of oil leakages to the bilges.
3.2.3
Where the double bottom is intended to carry water, ceiling on the inner bottom may lie next to the plating,provided a suitable protective composition is applied beforehand.
3.2.4
The shipyard is to take care that the attachment of ceiling does not affect the tightness of the inner bottom.
3.3
Scantlings
3.3.1
The thickness of ceiling boards, when made of pine, is to be not less than 60 mm. Under cargo hatchways, thethickness of ceiling is to be increased by 15 mm.
Where the floor spacing is large, the thicknesses may be considered by the Society on a case by case basis.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

Section 6

STRUCTURAL ARRANGEMENT PRINCIPLES

Symbols
For symbols not defined in this Section, refer to the list defined in Ch 1, Sec 4.
bh : Breadth, in m, of cargo hatch opening
lb : Length, in m, of the free edge of the end bracket.

1.

Application

If not specified otherwise, the requirements of this section apply to the hull structure except superstructures anddeckhouses. For areas outside the cargo holds area, supplementary requirements are to be found in Ch 9, Sec 1 to
Ch 9, Sec 3.
2.

General principles

2.1
Definition
2.1.1 Primary frame spacing
Primary frame spacing, in m, is defined as the distance between the primary supporting members.
2.1.2 Secondary frame spacing
Secondary frame spacing, in m, is defined as the distance between ordinary stiffeners.
2.2
Structural continuity
2.2.1 General
The reduction in scantling from the midship part to the end parts is to be effected as gradually as practicable.
Attention is to be paid to the structural continuity in way of changes in the framing system, at the connections ofprimary supporting members or ordinary stiffeners and in way of the ends of the fore and aft parts and machinery
space and in way of the ends of superstructures.
2.2.2 Longitudinal members
Longitudinal members are to be so arranged as to maintain the continuity of strength.
Longitudinal members contributing to the hull girder longitudinal strength are to extend continuously for a
sufficient distance towards the end of ship.
In particular, the continuity of the longitudinal bulkheads, including vertical and horizontal primary supporting
members, extended over the cargo hold area is to be ensured beyond the cargo hold area. Scarfing brackets are apossible means.
2.2.3 Primary supporting members
Primary supporting members are to be arranged in such a way that they ensure adequate continuity of strength.
Abrupt changes in height or cross section are to be avoided.
2.2.4 Ordinary stiffeners
Ordinary stiffeners contributing to the hull girder longitudinal strength are generally to be continuous whencrossing primary supporting members.
2.2.5 Platings
A change in plating thickness in as-built is not to exceed 50% of thicker plate thickness for load carrying direction.
The butt weld preparation is to be in accordance with the requirements of Ch 11, Sec 2, 2.2.
2.2.6 Stress concentrations
Where stress concentration may occur in way of structural discontinuity, sufficient consideration is to be paid to
reduce the stress concentration and adequate compensation and reinforcements are to be provided.
Openings are to be avoided, as far as practicable, in way of highly stressed areas.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

Where openings are arranged, the shape of openings is to be such that the stress concentration remains within
acceptable limits.
Openings are to be well rounded with smooth edges.
Weld joints are to be properly shifted from places where the stress may highly concentrate.
2.3
Connections with higher tensile steel
2.3.1 Connections with higher tensile steel
Where steels of different strengths are mixed in a hull structure, due consideration is to be given to the stress in thelower tensile steel adjacent to higher tensile steel.
Where stiffeners of lower tensile steel are supported by primary supporting members of higher tensile steel, dueconsideration is to be given to the stiffness of primary supporting members and scantlings to avoid excessive stress inthe stiffeners due to the deformation of primary supporting members.
Where higher tensile steel is used at deck structures and bottom structure, longitudinal members not contributing to
the hull girder longitudinal strength and welded to the strength deck or bottom plating and bilge strake, such as
longitudinal hatch coamings, gutter bars, strengthening of deck openings, bilge keel, etc., are to be made of the same
higher tensile steel. The same requirement is generally applicable for non continuous longitudinal stiffeners weldedon the web of a primary member contributing to the hull girder longitudinal strength as hatch coamings, stringers andgirders.
3.

Plating

3.1
Structural continuity of plating
3.1.1 Insert plate
Where a local increase in plating thickness is generally to be achieved to through insert plates, an insert plate is to
be made of the materials of a quality (yield & grade) at least equal to that of the plates on which they are welded.
4.

Ordinary stiffener

4.1
Profile of stiffeners
4.1.1 Stiffener profile with a bulb section
The properties of bulb profile sections are to be determined by exact calculations. If it is not possible, a bulb
section may be taken as equivalent to a built-up section. The dimensions of the equivalent angle section are to beobtained, in mm, from the following formulae.
h¢h w = h w¢ - w + 2
9 .2
h¢
æ
ö
b f = a çç t w¢ + w - 2
6
.
7
è
ø
h w¢
-2
tf =
9 .2
where:hw¢ , t ¢w : Height and net thickness of a bulb section, in mm, as shown in Fig. 1.

a: Coefficient equal to:(120 - hw¢ )2
a = 1 .1 +3000
a = 1 .0

for h w¢ £ 120
for h w¢ > 120－59－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

Fig. 1

Dimensions of stiffeners

4.2
Span of ordinary stiffeners
4.2.1 Ordinary stiffener
The span l of ordinary stiffeners is to be measured as shown in Fig. 2. For curved stiffeners, the span is measured
along the chord.
Fig. 2

Fig. 3

Span of ordinary stiffeners

Span of ordinary stiffeners within a double hull

4.2.2 Ordinary stiffener within a double hull
The span l of ordinary stiffeners fitted inside a double hull, i.e. when the web of the primary supporting members
is connected with the inner hull and the outer shell acting as its flanges, is to be measured as shown in Fig. 3.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

4.2.3 Ordinary stiffeners supported by struts
The arrangement of ordinary stiffeners supported by struts is not allowed for ships over 120 m in length.
The span l of ordinary stiffeners supported by one strut fitted at mid distance of the primary supporting members is
to be taken as 0.7l2.
In case where two struts are fitted between primary supporting members, the span l of ordinary stiffeners is to betaken as the greater of 1.4l1 and 0.7l2.
l1 and l2 are the spans defined in Figs. 4 and 5.
Fig. 4

Span of ordinary stiffeners with one strut

l2
l1

Fig. 5

Span of ordinary stiffeners with two struts

l2
l1

4.3
Attached plating
4.3.1 Effective breadth for yielding check
The effective width bp of the attached plating to be considered in the actual net section modulus for the yielding
check of ordinary stiffeners is to be obtained, in m, from the following formulae:
・ where the plating extends on both sides of the ordinary stiffener:
bp = 0.2l , or
bp = swhichever is lesser.
・ where the plating extends on one side of the ordinary stiffener (i.e. ordinary stiffeners bounding openings):b p = 0 .5 s
bp = 0.1l

whichever is lesser.
4.3.2 Effective width for buckling check
The effective width of the attached plating of ordinary stiffeners for checking the buckling of ordinary stiffeners isdefined in Ch 6, Sec 3, 5.

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4.4
Geometric property of ordinary stiffeners
4.4.1 General
Geometric properties of stiffeners such as moment of inertia, section modulus, shear sectional area, slenderness
ratio of web plating, etc., are to be calculated based on the net thickness as defined in Ch 3, Sec 2.
4.4.2 Stiffener not perpendicular to the attached plating
The actual stiffener s net section modulus is to be calculated about an axis parallel to the attached plating.
Where the stiffener is not perpendicular to the attached plating, the actual net section modulus can be obtained, in
cm3, from the following formula:w = w0 sin awhere:
w0 : Actual net section modulus, in cm3, of the stiffener assumed to be perpendicular to the attached platinga : Angle, in degrees, between the stiffener web and the attached plating, as shown in Fig. 6, but not to betaken less than 50.
The correction is to be applied when is between 50 and 75 degrees.
Where the angle between the web plate of stiffener and the attached plating is less than 50 degrees, tripping
bracket is to be fitted at suitable spacing. If the angle between the web plate of an unsymmetrical stiffener and theattached plating is less than 50 degrees, the face plate of the stiffener is to be fitted on the side of open bevel, as
shown in Fig. 7.
Fig. 6

Fig. 7

Angle between stiffener web and attached plating

Orientation of stiffener when the angle is less than 50 degrees

4.5
End connections of ordinary stiffeners
4.5.1 General
Where ordinary stiffeners are to be continuous through primary supporting members, they are to be properly
connected to the web plating so as to ensure proper transmission of loads. Some sample connections are shown in Fig.
8 to Fig. 11.

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Fig. 8(a) Connection without collar plate and(b) Connection with stiffener at side of longitudinal(a)Fig. 9(b)Connection with collar plate

Fig. 10Connection with one large collar plate

Fig. 11

Connection with two large collar plates

4.5.2 Structural continuity of stiffeners
Where ordinary stiffeners are cut at primary supporting members, brackets are to be fitted to ensure structuralcontinuity. In this case, the net section modulus and net sectional area of the brackets are to be not less than those of
the ordinary stiffener.
The minimum net thickness of brackets is to be not less than that required for web plate of ordinary stiffeners.
The brackets are to be flanged or stiffened by a welded face plate where:
・ the net thickness of the bracket, in mm, is less than 15lb, where lb is the length, in m, of the free edge of the end
bracket or brackets; or・ the longer arm of the bracket is greater than 800 mm.
The net sectional area, in cm2, of the flanged edge or faceplate is to be at least equal to 10lb.
4.5.3 End connections
End connection of stiffeners is to be sufficiently supported by the primary supporting members. Generally, a
stiffener or a bracket to support the ordinary stiffener is to be provided.
Where slots for penetration of stiffeners are reinforced with collars, they are to be of the same materials as theprimary supporting members.
Brackets or stiffeners to support the ordinary stiffeners are to be of sufficient sectional area and moment of inertia
with respect to structural continuity, and are to have appropriate shape with respect to fatigue strength. If brackets or－63－

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stiffeners to support the ordinary stiffeners are not fitted, or special slot configurations considering the fatigue
strength are provided, fatigue strength assessment for slots are required by the Society.
5.

Primary supporting members

5.1
General5.1.1
Primary supporting members are to be arranged in such a way that they ensure adequate continuity of strength.
Abrupt changes in height or in cross-section are to be avoided.
5.1.2
Where arrangements of primary supporting members are ensured adequate based on the results of FE analysis,
fatigue assessment and ultimate strength assessment, primary supporting members are to be arranged in accordancewith the result of such assessment.
5.2
Stiffening arrangement
5.2.1
Webs of primary supporting members are to be stiffened where the height, in mm, is greater than 100t, where t is
the net web thickness, in mm, of the primary supporting member.
In general, the web stiffeners of primary supporting members are to be spaced not more than 110t.
The net thickness of web stiffeners and brackets, in mm, are not to be less than the value obtained from thefollowing formula:t = 3 + 0.015L2
where:
L2 : Rule length LCSR-B, but to be taken not greater than 300 m
Additional stiffeners are to be fitted in way of end brackets, at the connection with cross ties, etc. of transverse
primary supporting members where shearing stress and/or compressive stress is expected to be high. These parts are
not to have holes. Cut outs for penetration of ordinary stiffeners in these parts are to be reinforced with collar plates.
Depth of stiffener of flat bar type is in general to be more than 1/12 of stiffener length. A smaller depth of stiffener
may be accepted based on calculations showing compliance with Ch 6, Sec 2, 2.3.1, Ch 6, Sec 2, 4 and Ch 6, Sec 3,
4.
5.2.2
Tripping brackets (see Fig 12) welded to the face plate are generally to be fitted:
・ at every fourth spacing of ordinary stiffeners, without exceeding 4 m.
・ at the toe of end brackets
・ at rounded face plates
・ in way of concentrated loads
・ near the change of section.
Where the width of the symmetrical face plate is greater than 400 mm, backing brackets are to be fitted in way of
the tripping brackets.
Where the face plate of the primary supporting member exceeds 180 mm on either side of the web, tripping bracket
is to support the face plate as well.
Fig. 12

Primary supporting member: web stiffener in way of ordinary stiffener－64－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

5.2.3
The width of face plate of the primary supporting member except ring shape such as transverse ring in bilge hoppertanks and top side tank is to be not less than one tenth of the depth of the web, where tripping brackets are spaced as
specified in 5.2.2.
5.2.4
The arm length of tripping brackets is to be not less than the greater of the following values, in m:
d = 0.38b
d = 0.85

sttwhere:b : Height, in m, of tripping brackets, shown in Fig. 12
st : Spacing, in m, of tripping brackets
t : Net thickness, in mm, of tripping brackets.
5.2.5
Tripping brackets with a net thickness, in mm, less than 10lb are to be flanged or stiffened by a welded face plate.
The net sectional area, in cm2, of the flanged edge or the face plate is to be not less than 7lb, where lb is the length,
in m, of the free edge of the bracket.
Where the height or breadth of tripping brackets is greater than 3 m, an additional stiffener is to be fitted parallel tothe bracket free edge.
5.3
Span of primary supporting members
5.3.1 Definitions
The span l, in m, of a primary supporting member without end bracket is to be taken as the length of the member
between supports.
The span l, in m, of a primary supporting member with end brackets is taken between points where the depth of
the bracket is equal to half the depth of the primary supporting member as shown in Fig. 13(a).
However, in case of curved brackets where the face plate of the member is continuous along the face of the bracket,
as shown in Fig. 13(b), the span is taken between points where the depth of the bracket is equal to one quarter thedepth of the primary supporting member.
Fig. 13

Span of primary support member

l

d

d /4

d /2

d

l

(a)

(b)

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5.4
Effective breadth of primary supporting member
5.4.1 General
The effective breadth bp of the attached plating of a primary supporting member to be considered in the actual net
section modulus for the yielding check is to be determined according to 4.3.1.
5.5
Geometric properties
5.5.1 General
Geometric properties of primary supporting members such as moment of inertia, section modulus, shear sectionalarea, slenderness ratio of web plating, etc., are to be calculated based on the net thickness as specified in Ch 3, Sec 2.
5.6
Bracketed end connection
5.6.1 General
Where the ends of the primary supporting members are connected to bulkheads, inner bottom, etc., the end
connections of all primary supporting members are to be balanced by effective supporting members on the opposite
side of bulkheads, inner bottoms, etc.
Tripping brackets are to be provided on the web plate of the primary supporting members at the inner edge of end
brackets and connection parts of the other primary supporting members and also at the proper intervals to support the
primary supporting members effectively.
5.6.2 Dimensions of brackets
Arm length of bracket is generally not to be less than one-eighth of span length of the primary member, unlessotherwise specified. Arm lengths of brackets at both ends are to be equal, as far as practicable.
The height of end brackets is to be not less than that of the primary supporting member. The net thickness of theend bracket web is not to be less than that of the web plate of the primary supporting member.
The scantlings of end brackets are to be such that the section modulus of the primary supporting member with end
brackets is not less than that of the primary supporting member at mid-span point.
The width, in mm, of the face plate of end brackets is to be not less than 50(lb+1).
Moreover, the net thickness of the face plate is to be not less than that of the bracket web.
Stiffening of end brackets is to be designed such that it provides adequate buckling web stability.
The following prescriptions are to be applied:
・ where the length lb is greater than 1.5 m, the web of the bracket is to be stiffened
・ the net sectional area, in cm2, of web stiffeners is to be not less than 16.5l, where l is the span, in m, of thestiffener
・ tripping flat bars are to be fitted to prevent lateral buckling of web stiffeners. Where the width of thesymmetrical face plate is greater than 400 mm, additional backing brackets are to be fitted.
Fig. 14

Dimension of bracketslb
Arm length(Bracket height)

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5.7
Cut-outs and holes
5.7.1
Cut-outs for the passage of ordinary stiffeners are to be as small as possible and well rounded with smooth edges.
The depth of cut-outs is to be not greater than 50% of the depth of the primary supporting member.
5.7.2
Where openings such as lightening holes are cut in primary supporting members, they are to be equidistant fromthe face plate and corners of cut-outs and, in general, their height is to be not greater than 20% of the web height.
Where lightening holes with free edges are provided, the dimensions and locations of lightening holes are
generally to be as shown in Fig. 15.
Where lightening holes are cut in the brackets, the distance from the circumference of the hole to the free flange ofbrackets is not to be less than the diameter of the lightening hole.
Fig. 15

Location and dimensions of lightening holesjjj £ d / 4, h £ d / 2, a ³ jj £ d / 3, h £ d / 2

without collar plate

5.7.3
Openings are not be fitted in way of toes of end brackets.
5.7.4
At the mid-part within 0.5 times of the span of primary supporting members, the length of openings is to be notgreater than the distance between adjacent openings.
At the ends of the span, the length of openings is to be not greater than 25% of the distance between adjacent
openings.
5.7.5
In the case of large openings in the web of primary supporting members (e.g. where a pipe tunnel is fitted in the
double bottom), the secondary stresses in primary supporting members are to be considered for the reinforcement of
the openings.
This may be carried out by assigning an equivalent net shear sectional area to the primary supporting member
obtained, in cm2, according from the following formula:
Ash1
Ash 2
As h =+
0.0032l 2 Ash1
0.0032l 2 Ash 2
1+
1+
I1
I2
where (see Fig. 16):
I1, I2: Net moments of inertia, in cm4, of deep webs (1) and (2), respectively, with attached platingaround their neutral axes parallel to the plating
Ash1, Ash2 : Net shear sectional areas, in cm2, of deep webs (1) and (2), respectively, taking account of the
web height reduction by the depth of the cut out for the passage of the ordinary stiffeners, if anyl: Span, in cm, of deep webs (1) and (2).

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Fig. 166.

Large openings in the web of primary supporting members

Double bottom

6.1
General6.1.1 Double bottom extend
Ref. SOLAS Ch. II-1, Part B, Reg. 12-1
A double bottom is to be fitted extending from the collision bulkhead to the afterpeak bulkhead.
6.1.2 Framing system
For ships greater than 120 m in length, the bottom, the double bottom and the sloped bulkheads of hopper tanks areto be of longitudinal system of frame arrangement at least within the cargo hold area. The spacing of the floors andbottom girders is not only governed by frame spaces but requirement in absolute value, in m, is also indicated in 6.3.3
and 6.4.1.
6.1.3 Height of double bottom
Where a double bottom is required to be fitted the inner bottom shall be continued transversely in such a manner as
to protect the bottom to the turn of the bilge.
Such protection will be deemed satisfactory if the inner bottom is not lower at any part than a plane parallel withthe keel line and which is located not less than a vertical distance h measured from the keel line, as calculated by theformula:h = B/20
However, in no case is the value of h to be less than 760 mm, and need not be taken as more than 2,000 mm.
Where the height of the double bottom varies, the variation is generally to be made gradually and over an adequate
length; the knuckles of inner bottom plating are to be located in way of plate floors.
Where this is impossible, suitable longitudinal structures such as partial girders, longitudinal brackets etc., fitted
across the knuckle are to be arranged.
6.1.4 Dimensions of double bottom
The breadth of double bottom is taken as shown in Fig. 17
Fig. 17

Breadth of double bottom－68－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

6.1.5 Docking
The bottom is to have sufficient strength to withstand the loads resulting from the dry-docking of the ship.
Where docking brackets are provided between solid floors and connecting the centreline girder to the bottom shell
plating, the docking brackets are to be connected to the adjacent bottom longitudinals.
6.1.6 Continuity of strength
Where the framing system changes from longitudinal to transverse, special attention is to be paid to the continuityof strength by means of additional girders or floors. Where this variation occurs within 0.6LCSR-B amidships, the inner
bottom is generally to be maintained continuous by means of inclined plating.
Bottom and inner bottom longitudinal ordinary stiffeners are generally to be continuous through the floors.
The actual net thickness and the yield stress of the lower strake of the sloped bulkhead of hopper tanks, if any, are
not to be less than these ones of the inner bottom with which the connection is made.
6.1.7 Reinforcement
The bottom is to be locally stiffened where concentrated loads are envisaged such as under the main engine andthrust seat.
Girders and floors are to be fitted under each line of pillars, toes of end brackets of bulkhead stiffeners and slant
plate of lower stool of bulkhead. In case girders and floors are not fitted, suitable reinforcement is to be provided bymeans of additional primary supporting members or supporting brackets.
When solid ballast is fitted, it is to be securely positioned. If necessary, intermediate floors may be required for thispurpose.
6.1.8 Manholes and lightening holes
Manholes and lightening holes are to be provided in floors and girders to ensure accessibility and ventilation as arule.
The number of manholes in tank tops is to be kept to the minimum compatible with securing free ventilation andready access to all parts of the double bottom.
Manholes may not be cut in the girders and floors below the heels of pillars.
6.1.9 Air holes and drain holes
Air and drain holes are to be provided in floors and girders.
Air holes are to be cut as near to the inner bottom and draining holes as near to the bottom shell as practicable.
Air holes and drain holes are to be designed to aid full ballast water and sediment removal to allow for effective
ballast water exchange.
6.1.10 Drainage of tank top
Effective arrangements are to be provided for draining water from the tank top. Where wells are provided for thedrainage, such wells are not to extend for more than one-half depth of the height of double bottom
6.1.11 Striking plate
Striking plates of adequate thickness or other equivalent arrangements are to be provided under sounding pipes toprevent the sounding rod from damaging the bottom plating.
6.1.12 Duct keel
Where a duct keel is arranged, the centre girder may be replaced by two girders generally spaced, no more than
3 m apart.
The structures in way of the floors are to ensure sufficient continuity of the latter.
6.2
Keel
6.2.1
The width of the keel is to be not less than the value obtained, in m, from the following formula:b = 0.8 + LCSR-B/200
6.3
Girders
6.3.1 Centre girder
The centre girder is to extend within the cargo hold area and is to extend forward and aft as far as practicable, andstructural continuity thereof to be continuous within the full length of the ship.
Where double bottom compartments are used for the carriage of fuel oil, fresh water or ballast water, the centre
girder is to be watertight, except for the case such as narrow tanks at the end parts or when other watertight girders
are provided within 0.25B from the centreline, etc.
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6.3.2 Side girders
The side girders are to extend within the parallel part of cargo hold area and are to extend forward and aft of cargohold area as far as practicable.
6.3.3 Spacing
The spacing of adjacent girders is generally to be not greater than 4.6 m or 5 times the spacing of bottom or inner
bottom ordinary stiffeners, whichever is the smaller. Greater spacing may be accepted depending on the result of theanalysis carried out according to Ch 7.
6.4
Floors
6.4.1 Spacing
The spacing of floors is generally to be not greater than 3.5 m or 4 frame spaces as specified by the designer,
whichever is the smaller. Greater spacing may be accepted depending on the result of the analysis carried out
according to Ch 7.
6.4.2 Floors in way of transverse bulkheads
Where transverse bulkhead is provided with lower stool, solid floors are to be fitted in line with both sides of lower
stool. Where transverse bulkhead is not provided with lower stool, solid floors are to be fitted in line with bothflanges of the vertically corrugated transverse bulkhead or in line of plane transverse bulkhead.
6.4.3 Web stiffeners
Floors are to be provided with web stiffeners in way of longitudinal ordinary stiffeners. Where the web stiffeners
are not provided, fatigue strength assessment for the cut out and connection of longitudinal stiffener is to be carriedout.
6.5
Bilge strake and bilge keel
6.5.1 Bilge strake
Where some of the longitudinal stiffeners at the bilge part are omitted, longitudinal stiffeners are to be provided asnear to the turns of bilge as practicable.
6.5.2 Bilge keel
Bilge keels are not be welded directly to the shell plating. An intermediate flat is required on the shell plating. The
ends of the bilge keel are to be sniped as shown in Fig.18 or rounded with large radius. The ends are to be located in
way of transverse bilge stiffeners inside the shell plating and the ends of intermediate flat are not to be located at theblock joints.
The bilge keel and the intermediate flat are to be made of steel with the same yield stress as the one of the bilge
strake. The bilge keel with a length greater than 0.15LCSR-B is to be made with the same grade of steel as the one ofbilge strake.
The net thickness of the intermediate flat is to be equal to that of the bilge strake. However, this thickness may
generally not be greater than 15 mm.
Scallops in the bilge keels are to be avoided.

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Fig. 18

Example of bilge keel arrangementthabout 3hmin. 100

about 1.5b7.

br ³ 2tDouble Side structure in cargo hold area

7.1
Application
7.1.1
The requirement of this article applies to longitudinally or transversely framed side structure.
The transversely framed side structures are built with transverse frames possibly supported by horizontal side
girders.
The longitudinally framed side structures are built with longitudinal ordinary stiffeners supported by verticalprimary supporting members.
The side within the hopper and topside tanks is, in general, to be longitudinally framed. It may be transversely
framed when this is accepted for the double bottom and the deck according to 6.1.2 and 9.1.1, respectively.
7.2
Design principles
7.2.1
Where the double side space is void, the structural members bounding this space are to be structurally designed asa water ballast tank according to Ch 6. In such case the corresponding air pipe is considered as extending 0.76 m
above the freeboard deck at side.
For corrosion addition, the space is still considered as void space.
7.3
Structural arrangement
7.3.1 General
Double side structures are to be thoroughly stiffened by providing web frames and side stringers within the doublehull.
Continuity of the inner side structures, including stringers, is to be ensured within and beyond the cargo area.
Scarfing brackets are a possible means.
7.3.2 Primary supporting member spacing
For transverse framing system, the spacing of transverse side primary supporting members is, in general, to be notgreater than 3 frame spaces.
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Greater spacing may be accepted depending on the results of the analysis carried out according to Ch 7 for the
primary supporting members in the cargo holds.
The vertical distance between horizontal primary members of the double side is not to exceed 6 m, unless theappropriate structural members complying with the requirements for safe access are provided.
7.3.3 Primary supporting member fitting
Transverse side primary supporting members are to be fitted in line with web frames in topside and hopper tanks.
However where it is not practicable for top side web frames, large brackets are to be fitted in the topside space in linewith double side web frames
Transverse bulkheads in double side space are to be arranged in line with the cargo hold transverse bulkheads.
Vertical primary supporting members are to be fitted in way of hatch end beams.
Unless otherwise specified, horizontal side girders are to be fitted aft of the collision bulkhead up to 0.2LCSR-B aft of
the fore end, in line with fore peak girders.
7.3.4 Transverse ordinary stiffeners
The transverse ordinary stiffeners of the shell and the inner side are to be continuous or fitted with bracket end
connections within the height of the double side. The transverse ordinary stiffeners are to be effectively connected tostringers. At their upper and lower ends, opposing shell and inner side transverse ordinary stiffeners and supporting
stringer plates are to be connected by brackets.
7.3.5 Longitudinal ordinary stiffeners
The longitudinal side shell and inner side ordinary stiffeners, where fitted, are to be continuous within the length ofthe parallel part of cargo hold area and are to be fitted with brackets in way of transverse bulkheads aligned withcargo hold bulkheads. They are to be effectively connected to transverse web frames of the double side structure. For
the side longitudinal and ordinary stiffeners of inner skin out of parallel part of cargo hold area, special attention is tobe paid for a structural continuity.
7.3.6 Sheer strake
The width of the sheer strake is to be not less than the value obtained, in m, from the following formula:b = 0.715 + 0.425LCSR-B / 100
The sheer strake may be either welded to the stringer plate or rounded.
If the shear strake is rounded, its radius, in mm, is to be not less than 17ts, where ts is the net thickness, in mm, ofthe sheer strake.
The fillet weld at the connection of the welded sheer strake and deck plate may be either full penetration or deep
penetration weld.
The upper edge of the welded sheer strake is to be rounded smooth and free of notches. Fixtures such as bulwarks,
eye plates are not to be directly welded on the upper edge of sheer strake, except in fore and aft parts.
Longitudinal seam welds of rounded sheer strake are to be located outside the bent area at a distance not less than 5times the maximum net thicknesses of the sheer strake.
The transition from a rounded sheer strake to an angled sheer strake associated with the arrangement ofsuperstructures at the ends of the ship is to be carefully designed so as to avoid any discontinuities.
7.3.7 Plating connection
At the locations where the inner hull plating and the inner bottom plating are connected, attention is to be paid tothe structural arrangement so as not to cause stress concentration.
Knuckles of the inner side are to be adequately stiffened by ordinary stiffeners or equivalent means, fitted in linewith the knuckle.
The connections of hopper tank plating with inner hull and with inner bottom are to be supported by a primary
supporting member.
7.4
Longitudinally framed double side
7.4.1 General
Adequate continuity of strength is to be ensured in way of breaks or changes in the width of the double side.
7.5
Transversely framed double side
7.5.1 General
Transverse frames of side and inner side may be connected by means of struts. Struts are generally to be connected
to transverse frames by means of vertical brackets.
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8.

Single side structure in cargo hold area

8.1
Application
8.1.1
This article applies to the single side structure with transverse framing.
If single side structure is supported by transverse or longitudinal primary supporting members, the requirements in
7 above apply to these primary supporting members as regarded to ones in double side skin.
8.2
General arrangement
8.2.1
Side frames are to be arranged at every frame space.
If air pipes are passing through the cargo hold, they are to be protected by appropriate measures to avoid amechanical damage.
8.3
Side frames
8.3.1 General
Frames are to be built-up symmetrical sections with integral upper and lower brackets and are to be arranged with
soft toes.
The side frame flange is to be curved (not knuckled) at the connection with the end brackets. The radius ofcurvature is not to be less than r, in mm, given by:r=

0.4b 2ft f + tC

where:: Corrosion addition, in mm, specified in Ch 3, Sec 3tC
bf and tf : Flange width and net thickness of the curved flange, in mm. The end of the flange is to be sniped.
In ships less than 190 m in length, mild steel frames may be asymmetric and fitted with separate brackets. The faceplate or flange of the bracket is to be sniped at both ends. Brackets are to be arranged with soft toes.
The dimensions of side frames are defined in Fig. 19.
8.4
Upper and lower brackets
8.4.1
The face plates or flange of the brackets is to be sniped at both ends.
Brackets are to be arranged with soft toes.
The as-built thickness of the brackets is to be not less than the as-built thickness of the side frame webs to which
they are connected.
8.4.2
The dimensions (in particular the height and length) of the lower brackets and upper brackets are to be not less thanthose shown in Fig. 20.

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Fig. 19

Fig. 20

Dimensions of side frames

Dimensions of lower and upper brackets－74－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

8.5
Tripping brackets
8.5.1
In way of the foremost hold and in the holds of BC-A ships, side frames of asymmetrical section are to be fittedwith tripping brackets at every two frames, as shown in Fig. 21.
The as-built thickness of the tripping brackets is to be not less than the as-built thickness of the side frame webs towhich they are connected.
Double continuous welding is to be adopted for the connections of tripping brackets with side shell frames andplating.
Fig. 21

Tripping brackets to be fitted in way of foremost hold

8.6
Support structure
8.6.1
Structural continuity with the lower and upper end connections of side frames is to be ensured within hopper andtopside tanks by connecting brackets as shown in Fig. 22. The brackets are to be stiffened against buckling according
to 5.6.2.

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Fig. 22

9.

Example of support structure for lower end

Deck structure

9.1
Application
9.1.1
The deck outside the line of hatches and the topside tank sloping plates are to be longitudinally framed. Within theline of hatches, other arrangement than longitudinal framing may be considered provided that adequate structuralcontinuity is ensured.
9.2
General arrangement
9.2.1
The spacing of web frames in topside tanks is generally to be not greater than 6 frame spaces.
Greater spacing may be accepted by the Society, on a case-by-case basis, depending on the results of the analysis
carried out according to Ch 7.
9.2.2
The deck supporting structure is to be made of ordinary stiffeners longitudinally or transversely arranged,
supported by primary supporting members.
9.2.3 Deck between hatches
Inside the line of openings, a transversely framed structure is to be generally adopted for the cross deck structures.
Hatch end beams and cross deck beams are to be adequately supported by girders and extended outward to the second
longitudinal from the hatch side girders towards the deck side. Where this is impracticable, intercostal stiffeners areto be fitted between the hatch side girder and the second longitudinal. If the extension of beams outward to thesecond longitudinal is not achievable, structural checks of the structure are to be performed in compliance with therequirements in Ch 7 or by means deemed appropriate by the Society.
Smooth connection of the strength deck at side with the deck between hatches is to be ensured by a plate ofintermediate thickness.
9.2.4 Topside tank structures
Topside tank structures are to extend as far as possible within the machinery space and are to be adequately
tapered.
Where a double side primary supporting member is fitted outside the plane of the topside tank web frame, a large
bracket is to be fitted in line with.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

9.2.5 Stringer plate
The width of the stringer plate is to be not less than the value obtained, in m, from the following formula:b = 0.35 + 0.5LCSR-B / 100
Rounded stringer plate, where adopted, are to have a radius complying with the requirements in 7.3.6.
9.2.6
Adequate continuity of strength by providing proper overlapping of structures and adequate scarphing members is
to be ensured in way of:・ stepped strength deck・ changes in the framing system
9.2.7
Deck supporting structures under deck machinery, cranes, king post and equipment such as towing equipment,
mooring equipment, etc., are to be adequately stiffened.
9.2.8
Pillars or other supporting structures are to be generally fitted under heavy concentrated loads.
9.2.9
A suitable stiffening arrangement is considered in way of the ends and corners of deckhouses and partial
superstructures.
9.2.10 Connection of hatch end beams with deck structures
The connection of hatch end beams with deck structures is to be properly ensured by fitting inside the topside tanks
additional web frames or brackets.
9.2.11 Construction of deck plating
Hatchways or other openings on decks are to have rounded corners, and compensation is to be suitably provided.
9.3
Longitudinally framed deck
9.3.1 General
Deck longitudinals within the parallel part of cargo hold area except within the line of hatch openings are to becontinuous in way of deck transverses and transverse bulkheads. For the deck longitudinals out of parallel part ofcargo hold area, other arrangements may be considered, provided adequate continuity of longitudinal strength isensured.
Connections at ends of longitudinal stiffeners are to ensure a sufficient strength to bending and shear.
9.4
Transversely framed deck
9.4.1 General
Where the deck structure is transversely framed, deck beams or deck transverse stiffeners are to be fitted at eachframe.
Transverse beams or deck transverse stiffeners are to be connected to side structure or frames by brackets.
9.5
Hatch supporting structures
9.5.1
Hatch side girders and hatch end beams of reinforced scantlings are to be fitted in way of cargo hold openings.
9.5.2
The connection of hatch end beams to web frames is to be ensured. Hatch end beams are to be aligned withtransverse web frames in topside tanks.
9.5.3
Clear of openings, adequate continuity of strength of longitudinal hatch coamings is to be ensured by underdeck
girders.
At hatchway corners, deck girders or their extension parts provided under deck in line with hatch coamings andhatch end beams are to be effectively connected so as to maintain the continuity in strength.
9.5.4
For ships with holds designed for loading/discharging by grabs and having the additional class notation GRAB[X],wire rope grooving in way of cargo holds openings is to be prevented by fitting suitable protection such as half-roundbar on the hatch side girders (i.e. upper portion of top side tank plates)/hatch end beams in cargo hold and upper
portion of hatch coamings.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

9.6
Openings in the strength deck
9.6.1 General
Openings in the strength deck are to be kept to a minimum and spaced as far as practicable from one another andfrom the breaks of effective superstructures. Openings are to be cut as far as practicable from hatchway corners,
hatch side coamings and side shell platings.
9.6.2 Small opening location
Openings are generally to be cut outside the limits as shown in Fig. 23 in dashed area, defined by:・ the bent area of a rounded sheer strake, if any, or the side shell・ e = 0.25(B - b) from the edge of opening
・ c = 0.07l + 0.1b or 0.25b, whichever is greater
where:
b : Width, in m, of the hatchway considered, measured in the transverse direction. (see Fig. 23)
l : Width, in m, in way of the corner considered, of the cross deck strip between two consecutive
hatchways, measured in the longitudinal direction. (see Fig. 23).
Moreover the transverse distance between these limits and openings or between openings together is not to be lessthan the followings:
・ Transverse distance between the above limits and openings or between hatchways and openings as shownin Fig. 23:
for circular openings
・ g 2 = 2a2
・ g1 = a1
for elliptical openings
・ Transverse distance between openings as shown in Fig. 24:
・ 2(a1 + a2 )for circular openings
for elliptical openings
・ 1.5(a1 + a2 )where
a1 : Transverse dimension of elliptical openings, or diameter of circular openings, as the case may be
a2 : Transverse dimension of elliptical openings, or diameter of circular openings, as the case may be
a3 : Longitudinal dimension of elliptical openings, or diameter of circular openings, as the case may be・ Longitudinal distance between openings is not to be less than the followings:
for circular openings
・ (a1 + a3 )for elliptical openings and for an elliptical opening in line with a circular one.
・ 0.75(a1 + a3 )If the opening arrangements do not comply with these requirements, the longitudinal strength assessment inaccordance with Ch 5 is to be carried out by subtracting such opening areas.
Fig. 23

Position of openings in strength deck－78－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

Fig. 24

Elliptical and circular openings in strength decka2

a2

³ 1.5(a1 + a 2 )³ 2(a1 + a 2 )a1

a1³ 0.75(a1 + a3 )

a3

³ (a1 + a3 )a3

9.6.3 Corner of hatchways
For hatchways located within the cargo area, insert plates, whose thickness is to be determined according to theformula given after, are generally to be fitted in way of corners where the plating cut-out has a circular profile.
The radius of circular corners is to be not less than 5% of the hatch width, where a continuous longitudinal deck
girder is fitted below the hatch coaming.
Corner radius, in the case of the arrangement of two or more hatchways athwartship, is considered by the Society
on a case by case basis.
For hatchways located within the cargo area, insert plates are, in general, not required in way of corners where theplating cut-out has an elliptical or parabolic profile and the half axes of elliptical openings, or the half lengths of theparabolic arch, are not less than:・ 1/20 of the hatchway width or 600 mm, whichever is the lesser, in the transverse direction
・ twice the transverse dimension, in the fore and aft direction.
Where insert plates are required, their net thickness is to be obtained, in mm, from the following formula:t INS = (0.8 + 0.4b / l ) t
without being taken less than t or greater than 1.6t
where:
l : Width, in m, in way of the corner considered, of the cross deck strip between two consecutive
hatchways, measured in the longitudinal direction (see Fig. 23)
b : Width, in m, of the hatchway considered, measured in the transverse direction (see Fig. 23)
t : Actual net thickness, in mm, of the deck at the side of the hatchways.
For the extreme corners of end hatchways, the thickness of insert plates is to be 60% greater than the actual
thickness of the adjacent deck plating. A lower thickness may be accepted by the Society on the basis of calculations
showing that stresses at hatch corners are lower than permissible values.
Where insert plates are required, the arrangement is shown in Fig. 25, in which d1, d2, d3 and d4 are to be greaterthan the ordinary stiffener spacing.
For hatchways located outside the cargo area, a reduction in the thickness of the insert plates in way of corners
may be considered by the Society on a case by case basis.
For ships having length LCSR-B of 150 m or above, the corner radius, the thickness and the extent of insert plate may
be determined by the results of a direct strength assessment according to Ch 7, Sec 2 and Sec 3, including bucklingcheck and fatigue strength assessment of hatch corners according to Ch 8, Sec 5.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

Fig. 25

10.

Hatch corner insert plate

Bulkhead structure

10.1
Application
10.1.1
The requirements of this article apply to longitudinal and transverse bulkhead structures which may be plane or
corrugated.
10.1.2 Plane bulkheads
Plane bulkheads may be horizontally or vertically stiffened.
Horizontally framed bulkheads are made of horizontal ordinary stiffeners supported by vertical primary supporting
members.
Vertically framed bulkheads are made of vertical ordinary stiffeners which may be supported by horizontal girders.
10.2
General10.2.1
The web height of vertical primary supporting members of bulkheads may be gradually tapered from bottom todeck.
10.2.2The net thickness of the after peak bulkhead plating in way of the stern tube is to be increased by at least 60% ofother part of after peak bulkhead plating
10.3
Plane bulkheads
10.3.1 General
Where a bulkhead does not extend up to the uppermost continuous deck, suitable strengthening is to be provided in
the extension of the bulkhead.
Bulkheads are to be stiffened in way of the deck girders.
The bulkhead stiffener webs of hopper and topside tank watertight bulkheads are required to be aligned with thewebs of longitudinal stiffeners of sloping plates of inner hull.
A primary supporting member is to be provided in way of any vertical knuckle in longitudinal bulkheads. The
distance between the knuckle and the primary supporting member is to be taken not greater than 70 mm. When the
knuckle is not vertical, it is to be adequately stiffened by ordinary stiffeners or equivalent means, fitted in line withthe knuckle.
Plate floors are to be fitted in the double bottom in line with the plate transverse bulkhead.
10.3.2 End connection of ordinary stiffeners
The crossing of ordinary stiffeners through a watertight bulkhead is to be watertight.
In general, end connections of ordinary stiffeners are to be bracketed. If bracketed end connections cannot beapplied due to hull lines, etc., they are to be terminated on transverse headers between adjacent longitudinal or if notpossible, sniped ends may be accepted, provided the scantling of ordinary stiffeners and corresponding plating are
modified accordingly.
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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

10.3.3 Sniped end of ordinary stiffener
Sniped ends are not allowed on bulkheads subject to hydrostatic pressure. Where sniped ordinary stiffeners are
fitted, the snipe angle is not to be greater than 30 degrees, and their ends are to be extended as far as practicable tothe boundary of the bulkhead.
10.3.4 Bracketed ordinary stiffeners
Where bracketed ordinary stiffeners are fitted, the arm lengths of end brackets of ordinary stiffeners, as shown in
Figs. 26 and 27, are to be not less than the following values, in mm:
・ for arm length a:・ brackets of horizontal stiffeners and bottom bracket of vertical stiffeners:
a = 100l
・ upper bracket of vertical stiffeners:
a = 80l
・ for arm length b, the greater ofb = 80{( w + 20) / t}0.5 andb = apsl / twhere:
l : Span, in m, of the stiffener measured between supports
w : Net section modulus, in cm3, of the stiffenert : Net thickness, in mm, of the bracket
p : Design pressure, in kN/m2, calculated at mid-span
a : Coefficient equal to:a = 4.9
for tank bulkheads
a = 3.6
for watertight bulkheads.
The connection between the stiffener and the bracket is to be such that the net section modulus of the connection is
not less than that of the stiffener.
Fig. 26

Bracket at upper end of ordinary stiffener on plane bulkhead

Fig. 27

Bracket at lower end of ordinary stiffener on plane bulkhead－81－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

10.4
Corrugated bulkheads
10.4.1 General
For ships of 190m of length LCSR-B and above, the transverse vertically corrugated watertight bulkheads are to be
fitted with a lower stool and generally with an upper stool below deck. For ships less than 190m in length LCSR-B,
corrugations may extend from inner bottom to deck provided the global strength of hull structures are satisfactorily
proved for ships having ship length LCSR-B of 150m and above by DSA as required by Ch 7.
10.4.2 Construction
The main dimensions a, R, c, d, t, j and sC of corrugated bulkheads are defined in Fig. 28.
The bending radius is not to be less than the following values, in mm:
R = 3.0t
where:
t : As-built thickness, in mm, of the corrugated plate.
The corrugation angle j shown in Fig. 28 is to be not less than 55 .
When welds in a direction parallel to the bend axis are provided in the zone of the bend, the welding procedures
are to be submitted to the Society for approval.
Fig. 28

Dimensions of a corrugated bulkhead
a
c

tf
R

tw

j ³ 55 odsC

10.4.3 Actual section modulus of corrugations
The net section modulus of a corrugation may be obtained, in cm3, from the following formula:é d (3at f + ctw ) ù - 3
w=ê
ú 10
6
ë
û
where:
tf, tw : Net thickness of the plating of the corrugation, in mm, shown in Fig. 28
d, a, c : Dimensions of the corrugation, in mm, shown in Fig. 28.
Where the web continuity is not ensured at ends of the bulkhead, the net section modulus of a corrugation is to beobtained, in cm3, from the following formula:w = 0.5 a t f d 10-3
10.4.4 Span of corrugations
The span lC of the corrugations is to be taken as the distance shown in Fig. 29.
For the definition of lC, the internal end of the upper stool is not to be taken more than a distance from the deck at
the centre line equal to:- 3 times the depth of corrugation, in general- 2 times the depth of corrugation, for rectangular stool－82－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

Fig. 29

Span of the corrugations

10.4.5 Structural arrangements
The strength continuity of corrugated bulkheads is to be ensured at the ends of corrugations.
Where corrugated bulkheads are cut in way of primary supporting members, attention is to be paid to ensure
correct alignment of corrugations on each side of the primary member.
Where vertically corrugated transverse bulkheads or longitudinal bulkheads are welded on the inner bottom plate,floors or girders are to be fitted in way of flanges of corrugations, respectively.
In general, the first vertical corrugation connected to the boundary structures is to have a width not smaller thantypical width of corrugation flange.
10.4.6 Bulkhead stools
Plate diaphragms or web frames are to be fitted in bottom stools in way of the double bottom longitudinal girders
or plate floors, as the case may be.
Brackets or deep webs are to be fitted to connect the upper stool to the deck transverse or hatch end beams, as thecase may be.
10.4.7 Lower stool
The lower stool, when fitted, is to have a height in general not less than 3 times the depth of the corrugations.
The ends of stool side ordinary stiffeners, when fitted in a vertical plane, are to be attached to brackets at the upperand lower ends of the stool.
The distance d from the edge of the stool top plate to the surface of the corrugation flange is to be in accordancewith Fig. 30.
The stool bottom is to be installed in line with double bottom floors or girders as the case may be, and is to have awidth not less than 2.5 times the mean depth of the corrugation.
The stool is to be fitted with diaphragms in line with the longitudinal double bottom girders or floors as the casemay be, for effective support of the corrugated bulkhead. Scallops in the brackets and diaphragms in way of theconnections to the stool top plate are to be avoided.
Where corrugations are cut at the lower stool, corrugated bulkhead plating is to be connected to the stool top plateby full penetration welds. The stool side plating is to be connected to the stool top plate and the inner bottom plating－83－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

by either full penetration or deep penetration welds. The supporting floors are to be connected to the inner bottom byeither full penetration or deep penetration weld.
Fig. 30

Permitted distance, d, from the edge of the stool top plate to the surface of the corrugation flange

10.4.8 Upper stool
The upper stool, when fitted, is to have a height in general between two and three times the depth of corrugations.
Rectangular stools are to have a height in general equal to twice the depth of corrugations, measured from the deck
level and at the hatch side girder.
The upper stool of transverse bulkhead is to be properly supported by deck girders or deep brackets between theadjacent hatch end beams.
The width of the upper stool bottom plate is generally to be the same as that of the lower stool top plate. The stool
top of non-rectangular stools is to have a width not less than twice the depth of corrugations.
The ends of stool side ordinary stiffeners when fitted in a vertical plane, are to be attached to brackets at the upperand lower end of the stool.
The stool is to be fitted with diaphragms in line with and effectively attached to longitudinal deck girders
extending to the hatch end coaming girders or transverse deck primary supporting members as the case may be, foreffective support of the corrugated bulkhead.
Scallops in the brackets and diaphragms in way of the connection to the stool bottom plate are to be avoided.
10.4.9 Alignment
At deck, if no upper stool is fitted, two transverse or longitudinal reinforced beams as the case may be, are to be
fitted in line with the corrugation flanges.
At bottom, if no lower stool is fitted, the corrugation flanges are to be in line with the supporting floors or girders.
The weld of corrugations and floors or girders to the inner bottom plating are to be full penetration ones. The
cut-outs for connections of the inner bottom longitudinals to double bottom floors are to be closed by collar plates.
The supporting floors or girders are to be connected to each other by suitably designed shear plates.
Stool side plating is to be aligned with the corrugation flanges. Lower stool side vertical stiffeners and theirbrackets in the stool are to be aligned with the inner bottom structures as longitudinals or similar, to provide
appropriate load transmission between these stiffening members.
Lower stool side plating is not to be knuckled anywhere between the inner bottom plating and the stool top plate.
10.4.10 Effective width of the compression flange
The effective width of the corrugation flange in compression to be considered for the strength check of thebulkhead is to be obtained, in m, from the following formula:
bef = C E awhere:
CE : Coefficient to be taken equal to:
2.25 1.25
CE =- 2
for b > 1.25bb
CE = 1.0
for b £ 1.25

－84－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6): Coefficient to be taken equal to:b = 103

a
tf

ReH
E

a : Width, in m, of the corrugation flange (see Fig. 28)
tf : Net flange thickness, in mm.
10.4.11 Effective shedder plates
Effective shedder plates are those which:・ are not knuckled
・ are welded to the corrugations and the lower stool top plate according to Ch 11
・ are fitted with a minimum slope of 45 , their lower edge being in line with the lower stool side plating・ have thickness not less than 75% of that required for the corrugation flanges
・ have material properties not less than those required for the flanges.
10.4.12 Effective gusset plates
Effective gusset plates are those which:・ are in combination with shedder plates having thickness, material properties and welded connections asrequested for shedder plates in 10.4.11,
・ have a height not less than half of the flange width,
・ are fitted in line with the lower stool side plating,・ are welded to the lower stool top plate, corrugations and shedder plates according to Ch 11,Sec2.
・ have thickness and material properties not less than those required for the flanges.
10.4.13 (void)
Fig. 31(void)

Fig. 32(void)

Fig. 33(void)

Fig. 34(void)

Fig. 35(void)

10.4.14 (void)10.4.15 (void)
10.5
Non-tight bulkheads
10.5.1 Non-tight bulkheads not acting as pillars
Non-tight bulkheads not acting as pillars are to be provided with bulkhead stiffeners with a maximum spacing
equal to:・ 0.9 m, for transverse bulkheads
・ two frame spacings, with a maximum of 1.5 m, for longitudinal bulkheads.
The net thickness of bulkhead stiffener, in mm, is not to be less than the value obtained from the following
formula:t = 3 + 0.015L2
where:
L2 : Rule length LCSR-B, but to be taken not greater than 300 m
The depth of bulkhead stiffener of flat bar type is in general not to be less than 1/12 of stiffener length. A smaller
depth of stiffener may be accepted based on calculations showing compliance with Ch 6, Sec 2, 2.3.1, Ch 6, Sec 2, 4
and Ch 6, Sec 3, 4.
10.5.2 Non-tight bulkheads acting as pillars
Non-tight bulkheads acting as pillars are to be provided with bulkhead stiffeners with a maximum spacing equal to:・ two frame spacings, when the frame spacing does not exceed 0.75 m,－85－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 3 Section 6)

・ one frame spacing, when the frame spacing is greater than 0.75 m.
Each vertical stiffener, in association with a width of plating equal to 35 times the plating net thickness or 1/12 ofstiffener length, whichever is the smaller, is to comply with the applicable requirements in Ch 6, Sec 2, for the load
being supported.
In the case of non-tight bulkheads supporting longitudinally framed decks, vertical girders are to be provided in
way of deck transverse.
10.6
Watertight bulkheads of trunks and tunnels
10.6.1
Ref. SOLAS Ch. II-1, Part B, Reg. 19.1
Watertight trunks, tunnels, duct keels and ventilators are to be of the same strength as watertight bulkheads atcorresponding levels. The means used for making them watertight, and the arrangements adopted for closing
openings in them, are to be to the satisfaction of the Society.
11.

Pillars

11.1
General11.1.1
Pillars are to be fitted, as far as practicable, in the same vertical line. If not possible, effective means are to beprovided for transmitting their loads to the supports below.
11.1.2
Pillars are to be provided in line with the double bottom girder or as close thereto as practicable, and the structure
above and under the pillars is to be of sufficient strength to provide effective distribution of the load. Where pillars
connected to the inner bottom are not located in way of the intersection of floors and girders, partial floors or girders
or equivalent structures suitable to support the pillars are to be arranged.
11.1.3
Pillars provided in tanks are to be of solid or open section type. Pillars located in spaces intended for products
which may produce explosive gases are to be of open section type.
11.1.4 Connections
Heads and heels of pillars are to be secured by thick doubling plates and brackets as necessary. Where the pillars
are likely to be subjected to tensile loads such as those in tanks, the head and heel of pillars are to be efficiently
secured to withstand the tensile loads and the doubling plates replaced by insert plate.
In general, the net thickness of doubling plates is to be not less than 1.5 times the net thickness of the pillar.
Pillars are to be attached at their heads and heels by continuous welding.

－86－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 1)

Chapter 4
Section 1
1.

DESIGN LOADSGENERAL

General1.1
1.1.1
The equivalent design wave (EDW) method is used to set the design loads which include lateral loads normal toplating and hull girder loads in still water and in waves.
1.1.2
External hydrostatic pressure and internal static pressure due to cargo and ballast are considered as lateral loads instill water. External hydrodynamic pressure and internal inertial pressure due to cargo and ballast are considered aslateral loads in waves.
1.1.3
Still water vertical shear force and bending moment, wave-induced vertical shear force and bending moment andwave-induced horizontal bending moment are considered as the hull girder loads.
1.1.4
The stresses due to the lateral loads in waves and the hull girder loads in waves are to be combined using load
combination factors determined for each equivalent design wave.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 2)

Section 2

SHIP MOTIONS AND ACCELERATIONS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
a0 : Acceleration parameter, taken equal to:æ 2 .434600 ö
a0 = f p (1.58 - 0.47C B )ç+
ç L
LCSR- B LCSR- B 2
øè CSR-B
TR : Roll period, in s, defined in 2.1.1
q : Single roll amplitude, in deg, defined in 2.1.1
TP : Pitch period, in s, defined in 2.2.1
F : Single pitch amplitude, in deg, defined in 2.2.1
fp : Coefficient corresponding to the probability level, taken equal to:
fp = 1.0 for strength assessments corresponding to the probability level of 10-8
fp = 0.5 for strength assessments corresponding to the probability level of 10-4

1.

General1.1
1.1.1
Ship motions and accelerations are assumed to be periodic. The motion amplitudes, defined by the formulae in thisSection, are half of the crest to trough amplitudes.
1.1.2
As an alternative to the formulae in this Section, the Society may accept the values of ship motions andaccelerations derived from direct calculations or obtained from model tests, when justified on the basis of the ship s
characteristics and intended service. In general, the values of ship motions and accelerations to be determined arethose which can be reached with a probability level of 10-8 or 10-4. In any case, the model tests or the calculations,
including the assumed sea scatter diagrams and spectra, are to be submitted to the Society for approval.
2.

Ship absolute motions and accelerations

2.1
Roll
2.1.1
The roll period TR, in s, and the single roll amplitude q, in deg, are given by:
2.3k rTR =GM
9000(1.25 - 0.025TR ) f p kbq=
(B + 75)p
where:
kb : Coefficient taken equal to:
kb = 1.2 for ships without bilge keel
kb = 1.0 for ships with bilge keel
kr : Roll radius of gyration, in m, in the considered loading condition. When kr is not known, the values
indicated in Table 1 may be assumed.
GM : Metacentric height, in m, in the considered loading condition. When GM is not known, the values
indicated in Table 1 may be assumed.

－88－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 2)

Table 1

Values of kr and GM

Loading condition
Full load condition

Alternate or homogeneous loading
Steel coil loading

kr

GM

0.35B

0.12B

0.42B

0.24B

Normal ballast condition

0.45B

0.33B

Heavy ballast condition

0.40B

0.25B

2.2
Pitch
2.2.1
The pitch period TP, in s, and the single pitch amplitude F, in deg, are given by:
TP =
= fp

2pl
g
960
V
4
LCSR - B C B

where:
æ T ö
l = 0 .6çç1 + LC LCSR - B
TS ø
è

2.3
Heave
2.3.1
The vertical acceleration due to heave, in m/s2, is given by:aheave = a0 g
2.4
Sway
2.4.1
The transverse acceleration due to sway, in m/s2, is given by:asway = 0.3a0 g
2.5
Surge
2.5.1
The longitudinal acceleration due to surge, in m/s2, is given by:asurge = 0.2a0 g
3.

Ship relative accelerations

3.1
General
3.1.1
At any point, the accelerations in X, Y and Z directions are the acceleration components which result from the ship
absolute motions and accelerations defined in 2.1 to 2.5.
3.2
Accelerations
3.2.1
The reference values of the longitudinal, transverse and vertical accelerations at any point are obtained from thefollowing formulae:
・ In longitudinal direction:a X = C XG g sin F + C XS asurge + C XP a pitch x
・ In transverse direction:
aY = CYG g sin q + CYS asway + CYR aroll y・ In vertical direction:
aZ = C ZH aheave + CZR aroll z + C ZP a pitch z－89－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 2)

where:
CXG, CXS, CXP, CYG, CYS, CYR, CZH, CZR and CZP : Load combination factors defined in Ch 4, Sec 4, 2.2
apitch x : Longitudinal acceleration due to pitch, in m/s2
2

a pitch x = F

p æ 2p öçR
180 çè TP ø

aroll y : Transverse acceleration due to roll, in m/s22aroll y = qp æ 2p öçR
180 çè TR ø

aroll z : Vertical acceleration due to roll, in m/s22

p æ 2p öçaroll z = qy180 çè TR ø
apitch z : Vertical acceleration due to pitch, in m/s2
2

a pitch z =wherep æ 2p öç(x - 0.45LCSR- B )180 çè TP ø

(x - 0.45 LCSR- B ) is to be taken not less than 0.2LCSR-B

DöæD T
R = z - min ç + LC ,2 2øè4x, y, z : X, Y and Z co-ordinates, in m, of any point considered with respect to the reference co-ordinate
system defined in Ch 1, Sec 4－90－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 3)

Section 3

HULL GIRDER LOADS

Symbolsx
fp

1.

For symbols not defined in this Section, refer to Ch 1, Sec 4.
: X co-ordinate, in m, of the calculation point with respect to the reference co-ordinate system: Coefficient corresponding to the probability, defined in Ch 4, Sec 2.

General1.1
Sign conventions of bending moments and shear forces
1.1.1
Absolute values are to be taken for bending moments and shear forces introduced in this Section. The sign ofbending moments and shear forces is to be considered according to Sec 4, Table 3. The sign conventions of verticalbending moments, horizontal bending moments and shear forces at any ship transverse section are as shown in Fig. 1,
namely:・ the vertical bending moments MSW and MWV are positive when they induce tensile stresses in the strength deck(hogging bending moment) and are negative in the opposite case (sagging bending moment)・ the horizontal bending moment MWH is positive when it induces tensile stresses in the starboard and is negativein the opposite case.
・ the vertical shear force Q SW , QWV are positive in the case of downward resulting forces preceding and upward
resulting forces following the ship transverse section under consideration, and is negative in the opposite case.
Fig. 1Sign conventions for shear forces Q SW, QWV and bending moments MSW, MWV, MWH(+)

QSW,QWV
Aft

Fore

(+)

MSW ,MWV
Aft

Fore

(+)

MWH

2.

Still water loads

2.1
General
2.1.1
In general the vertical still water bending moment and the shear force of the individual loading condition is to be
applied. The shipbuilder has to submit for each of the loading condition defined in Ch 4, Sec 7 a longitudinal strength
calculation.
The values of still water vertical bending moment and shear force are to be treated as the upper limits with respect
to hull girder strength.
In general, the design cargo and ballast loading conditions, based on amount of bunker, fresh water and stores at
departure and arrival, are to be considered for the MSW and QSW calculations. Where the amount and disposition of
consumables at any intermediate stage of the voyage are considered more severe, calculations for such intermediate－91－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 3)

conditions are to be submitted in addition to those for departure and arrival conditions. Also, where any ballasting
and/or deballasting is intended during voyage, calculations of the intermediate condition just before and just after
ballasting and/or deballasting any ballast tank are to be submitted and where approved included in the loading manualfor guidance.
2.1.2 Partially filled ballast tanks in ballast loading conditions
Ballast loading conditions involving partially filled peak and/or other ballast tanks at departure, arrival or during
intermediate conditions are not permitted to be used as design conditions unless:・ design stress limits are satisfied for all filling levels between empty and full, and・ for BC-A and BC-B ships, longitudinal strength of hull girder in flooded condition according to Ch 5, Sec 1,
2.1.3 is complied with for all filling levels between empty and full.
To demonstrate compliance with all filling levels between empty and full, it will be acceptable if, in each condition
at departure, arrival, and where required by 2.1.1, any intermediate condition, the tanks intended to be partially filled
are assumed to be:・ empty・ full・ partially filled at intended level
Where multiple tanks are intended to be partially filled, all combinations of empty, full or partially filled at
intended level for those tanks are to be investigated.
2.1.3 Partially filled ballast tanks in cargo loading conditions
In cargo loading conditions, the requirement in 2.1.2 applies to the peak tanks only.
2.1.4 Sequential ballast water exchange
Requirements of 2.1.2 and 2.1.3 are not applicable to ballast water exchange using the sequential method.
2.2
Still water bending moment
2.2.1
The design still water bending moments MSW,H and MSW,S at any hull transverse section are the maximum still water
bending moments calculated, in hogging and sagging conditions, respectively, at that hull transverse section for theloading conditions, as defined in 2.1.1. Greater values may be considered if defined by the Designer.
2.2.2
If the design still water bending moments are not defined, at a preliminary design stage, at any hull transverse
section, the longitudinal distributions shown in Fig. 2 may be considered.
In Fig. 2, MSW is the design still water bending moment amidships, in hogging or sagging conditions, whose values
are to be taken not less than those obtained, in kN-m, from the following formulae:
・ hogging conditions:2
M SW , H = 175CLCSR - B B (C B + 0.7 )10 -3 - M WV , H
・ sagging conditions:2
M SW ,S = 175CLCSR- B B(C B + 0.7)10 -3 - M WV ,S
where MWV,H and MWV,S are the vertical wave bending moments, in kN-m, defined in 3.1.
Fig. 2Preliminary still water bending moment distribution
Still water bending moment

MSW
0.2MSW
0.0
AE

0.3

0.5

－92－

0.7

1.0
FE

x CSR-B
x/LL

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 3)

2.3
Still water shear force
2.3.1
The design still water shear force QSW at any hull transverse section is the maximum positive or negative shear
force calculated, at that hull transverse section, for the loading conditions, as defined in 2.1.1. Greater values may beconsidered if defined by the Designer.
2.4
Still water bending moment and still water shear force in flooded condition
2.4.1
The still water bending moments MSW,F, in hogging and sagging conditions, and the still water shear force QSW,F, inflooded condition are to be determined for the flooding scenario considering each cargo hold individually flooded up
to the equilibrium waterline.
This means that double side spaces may not be considered flooded, and the cargo holds may not be considered
completely flooded, but only up to the equilibrium waterline.
2.4.2
To calculate the weight of ingressed water, the following assumptions are to be made:a) The permeability of empty cargo spaces and volume left in loaded cargo spaces above any cargo is to be taken
as 0.95.
b) Appropriate permeabilities and bulk densities are to be used for any cargo carried. For iron ore, a minimum
permeability of 0.3 with a corresponding bulk density of 3.0 t/m3 is to be used. For cement, a minimum
permeability of 0.3 with a corresponding bulk density of 1.3 t/m3 is to be used. In this respect, permeability forsolid bulk cargo means the ratio of the floodable volume between the particles, granules or any larger pieces of
the cargo, to the gross volume of the bulk cargo.
For packed cargo conditions (such as steel mill products), the actual density of the cargo should be used with apermeability of zero.
2.4.3
To quantify the effects of ingressed water on the hull girder still water bending moments and still water shear
forces, specific calculations are to be carried out. The loading conditions on which the design of the ship has been
based are to be considered and, for each of them, the cargo holds are to be considered as being individually flooded
up to the equilibrium waterline. The still water bending moments and still water shear forces are therefore to be
calculated for any combination of considered loading conditions and flooded cargo holds.
3.

Wave loads

3.1
Vertical wave bending moments
3.1.1 Intact condition
The vertical wave bending moments in intact condition at any hull transverse section are obtained, in kN-m, fromthe following formulae:
・ hogging conditions:
2
M WV , H = 190 FM f p CLCSR- B BC B 10 -3
・ sagging conditions:
2
M WV , S = 110 FM f p CLCSR- B B (C B + 0.7)10 -3
where:
FM : Distribution factor defined in Table 1 (see also Fig. 3).

－93－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 3)

Table 1

Distribution factor FM

Hull transverse section location

Distribution factor FM

2 .5

0 £ x < 0.4 LCSR - B

x
LCSR- B

0.4 LCSR - B £ x £ 0.65LCSR - B

1.0

0.65LCSR - B < x £ LCSR - Bæx ö
2.86çç1 è LCSR -B ø

Fig. 3Distribution factor FM

FM
1.0

0.0
AE

0.4

0.65

1.0
FE

x CSR-B
x/L
L

3.1.2 Flooded condition
The vertical wave bending moments in flooded condition at any hull transverse section are obtained, in kN-m, fromthe following formula:
M WV , F = 0.8M WV
where MWV is defined in 3.1.1.
3.1.3 Harbour condition
The vertical wave bending moments in harbour condition at any hull transverse section are obtained, in kN-m, fromthe following formula:
M WV , P = 0.4M WV
where MWV is defined in 3.1.1.
3.2
Vertical wave shear force
3.2.1 Intact condition
The vertical wave shear force in intact condition at any hull transverse section is obtained, in kN, from thefollowing formula:
QWV = 30FQ fpCLCSR-BB(CB + 0.7)10-2
where:
FQ : Distribution factor defined in Table 2 for positive and negative shear forces (see also Fig. 4).

－94－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 3)

Table 2Distribution factor FQ

Hull transverse section

Distribution factor FQ

location

Positive wave shear forcex
4.6 A
LCSR - B

0 £ x < 0.2 LCSR- B

Negative wave shear forcex
4.6
LCSR - B

0.2 LCSR - B £ x £ 0.3LCSR - B

0.92A

0.92

0.3LCSR- B < x < 0.4LCSR- Bæx ö(9.2 A - 7)çç 0.4 + 0.7
L
CSR -B øèæx ö
2.2çç 0.4 + 0. 7
LCSR -B øè

0.4 LCSR - B £ x £ 0.6 LCSR - B

0.7

0.7

0.6 LCSR- B < x < 0.7 LCSR - B

ö
æ x
3çç
- 0.6 + 0.7
Løè CSR -Böæ x
(10 A - 7)çç- 0.6 + 0.7
Løè CSR-B

0.7 LCSR - B £ x £ 0.85 LCSR - B

1

A

0.85LCSR - B < x £ LCSR - Bæx ö
6.67çç1 LCSR -B øèæx ö
6.67 Açç1 LCSR -B øè

Note : A =190C B
110(C B + 0.7 )Fig. 4FQ

Distribution factor FQ
FQ

for negative wave shear force

190 CB
110 (CB+0.7)
0.7

0.0

AE

for positive wave shear force

1.0

0.92
0.92

0.2 0.3 0.4

0.6 0.70.85

1.0

190 CB
110 (CB+0.7)
0.7

x CSR-B
x/L
L

FE

0.0

AE

－95－

0.2 0.3 0.4

0.6 0.7

0.85

1.0

FE

x CSR-B
x/LL

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 3)

3.2.2 Flooded condition
The vertical wave shear force in flooded condition at any hull transverse section are obtained, in kN, from thefollowing formula:
QWV , F = 0.8QWV
where QWV is defined in 3.2.1.
3.2.3 Harbour condition
The vertical wave shear force in harbour condition at any hull transverse section are obtained, in kN, from thefollowing formula:
QWV , P = 0.4QWV
where QWV is defined in 3.2.1.
3.3
Horizontal wave bending moment
3.3.1
The horizontal wave bending moment at any hull transverse section, in kN-m, is given by:Læö2
M WH = ç 0.3 + CSR - B FM f bCLCSR - B TLC C B
2000 ø
èwhere FM is the distribution factor defined in 3.1.1.
3.4
Wave torsional moment
3.4.1
The wave torsional moment at any hull transverse section, in kN-m, is given by:
M WT = f p ( M WT 1 + M WT 2 )where:LCSR- B 2
B DC B FT 1
T
M WT 2 = 0.22CLCSR - B B 2 C B FT 2

M WT 1 = 0.4C

FT1, FT2 : Distribution factors, defined as follows:æ 2px öFT 1 = sin çç
è LCSR-B øæ px ö
FT 2 = sin 2 çç
è LCSR - B ø－96－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 4)

Section 4

LOAD CASES

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
asurge, apitch x, asway, aroll y, aheave, aroll z, apitch z : Components of accelerations, defined in Ch 4, Sec 2.

1.

General1.1
Application
1.1.1
The load cases described in this section are those to be used for:・ the local strength analysis of plating and ordinary stiffeners and primary supporting members according to theapplicable requirements of Ch 6, Sec 1, Ch 6, Sec 2 and Ch 6, Sec 4 respectively,
・ the direct strength analysis of structural members, according to the applicable requirements of Ch 7,・ the fatigue check of structural details, according to the applicable requirements of Ch 8.
1.1.2
For the local strength analysis and for the direct strength analysis, the load cases are the mutually exclusive loadcases H1, H2, F1, F2, R1, R2, P1 and P2 described in 2.
1.2
Equivalent design wave
1.2.1
Regular waves that generate response values equivalent to the long-term response values of the load components
considered being predominant to the structural members are set as Equivalent Design Waves (EDWs). They consistof:・ regular waves when the vertical wave bending moment becomes maximum in head sea (EDW H )・ regular waves when the vertical wave bending moment becomes maximum in following sea (EDW F )・ regular waves when the roll motion becomes maximum (EDW R )・ regular waves when the hydrodynamic pressure at the waterline becomes maximum (EDW P )The definitions of wave crest and wave trough in the EDW H and EDW F are given in Fig. 1. The definitionsof weather side down and weather side up for the EDW R and EDW P are given in Fig. 2.
Fig. 1

Definition of wave crest and wave trough for EDWs H and F

AP

AP

FP

Wave crest

Wave trough(a) for EDW H

FP

Waterline(b) for EDW F－97－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 4)

Fig. 2

Definitions of ship motion
Lee side Weather side

Weather side2.

Lee side

Weather side down

Weather side up

bow down

bow upLoad cases

2.1
General
2.1.1
The load cases corresponding to the Equivalent Design Waves (EDWs) are defined in Table 1. The corresponding
hull girder loads and motions of the ship are indicated in Table 2. If the ship structure or the ship loading condition is
not symmetrical with respect to the centreline plane of ship, the load cases (R1, R2, P1 and P2) corresponding to thebeam conditions in which the encounter wave comes from the starboard (in this case the starboard is the weatherside), should be also included in the structural strength assessment.
Table 1
Load case

H1

H2

Definition of load cases

F1

F2

EDW

H

F

Heading

Head

Follow

Max. Bending Moment

Max. Bending Moment

Sagging

Sagging

R1

R2

P1

P2

R

P

Beam

Beam

(Port: weather side)(Port: weather side)

Max. Roll

Max. Ext. Pressure

EffectHogging

Table 2
Load case

H1

Hogging

(+)

(-)

(+)

(-)

Reference hull girder loads and motions of ship
H2

F1

F2

R1

R2

P1

P2

Vert. BM & SF

Yes

Yes

-

Yes

Hor. BM

-

-

Yes

-

Heave

Down

Up

-

-

Down

Up

Down

Up

Pitch

Bow down

Bow up

-

-

-

-

-

-

Roll

-

-

-

-

Stbd up

Stbd down

Stbd up

Stbd down

Surge

Stern

Bow

-

-

-

-

-

-

Sway

-

-

-

-

-

-

Port

Stbd

－98－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 4)

2.2
Load combination factors
2.2.1
The hull girder loads and the acceleration components to be considered in each load case H1, H2, F1, F2, R1, R2,
P1 and P2 are to be obtained by multiplying the reference value of each component by the relevant load combination
factor LCF defined in Table 3.
2.2.2
The still water vertical bending moment is to be added to the hull girder loads in waves, calculated with load
combination factors.
2.2.3
The internal loads are the sum of static pressures or forces induced by the weights carried, including those carriedon decks, and of inertial pressures or forces induced by the accelerations on these weights and calculated with load
combination factors.
Table 3

Load combination factors LCF

LCF

H1

H2

F1

F2

R1

R2

P1

MWV

CWV

-1

1

-1

1

0

0

0.4 -

TLC
TS

TLC
- 0.4
TS

QWV

CQW (1)

-1

1

-1

1

0

0

0.4 -

TLC
TS

TLC
- 0.4
TS

MWH

CWH

0

0

0

0

1.2 -

TLC
TS

P2

TLC
- 1.2
TS

0

0

asurge

CXS

-0.8

0.8

0

0

0

0

0

0

apitch x

CXP

1

-1

0

0

0

0

0

0

gsinF

CXG

1

-1

0

0

0

0

0

0

asway

CYS

0

0

0

0

0

0

1

-1

aroll y

CYR

0

0

0

0

1

-1

0.3

-0.3

gsinq

CYG

0

0

0

0

1

-1

0.3

-0.3

aheave

CZH

TLC
TS

T
- 0.6 LC
TS

0

0

1

-1

aroll z

CZR

0

0

0

0

1

-1

0.3

-0.3

apitch z

CZP

1

-1

0

0

0

0

0

0

0.6

LCSR - B
40-

LCSR - B
40(1) The LCF for CQW is only used for the aft part of midship section. The inverse value of it should be used for the forward
part of the midship section.

－99－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

Section 5

EXTERNAL PRESSURES

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Rule length LCSR-B, but to be taken not greater than 300 m: Wave coefficient, as defined in Ch 1, Sec 4, 2.3.1l: Wave length, in m, corresponding to the load case, defined in 1.3.1, 1.4.1 and 1.5.1: Coefficient corresponding to the probability, defined in Ch 4, Sec 2
fp
TLCi : Draught in the considered cross section, in m, in the considered loading condition: Moulded breadth at the waterline, in m, in the considered cross section
Bix, y, z : X, Y and Z co-ordinates, in m, of the load point with respect to the reference co-ordinate system defined in
Ch 1, Sec 4.
L2
C

1.

External sea pressures on side shell and bottom

1.1
General
1.1.1
The total pressure p at any point of the hull, in kN/m2, to be obtained from the following formula is not to be
negative:p = p S + pW
Where:
pS : Hydrostatic pressure defined in 1.2
pW : Wave pressure equal to the hydrodynamic pressure defined in 1.3, 1.4 or 1.5, as the case may be, andcorrected according to 1.6
1.2
Hydrostatic pressure
1.2.1
The hydrostatic pressure pS at any point of the hull, in kN/m2, corresponding to the draught in still water is obtained,
for each loading condition, from the formulae in Table 1 (see also Fig. 1).
Table 1

Hydrostatic pressure pS

Location
Points at and below the waterline ( z £ TLCi )Hydrostatic pressure, pS, in kN/m2
rg (T LCi - z )Points above the waterline ( z > TLCi )0

Hydrostatic pressure pS

PS= rgTLCi

TLCi

Fig. 1

PS= rgTLCi－100－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

1.3
Hydrodynamic pressures for load cases H1, H2, F1 and F2
1.3.1
The hydrodynamic pressures pH and pF, for load cases H1, H2, F1 and F2, at any point of the hull below thewaterline are to be obtained, in kN/m2, from Table 2.
The distribution of pressure pF2 is schematically given in Fig. 2.
Table 2

Hydrodynamic pressures for load cases H1, H2, F1 and F2
Load case

Hydrodynamic pressure, in kN/m2

H1

pH1 = - kl kp pHF

H2

pH2 = kl kp pHF

F1

pF1 = - pHF

F2

pF2 = pHF

where:
p HF = 3 f p f nl Cö2y
LCSR- B + l - 125 æ z
ç
+
+1 ;
ç
LCSR - B
Biè TLCi
ø

with

2y
Bi

£ 1.0 and z is to be taken not greater than TLCi

fnl : Coefficient considering nonlinear effect, taken equal to:for the probability level of 10-8
fnl = 0.9
fnl = 1.0
for the probability level of 10-4
kl : Amplitude coefficient in the longitudinal direction of the ship, taken equal to:32y ö x12 æçkl = 1 +1- 0 .5
for 0.0 £ x / LCSR -B £ 0.5
CB ç
B LCSR-Bèø
4y ö x6 æçkl = 1 +3- 0 .5
çCB è
B ø LCSR-B

3

for 0.5 £ x / LCSR -B £ 1.0

kp : Phase coefficient in the longitudinal direction of the ship, taken equal to:æT ö æ 2p x - 0.5 LCSR - B ö TLC
k p = çç1.25 - LC cosçç+ 0.25 , for local strength analysis in conditions otherTS ø èLCSR - Bèø TSthan full load condition, for direct strength analysis and for fatigue strength assessments
kp = -1.0 , for local strength analysis in full load conditionl : Wave length, in m, taken equal to:æ T ö
l = 0.6çç1 + LC LCSR-B
for load cases H1 and H2TS øèæ 2T ö
l = 0.6çç1 + LC LCSR - B for load cases F1 and F2
è 3 TS ø

Fig. 2Distribution of hydrodynamic pressure pF2 at midship－101－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

1.4
Hydrodynamic pressures for load cases R1 and R2
1.4.1
The hydrodynamic pressures pR, for load cases R1 and R2, at any point of the hull below the waterline are to beobtained, in kN/m2, from the following formulae. The distribution of pressure pR1 is schematically given in Fig.3.
æöö+ l - 125 æ 2 yLç+1
pR1 = f nl ç10 y sin q + 0.88 f pC CSR - Bç BçLCSR - Bèøøè
p R 2 = - p R1
where:
fnl : Coefficient considering nonlinear effect, taken equal to:for the probability level of 10-8
fnl = 0.8
fnl = 1.0
for the probability level of 10-4
g 2
l=
TR
2p
y : Y co-ordinate of the load point, in m, taken positive on the portside.
Fig. 3Distribution of hydrodynamic pressure pR1 at midship
Weather side

Lee side1.5
Hydrodynamic pressures for load cases P1 and P2
1.5.1
The hydrodynamic pressures pP, for the load cases P1 and P2, at any point of the hull below the waterline are to beobtained, in kN/m2, from Table 3. The distribution of pressure pP1 is schematically given in Fig. 4.
Table 3

Hydrodynamic pressures for load cases P1 and P2

Load case

Hydrodynamic pressure, in kN/m2
weather side

lee sideP1

pP1 = pP

pP1 = pP /3

P2

pP2 = - pP

pP2 = - pP /3

where:
pP = 4.5 f p f nl C

2y ö
LCSR - B + l - 125 æ z
ç2+3çLCSR - B
B øè TLCifnl : Coefficient considering nonlinear effect, taken equal to:for the probability level of 10-8
fnl = 0.65
fnl = 1.0
for the probability level of 10-4æT ö
l = çç 0.2 + 0.4 LC LCSR - BTS øèy : Y co-ordinate of the load point, in m, as defined in 1.4.1－102－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

Fig. 4

Distribution of hydrodynamic pressure pP1 at midship
Weather side

Lee side

1.6
Correction to hydrodynamic pressures
1.6.1
For the positive hydrodynamic pressure at the waterline (in load cases H1, H2, F2, R1, R2 and P1), thehydrodynamic pressure pW,C at the side above waterline is given (see Fig. 5), in kN/m2, by:for T LCi £ z £ hW + TLCi
・ pW ,C = pW ,WL + rg (T LCi - z )・for z ³ hW + TLCi

pW , C = 0

where:
pW,WL : positive hydrodynamic pressure at the waterline for the considered load case
pW ,WL
hW =
rg
1.6.2
For the negative hydrodynamic pressure at the waterline (in load cases H1, H2, F1, R1, R2 and P2), thehydrodynamic pressure pW,C, under the waterline is given (see Fig. 5), in kN/m2, by:
pW,C = pW , without being taken less than rg(z - TLCi)
where
pW : Negative hydrodynamic pressure under the waterline for the considered load caseFig. 5

Correction to hydrodynamic pressure

Weather side

Weather side
PW,WL
hW = PW,WL/( rg)

PW,C

PW,WL

Hydrodynamic
pressure

TLCi

HydrostaticpressurePW,C

rgTLCi

When hydrodynamic pressure is positive

When hydrodynamic pressure is negative－103－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)2.

External pressures on exposed decks

2.1
General2.1.1
The external pressures on exposed decks are to be applied for the local scantling check of the structures on exposed
deck but not applied for fatigue strength assessment.
If a breakwater is fitted on the exposed deck, no reduction in the external pressures defined in 2.2 and 2.3 isallowed for the area of the exposed deck located aft of the breakwater.
2.2
Load cases H1, H2, F1 and F2
2.2.1
The external pressure pD, for load cases H1, H2, F1 and F2, at any point of an exposed deck is to be obtained, in
kN/m2, from the following formula:p D = jpW
where:
pW : Pressure obtained from the formulae in Table 4
j : Coefficient defined in Table 5.
Table 4Pressures on exposed decks for H1, H2, F1 and F2
Pressure pW, in kN/m2

Location
LLL ³ 100 m

LLL < 100 m

0 £ xLL/LLL £ 0.75

34.3

14.9 + 0.195 LLL

0.75 < xLL/LLL < 1öæ x
34.3 + (14.8 + a (LLL - 100))çç 4 LL - 3
øè LLL

12.2 +

ö
LLL æ x LLxçç 5
- 2 + 3.6 LL
9 è LLL
LLL
øwhere:a: Coefficient taken equal to:a = 0.0726

for Type B freeboard ships

a = 0.356

for Type B-60 or Type B-100 freeboard ships.

xLL : X coordinate of the load point measured from the aft end of the freeboard length LLL

Table 5

Coefficient for pressure on exposed decks
Exposed deck locationjFreeboard deck

1.00

Superstructure deck, including forecastle deck

0.75

1st tier of deckhouse

0.56

2nd tier of deckhouse

0.42

3rd tier of deckhouse

0.32

4th tier of deckhouse

0.25

5th tier of deckhouse

0.20

6th tier of deckhouse

0.15

7th tier of deckhouse and above

0.10

2.3
Load cases R1, R2, P1 and P2
2.3.1
The external pressure pD, for load cases R1, R2, P1 and P2, at any point of an exposed deck is to be obtained, in
kN/m2, from the following formula:p D = 0.4 jpW
where:－104－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

pW : Hydrodynamic pressure at side of the exposed deck for the load cases P1, P2 , R1 and R2, in kN/m2,
can be determined by 1.6 at the z co-ordinate. pW is to be taken greater one of the hydrodynamic
pressures pW,C at both sides of the exposed deck (portside and starboard), and is not to be taken lessthan zero.
j : Coefficient defined in Table 5.
2.4
Load carried on exposed deck
2.4.1 Pressure due to distributed load
If a distributed load is carried on an exposed deck, the static pressure pS corresponding to this load is to be definedby the Designer and, in general, is not to be taken less than 10 kN/m2.
The total pressure p due to this load is to be considered not simultaneously to the pressures defined in 2.2 and 2.3.
It is to be taken equal, in kN/m2, to the greater value obtained from the following formulae:
p = p S + pW
p = pD

where:
pS : Static pressure due to the distributed load carried, if any
pW : Dynamic pressure due to the distributed load carried, in kN/m2, taken equal to:apW = Z p S
gaZ : Vertical acceleration at the centre of gravity of the distributed load carried for the load case considered,in m/s2, obtained by the formulae defined in Ch 4, Sec 2, 3.2
pD : Pressure for the exposed deck, for the load case considered, as defined in 2.2.1 and 2.3.1.
2.4.2 Concentrated forces due to unit load
If a unit load is carried on an exposed deck, the static and dynamic forces due to the unit load carried areconsidered.
The total force F due to this load is to be considered not simultaneously to the pressures defined in 2.2 and 2.3. It is
to be taken, in kN, equal to value obtained from the following formula:
F = FS + FW
where:
FS : Static force due to the unit load carried, in kN, taken equal to:
F S = mU g
FW : Dynamic force due to unit load carried, in kN, taken equal to:
FW = mU a Z
mU : Mass of the unit load carried, in t
aZ : Vertical acceleration at the centre of gravity of the unit load carried for the load case considered, in
m/s2, obtained by the formulae defined in Ch 4, Sec 2, 3.2.
3.

External pressures on superstructure and deckhouses

3.1
Exposed decks
3.1.1
External pressures on exposed decks of superstructures and deckhouses are to be obtained according to 2.
3.2
Exposed wheel house tops
3.2.1
The lateral pressure for exposed wheel house tops, in kN/m2, is not to be taken less than:p = 12.5
3.3
Sides of superstructures
3.3.1
The lateral pressure for sides of superstructures, in kN/m2, is to be obtained from the following formula:20
p SI = 2.1Cf p c F (C B + 0.7 )10 + z - T－105－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

f p : Probability factor, taken equal to:f p = 1 .0

for plate panels

f p = 0.75

for ordinary stiffeners and primary supporting members

c F : Distribution factor according to Table 6.

Table 6
Locationx0£< 0.2
LCSR -Bx
LCSR -B

Distribution factor cF
cF

5 æ
x ö
ç 0.2 , without taking x/LCSR-B less than 0.1
1.0 +C B çèLCSR -B ø

³ 0.2

1.0

3.4
End bulkhead of superstructure and deckhouse
3.4.1
The lateral pressure, in kN/m2, for determining the scantlings is to be obtained from the greater of the following
formulae:p A = nc[bC - ( z - T )]p A = p A min
where:n: Coefficient defined in Table 7, depending on the tier level.
The lowest tier is normally that tier which is directly situated above the uppermost continuous deck towhich the depth D is to be measured. However, where the actual distance (D-T) exceeds theminimum non-corrected tabular freeboard according to ILLC as amended by at least one standard
superstructure height as defined in Ch 1, Sec 4, 3.18.1, this tier may be defined as the 2nd tier and thetier above as the 3rd tierc
: Coefficient taken equal to:bc = 0 .3 + 0 .7 1
B1
For exposed parts of machinery casings, c is not to be taken less than 1.0
b1 : Breadth of deckhouse at the position considered
B1 : Actual maximum breadth of ship on the exposed weather deck at the position considered.
b1 / B1 is not to be taken less than 0.25b
: Coefficient defined in Table 8x: X co-ordinate, in m, of the calculation point for the bulkhead considered. When determining sides of a
deckhouse, the deckhouse is to be subdivided into parts of approximately equal length, not exceeding
0.15LCSR-B each, and x is to be taken as the X co-ordinate of the centre of each part considered.
z: Z co-ordinate, in m, of the midpoint of stiffener span, or to the middle of the plate fieldl: Span, in m, to be taken as the superstructure height or deckhouse height respectively, and not lessthan 2.0 m
pAmin : Minimum lateral pressure, in kN/m2, defined in Table 9.

－106－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

Table 7
Type ofCoefficient n

Locationbulkhead
Unprotected

n
L2
12
L
10 + 2
12
L
5+ 2
15
L
5+ 2
15
L
5+ 2
15
L2
x
7+
-8
100
L2
20 +

Lowest tier

front

Second tier
Third tier and above
Protected front

All tiers

Sides

All tiers

Aft end

Abaft amidships

5+

Forward of amidships

Table 8

L2
x
-4
100
L2

Coefficient b

Location of bulkheadbx< 0.45LCSR -Bæ x
ö
- 0.45ç
LCSR- B
ç
1.0 + çC B + 0.2çèøx
LCSR -B2

æ xö
- 0.45ç
LCSR- B
ç
1.0 + 1.5çC B + 0.2
çè
ø

³ 0.45

2

Where:
CB : Block coefficient with 0.6 £ C B £ 0.8 . When determining
scantlings of aft ends forward of amidships, C B need not betaken less than 0.8.

Table 9Minimum lateral pressure pAmin
pAmin, in kN/m2

LCSR - B
90 < LCSR -B £ 250

Lowest tier of unprotected

Elsewhere(1)fronts25 +LCSR - B
10

12.5 +LCSR - B
20

LCSR -B > 250
5025(1) For the 4th tier and above, p A min is to be taken equal to
12.5kN/m2.

－107－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

4.

Pressure in bow area

4.1
Bow flare area pressure
4.1.1
The bow pressure, in kN/m2, to be considered for the reinforcement of the bow flare area is to be obtained from thefollowing formula:p FB = K ( p S + pW )where:
pS, pW : Hydrostatic pressure and maximum hydrodynamic pressures among load cases H, F, R and P atconsidered point of the hull in normal ballast condition. Minimum ballast draught in ballast
condition TB defined in Ch 1, Sec 4, 2.1.1 is to be considered as TLCi for the calculation ofhydrostatic pressure and hydrodynamic pressures.
K: Coefficient taken equal to:)2(10 + z - TB ) to be taken not less than 1.0
2
æ
ö
æ
ö
20
x
ç
42C (C B + 0.7)ç1 +- 0.7
ç C B çè LCSR - Bø øè: Coefficient taken equal to:in generalcFL = 0.8
0 .4
c FL =
where the flare angle a is greater than 40
1.2 - 1.09 sin a
Where, the flare angle a at the load calculation point is to be measured in plane of the frame between avertical line and the tangent to the side shell plating. (see Fig. 7)
K=

cFL

(

cFL 0.2V + 0.6 LCSR - B

Fig. 7The definition of the flare angle
Plane of the framexFlare angleaload calculation point

z

TB

CL

tangent to the side
shell

4.2
Design bottom slamming pressure
4.2.1
The bottom slamming pressure, in kN/m2, to be considered for the reinforcement of the flat bottom forward is to beobtained from the following formula:・pSL = 162c1cSL LCSR - B

for LCSR-B £ 150m

－108－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 5)

・

pSL = 1984c1cSL (1.3 - 0.002LCSR - B )for LCSR-B > 150m

where:: Coefficient taken equal to:
c1
0.2

ö
æ T
c1 = 3.6 - 6.5çç BFP, to be taken not greater than 1.0
Lè CSR - B ø
TBFP : Smallest design ballast draught, in m, defined at forward perpendicular for normal ballast conditions.
Where the sequential method for ballast water exchange is intended to be applied, TBFP is to beconsidered for the sequence of exchange.
cSL : Distribution factor taken equal to (see Fig 6):xc SL = 0for£ 0.5
LCSR-Bx- 0.5
LCSR - B
c SL =
c2

for 0.5 <LCSR- B£ 0 .5 + c 2

x£ 0.65 + c2
LCSR- Bfor 0.5 + c2 <cSL = 1.0

c2

x

x ö
æ
ç 1LCSR - B
xc SL = 0.5ç1 +for> 0.65 + c2
ç
LCSR- B
0.35 - c2çøè: Coefficient taken equal to:Lc2 = 0.33C B + CSR-B , to be taken not greater than 0.35.
2500

Fig 6
1.0

Distribution factor cSL

cSL

0.5

0

0.5

0.6

0.7

0.8

0.9

1.0

x/LCSR-B
x/L

4.2.2
It is the Master s responsibility to observe, among others, the weather conditions and the draught at forward
perpendicular during water ballast exchange operations, in particular when the forward draught during these
operations is less than TBFP.
The above requirement and the draught TBFP is to be clearly indicated in the operating manuals.
5.

External pressures on hatch covers

5.1
General
5.1.1
If a specific load is carried on a hatch cover, the pressure is to be obtained according to 2.4.
5.2
Wave pressure
5.2.1
The pressure at any point of the hatch cover is to be obtained according to 2.2.1, considering j equal to 1.0.
However, when the hatchway is located at least one superstructure standard height, as defined in Ch 1, Sec 4, 3.18,
higher than the freeboard deck, the pressure pW may be taken equal to 34.3 kN/m2.

－109－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

Section 6

INTERNAL PRESSURES AND FORCES

SymbolsrC

For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Density of the dry bulk cargo, in t/m3, taken equal to:・ the value given in Table 1 for ships having a length (LCSR-B) of 150 m and above
・ the maximum density from the loading manual for ships having a length (LCSR-B) less than 150 m
Table 1

Density of dry bulk cargoDensity

Type of loading
Cargo hold loaded up to the upper deck
Cargo hold not loaded up to the upper deck

BC-A, BC-B

BC-C

max(MH/VH, 1.0)

1.0

3.0

(1)

-

(1) Except otherwise specified by the designer.

rL : Density of internal liquid, in t/m3, taken equal to 1.025 when internal liquid is ballast water
MH : The actual cargo mass in a cargo hold corresponding to a homogeneously loaded condition at maximum
draught, in t
VH : Volume, in m3, of cargo hold excluding the volume enclosed by hatch coaming
KC : Coefficient taken equal to:
K C = cos 2 a + (1 - sin y ) sin 2 a for inner bottom, hopper tank, transverse and longitudinal bulkheads, lower
stool, vertical upper stool, inner side and side shell:
K C = 0 for top side tank, upper deck and sloped upper stool:ay: Angle, in deg, between panel considered and the horizontal plane: Assumed angle of repose, in deg, of bulk cargo (considered drained and removed); in the absence of more
precise evaluation, the following values may be taken:
y = 30in generaly = 35for iron ore
y = 25for cement
hC : Vertical distance, in m, from the inner bottom to the upper surface of bulk cargo, as defined in 1.1.1 or 1.1.2
hDB : Height, in m, of the double bottom in the centrelinehLS : Mean height, in m, of the lower stool, measured from the inner bottom
zTOP : Z co-ordinate, in m, of the top of the tank, in upright conditionzBO : Z co-ordinate, in m, of the top of the overflow pipeaX : Longitudinal acceleration at the centre of gravity of the hold or tank considered, in m/s2, obtained by theformulae defined in Ch 4, Sec 2, 3.2
aY : Transverse acceleration at the centre of gravity of the hold or tank considered, in m/s2, obtained by theformulae defined in Ch 4, Sec 2, 3.2
aZ : Vertical acceleration at the centre of gravity of the hold or tank considered, in m/s2, obtained by the formulae
defined in Ch 4, Sec 2, 3.2
BH : Mean breadth of the cargo hold, in mbIB : Breadth of inner bottom, in m, as defined on Fig. 2
D1 : Distance, in m, from the base line to the freeboard deck at side amidships
sC : Spacing of corrugations, in m; see Ch 3, Sec 6, Fig. 28
x, y, z: X, Y and Z co-ordinates, in m, of the load point with respect to the reference co-ordinate system definedin Ch 1, Sec 4. y is to be taken positive on the weather side
xG, yG, zG : X, Y and Z co-ordinates, in m, of the centre of gravity of the hold or tank considered with respect to thereference co-ordinate system defined in Ch 1, Sec 4－110－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

dAP : Distance from the top of air pipe to the top of compartment, in m, taken equal to:dAP = zBO - zTOP

1.

Lateral pressure due to dry bulk cargo

1.1
Dry bulk cargo upper surface
1.1.1
When the dry bulk cargo density is such that the cargo hold is loaded to the top of hatch coaming, the uppersurface of the dry bulk cargo is an equivalent horizontal surface to be determined in considering the same loadedcargo volume in the considered hold bounded by the side shell or inner hull, as the case may be.
For holds of cylindrical shape, the equivalent horizontal surface of the dry bulk cargo may be taken at a distance hC,
in m, above the inner bottom obtained from the following formula (see Fig. 1):
hC = h HPU + h0
where:
S
h0 = ABH
S A = S0 +

V HC
lH

hHPU : Vertical distance, in m, between inner bottom and lower intersection of top side tank and side shell or
inner side, as the case may be, as defined in Fig. 1
S0 : Shaded area, in m2, above the lower intersection of top side tank and side shell or inner side, as thecase may be, and up to the upper deck level, as defined in Fig. 1
VHC : Volume, in m3, enclosed by the hatch coaming.
Fig. 1 Definitions of hC, h0, hHPU and S0

h0

S0

h0

S0

hC h
HPU

hHPU

Single side bulk carrier

hC

Double side bulk carrier

1.1.2
When the dry bulk cargo density is such that the cargo hold is not loaded up to the upper deck, the upper surface ofthe dry bulk cargo is considered as having a plane surface of width BH / 2 in the centreline and inclined parts with anangle equal to half the angle of repose ( y / 2) at sides, and is to be determined in considering the same loaded cargovolume in the considered hold, taken equal to M / r C .
For holds of cylindrical shape, the upper surface of the dry bulk cargo may be taken at a distance hC, in m, above
the inner bottom obtained from the following formula (see Fig. 2):
hC = h HPL + h1 + h2
where:
hHPL : Vertical distance, in m, between inner bottom and upper intersection of hopper tank and inner side, as
defined in Fig. 2. hHPL is to be taken equal to 0 if there is no hopper tank.
h1 : Vertical distance, in m, obtained from the following formula, see Fig. 2.

－111－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

h1 =

M
VTS

h2

B + b IB
V
M
3
y
- H
hHPL - B H tan + TS
2B H
16
2 BH l H
rC BH l H

: Mass, in t, of the bulk cargo to be considered, as defined in Ch 4, Sec 7: Total volume, in m3, of transverse stools at bottom of transverse bulkheads within the concernedcargo hold length lH. This volume excludes the part of hopper tank passing through the transverse
bulkhead.
: Bulk cargo upper surface, depending on y, given by:BByh2 = H tan(m), if 0 £ y £ H
4
2
4
BH
B
y
ö
æ BH
h 2 = çç- y tan(m), if£ y £ H
2
4
2
ø
è 2

For holds of non-cylindrical shape, and in case of prescriptive requirements, the upper surface of the bulk cargo
may be taken at the upper deck level with a density of dry bulk cargo equal to M/VH.
Fig. 2

Definitions of hC, h1, h2 and hHPL

Shape of bulk cargo surface for strength assessment

BH /2
h2

BH /2
h2

y /2

h1

hC

zC

hHPL

y /2

h1

hC

hHPL

bIB

bIB

Single side bulk carrier

Double side bulk carrier

1.2
Dry bulk cargo pressure in still water
1.2.1
The dry bulk cargo pressure in still water pCS, in kN/m2, is given by:
p CS = r C gK C (hC + h DB - z )1.3
Inertial pressure due to dry bulk cargo
1.3.1
The inertial pressure induced by dry bulk cargo pCW, in kN/m2, for each load case is given by the following
formulae.
p CW = r C [ 0.25a X ( x - x G ) + K C a Z (hC + h DB - z )]・ for load case H:
・ for load case F:
p CW = 0
・ for load cases R and P:
p CW = r C [ 0.25aY ( y - y G ) + K C a Z (hC + h DB - z )](x - xG) is to be taken as 0.25lH in the load case H1 or -0.25lH in the load case H2 for local strength by Ch 6 andfatigue check for longitudinal stiffeners by Ch 8.
The total pressure (pCS + pCW) is not to be negative.
1.4
Shear load due to dry bulk cargo
1.4.1
In order to evaluate the total force in the vertical direction, shear load due to dry bulk cargo acting along sloping
plates in way of bilge hopper tank and lower stool is to be considered.
The shear load due to dry bulk cargo acting along the sloping members in still water pCS-S (positive down to inner
bottom plating), in kN/m2, is given by:－112－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

p CS - S = r C g(1 - K C )(hC + hDB - z )tan a
The shear load due to dry bulk cargo acting along the sloping members in waves pCW-S (positive down to inner
bottom plating), in kN/m2, is given by:(1 - K C )(hC + hDB - z )・ for load cases H, R and P:
p CW - S = r C a Z
tan a・ for load case F:
p CW -S = 0

1.4.2
In order to evaluate the total force in the longitudinal and transverse directions, shear load due to dry bulk cargo in
way of inner bottom plating is to be considered.
The shear load due to dry bulk cargo in the longitudinal direction in waves pCW-S (positive forward), in kN/m2, isgiven by:・ for load case H:
pCW-S = 0.75 rC aX hC・ for load cases F, R and P:
pCW-S = 0
The shear load due to dry bulk cargo in the transverse direction in waves pCW-S (positive weather side), in kN/m2, isgiven by:・ for load cases R and P:
pCW-S = 0.75 rC aY hC・ for load cases H and F:
pCW-S = 02.

Lateral pressure due to liquid

2.1
Pressure due to liquid in still water
2.1.1
The liquid pressure in still water pBS, in kN/m2, is given by the greater of the following values:
p BS = r L g ( z TOP - z + 0.5d AP )p BS = r L g (z TOP - z ) + 100 PPV
where:
PPV : Setting pressure, in bar, of safety valves to be considered if any
For local strength assessments, the static pressure pBS is to be taken not less than 25 kN/m2.
2.1.2
When checking ballast water exchange operations by means of the flow through method, the static pressure pBS for
local strength assessments and direct strength analysis by Ch 7 is to be not less than:p BS = r L g (z TOP - z + d AP ) + 25
Additional calculation may be required where piping or pumping arrangements may lead to a higher pressure.
2.1.3
For fatigue strength assessment, the liquid pressure in still water pBS in kN/m2, is given by the following formula.
p BS = r L g ( z TOP - z )If the pBS is negative, pBS is to be taken equal to 0.
Where the considered load point is located in the fuel oil, other oils or fresh water tanks, liquids are assumed to be
fulfilled up to the half height of the tanks and zTOP is taken to the z coordinate of the liquid surface at the uprightcondition.
2.2
Inertial pressure due to liquid
2.2.1
The inertial pressure due to liquid pBW, in kN/m2, for each load case is given as follows. When checking ballast
water exchange operations by means of the flow through method, the inertial pressure due to ballast water is not to beconsidered for local strength assessments and direct strength analysis.
・ for load case H:
pBW = rL [aZ (zTOP z) + aX (x xB)]
(x - xB) is to be taken as 0.75lH in the load case H1 or -0.75lH in the load case H2 for local strength by Ch 6 andfatigue check for longitudinal stiffeners by Ch 8・ for load case F:
pBW = 0・ for load cases R and P: pBW = rL [aZ (zB z) + aY (y yB)]－113－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

where:
xB : X co-ordinate, in m, of the aft end of the tank when the bow side is downward, or of the fore end of thetank when the bow side is upward, as defined in Fig. 3
yB : Y co-ordinate, in m, of the tank top located at the most lee side when the weather side is downward, orof the most weather side when the weather side is upward, as defined in Fig. 3
zB : Z co-ordinate of the following point:
・ for completely filled spaces: the tank top
・ for ballast hold: the top of the hatch coaming
The reference point B is defined as the upper most point after rotation by the angle j between the vertical axis andr
the global acceleration vector AG shown in Fig. 3. j is obtained from the following formulae:
・ load cases H1 and H2:| aX |)
j = tan -1 (g cos F + a Z・ load cases R1(P1) and R2(P2):| aY |)
j = tan -1 (g cos q + a Z
where:
q : Single roll amplitude, in deg, defined in Ch4, Sec 2, 2.1.1
F : Single pitch amplitude, in deg, defined in Ch4, Sec 2, 2.2.1
The total pressure (pBS + pBW) is not to be negative.
Definition of xB and yB

Fig. 3
x-x
>
B

B

<0
x -x B

0

j

A

G

Ster

aX

n

j

j

aZ
gcos

aZ
gcos

F

Bow
y-yB>0Weather side <0y-y By-yB>0

j

j

B

z B-

AG

z B-

Bow

y-y

B< 0

j

zB -z
aZ
sq
gco

zB-z

AG
aX

Weather sidey-yB>0 B
j

F

n
Ster

B

Lee side

B

j

j

z

AG
a

aY

Y

z

a
Z
gco
sq
zB -z

Lee side
y-y

B >0

B

y-y
B<
0
y-y
B< 0
j

zB-z

－114－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

3.

Lateral pressures and forces in flooded condition

3.1
Application
3.1.1
The lateral pressures to be considered in flooded condition are indicated in:
3.2 in general cases
3.3 for the particular case of transverse corrugated bulkheads
3.4 for the particular case of double bottom
3.2
General
3.2.1
The pressure pF to be considered as acting on plating (excluding bottom and side shell plating) which constituteboundaries of compartments not intended to carry liquids is to be obtained, in kN/m2, from the following formula:a öæp F = rg çç1 + 0.6 Z ( z F - z ) , without being less than gd0
g øèwhere:
zF : Z co-ordinate, in m, of the freeboard deck at side in way of the transverse section considered. Where
the results of damage stability calculations are available, the deepest equilibrium waterline may beconsidered in lieu of the freeboard deck; in this case, the Society may require transient conditions to betaken into accountd0 : Distance, in m, to be taken equal to:d0 = 0.02LCSR-B for 90 m £ LCSR-B < 120 m
for LCSR-B ³ 120 m
d0 = 2.4
3.3
Transverse vertically corrugated watertight bulkheads
3.3.1 Application
Each cargo hold is to be considered individually flooded.
3.3.2 General
The loads to be considered as acting on each bulkhead are those given by the combination of those induced bycargo loads with those induced by the flooding of one hold adjacent to the bulkhead under examination. In any case,the pressure due to the flooding water alone is to be considered.
The most severe combinations of cargo induced loads and flooding loads are to be used for the check of thescantlings of each bulkhead, depending on the loading conditions included in the loading manual:・ homogeneous loading conditions
・ non-homogeneous loading conditions,considering the individual flooding of both loaded and empty holds.
For the purpose of this item, homogeneous loading condition means a loading condition in which the ratio between
the highest and the lowest filling ratio, evaluated for each hold, does not exceed 1.20, to be corrected for different
cargo densities.
Non-homogeneous part loading conditions associated with multiport loading and unloading operations forhomogeneous loading conditions need not be considered according to these requirements.
The specified design load limits for the cargo holds are to be represented by loading conditions defined by the
Designer in the loading manual.
For the purpose of this item, holds carrying packed cargoes are to be considered as empty.
Unless the ship is intended to carry, in non-homogeneous conditions, only iron ore or cargo having bulk density
equal to or greater than 1.78 t/m3, the maximum mass of cargo which may be carried in the hold is also to beconsidered to fill that hold up to the upper deck level at centreline.
3.3.3 Flooding level
The flooding level zF is the distance, in m, measured vertically from the base line with the ship in the uprightposition, and equal to:・ in general:・ D1 for the foremost transverse corrugated bulkhead
・ 0.9D1 for other bulkheads;－115－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

where the ship is to carry cargoes having bulk density less than 1.78 t/m3 in non-homogeneous loading
conditions, the following values may be assumed:
・ 0.95D1 for the foremost transverse corrugated bulkhead
・ 0.85D1 for other bulkheads
・ for ships less than 50000 t deadweight with type B freeboard:・ 0.95D1 for the foremost transverse corrugated bulkhead
・ 0.85D1 for other bulkheads;
where the ship is to carry cargoes having bulk density less than 1.78 t/m3 in non-homogeneous loading
conditions, the following values may be assumed:
・ 0.9D1 for the foremost transverse corrugated bulkhead
・ 0.8D1 for other bulkheads.
3.3.4 Pressures and forces on a corrugation in non-flooded bulk cargo loaded holds
At each point of the bulkhead, the pressure is to be obtained, in kN/m2, from the following formula:yöæ
p B = r C g (hC + h DB - z ) tan 2 ç 45 2ø
è
The force acting on a corrugation is to be obtained, in kN, from the following formula:(h - hLS )2 2 æ y ö
FB = r C gs C C
tan ç 45 22ø
è
3.3.5 Pressures and forces on a corrugation in flooded bulk cargo loaded holds
Two cases are to be considered, depending on the values of zF and hC (see 3.3.3 and 1.1):
・ First case, when zF ³ hC + hDB
At each point of the bulkhead located at a distance between zF and hC + hDB from the base line, the pressure, in
kN/m2, is to be obtained from the following formula:
pB,F = rg (zF z)
At each point of the bulkhead located at a distance lower than hC + hDB from the base line, the pressure, in kN/m2,
is to be obtained from the following formula:yöæp B, F = rg ( z F - z ) + [rC - r (1 - perm)]g (hC + hDB - z ) tan 2 ç 45 2ø
è
where perm is the permeability of cargo, to be taken as 0.3 for iron ore, coal cargoes and cement.
The force acting on a corrugation is to be obtained, in kN, from the following formula:é (z - hC - h DB )2 rg (z F - hC - h DB ) + ( p B , F )LEù+
FB , F = s C ê rg F
(hC - h LS )ú
2
2
ëê
ûú
where (pB,F)LE is the pressure pB,F, in kN/m2, calculated at the lower edge of the corrugation.
・ Second case, when zF < hC + hDB
At each point of the bulkhead located at a distance between zF and hC + hDB from the base line, the pressure is tobe obtained, in kN/m2, from the following formula:yöæp B, F = r C g (hC + h DB - z ) tan 2 ç 45 2øè
At each point of the bulkhead located at a distance lower than zF from the base line, the pressure is to beobtained, in kN/m2, from the following formula:yöæp B , F = rg ( z F - z ) + [r C (hC + h DB - z ) - r (1 - perm )( z F - z )]g tan 2 ç 45 2ø
è
where perm is the permeability of cargo, to be taken as 0.3 for iron ore, coal cargoes and cement.
The force acting on a corrugation is to be obtained, in kN, from the following formula:
ù
é
yö
2æ
+ ( pB , F )LE2
úê rC g (hC + hDB - z F ) tan ç 45 é
hC + hDB - z F )
(
y öù
2
è
ø
2æ
FB , F = sC ê rC g
tan ç 45 (z F - hDB - hLS )ú
ú + sC ê
ëê

2

è

2 øûú

ê
ê
ë

2

where (pB,F)LE is the pressure pB,F, in kN/m2, calculated at the lower edge of the corrugation.

－116－

ú
ú
û

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

3.3.6 Pressures and forces on a corrugation in flooded empty holds
At each point of the bulkhead, the still water pressure induced by the flooding to be considered is to be obtained, in
kN/m2, from the following formula:pF = rg (zF z)
The force acting on a corrugation is to be obtained, in kN, from the following formula:(z - h DB - hLS )2
FF = s C rg F
2
3.3.7 Resultant pressures and forces
Resultant pressures and forces to be calculated for homogeneous and non-homogeneous loading conditions are tobe obtained according to the following formulae:
・ Homogeneous loading conditions
At each point of the bulkhead structures, the resultant pressure to be considered for the scantlings of thebulkhead is to be obtained, in kN/m2, from the following formula:p = pB,F 0.8pB
The resultant force acting on a corrugation is to be obtained, in kN, from the following formula:
F = FB,F 0.8FB
where:
pB : Pressure in the non-flooded holds, in kN/m2, to be obtained as specified in 3.3.4
pB,F : Pressure in the flooded holds, in kN/m2, to be obtained as specified in 3.3.5
FB,F : Force acting on a corrugation in the flooded holds, in kN, to be obtained as specified in 3.3.5.
FB : Force acting on a corrugation in non-flooded holds, in kN, to be obtained as specified in 3.3.4.
・ Non-homogeneous loading conditions
At each point of the bulkhead structures, the resultant pressure to be considered for the scantlings of thebulkhead is to be obtained, in kN/m2, by the following formula:p = pB,FThe resultant force acting on a corrugation is to be obtained, in kN, by the following formula:
F = FB,F
where:
pB,F : Pressure in the flooded holds kN/m2, to be obtained as specified in 3.3.5
FB,F : Force acting on a corrugation in the flooded holds kN/m2, to be obtained as specified in 3.3.5.
3.4
Double bottom
3.4.1 Application
Each cargo hold is to be considered individually flooded.
3.4.2 General
The loads to be considered as acting on the double bottom are those given by the external sea pressures and the
combination of the cargo loads with those induced by the flooding of the hold which the double bottom belongs to.
The most severe combinations of cargo induced loads and flooding loads are to be used, depending on the loading
conditions included in the loading manual:・ homogeneous loading conditions
・ non-homogeneous loading conditions
・ packed cargo conditions (such as in the case of steel mill products).
For each loading condition, the maximum dry bulk cargo density to be carried is to be considered in calculating theallowable hold loading.
3.4.3 Flooding level
The flooding level zF is the distance, in m, measured vertically from the base line with the ship in the uprightposition, and equal to:・ for ships less than 50000 t deadweight with type B freeboard:・ 0.95D1 for the foremost hold・ 0.85D1 for other holds;
・ for other ships:
・ D1 for the foremost hold－117－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 6)

・ 0.9D1 for other holds;
4.

Testing lateral pressure

4.1
Still water pressures
4.1.1
The total pressure to be considered as acting on plates and stiffeners subject to tank testing is obtained, in kN/m2,
from the following formula:p ST = 10( z ST - z )where:
zST : Testing load height, in m, as defined in Table 2.
Table 2

Testing load height

Compartment or structure to be tested
Double bottom tanks

Testing load height, in m
The greater of the following:zST = zTOP + dAP
zST = zml

Hopper side tanks, topside tanks, double side

The greater of the following:tanks, fore and after peaks used as tank,zST = zTOP + dAP

cofferdams

zST = zTOP + 2.4

Tank bulkheads, deep tanks, fuel oil bunkers

The greater of the following:zST = zTOP + dAP
zST = zTOP + 2.4
zST = zTOP + 10pPV

Ballast hold

The greater of the following:zST = zTOP + dAP
zST = zh + 0.9

Fore and aft peak not used as tank

The greater of the following:zST = zF
zST = zml

Watertight doors below freeboard deckzST = zfd

Chain locker (if aft of collision bulkhead)zST = zTOP

Independent tanks

The greater of the following:zST = zTOP + dAP
zST = zTOP + 0.9

Ballast ducts

Testing load height corresponding toballast pump maximum pressure

where:
zml : Z co-ordinate, in m, of the bulkhead deck at side.
zh: Z co-ordinate, in m, of the top of hatch coaming.

zF: As defined in 3.2.1.

zfd : Z co-ordinate, in m, of the freeboard deck.
pPV : Setting pressure, in bar, of safety valves.

－118－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 7)

Section 7

LOADING CONDITIONS

SymbolsMH
MFull: The actual cargo mass in a cargo hold corresponding to a homogeneously loaded condition at maximum
draught, in t
: The cargo mass in a cargo hold corresponding to cargo with virtual density (homogenous mass / hold cubic
capacity, minimum 1.0 t/m3) filled to the top of the hatch coaming, in t.
M Full = V Full max( M H / V H , 1.0)

MFull is in no case to be less than MH
MHD : The maximum cargo mass allowed to be carried in a cargo hold according to design loading condition(s)with specified holds empty at maximum draught, in t
VFull : Volume, in m3, of the cargo hold including the volume enclosed by the hatch coaming: Volume, in m3, defined in Ch 4, Sec 6
VH
THB : Deepest ballast draught, in m.

1.

Application

1.1
Ships having a length (LCSR-B) less than 150 m
1.1.1
The severest loading conditions from the loading manual, midship section drawing or otherwise specified by the
Designer are to be considered for the longitudinal strength according to Ch 5, Sec 1 and for the local strength checkof plating, ordinary stiffeners and primary supporting members according to Ch 6.
1.2
Ships having a length (LCSR-B) of 150 m and above
1.2.1
The requirements in 2 to 4 are applicable to ships having a length (LCSR-B) of 150 m and above.
1.2.2
These requirements are not intended to prevent any other loading conditions to be included in the loading manual
for which calculations are to be submitted. It is not intended to replace in any way the required loading
manual/instrument.
1.2.3
The maximum loading condition draught is to be taken as the moulded summer load line draught.
1.2.4
The loading conditions listed in 2 are to be applied for the check of longitudinal strength as required by Ch 5, Sec
1, the check of local strength by Ch 6, the direct strength analysis by Ch 7, for capacity and disposition of ballast
tanks and stability purposes. The loading conditions listed in 3 are to be applied for the check of local strength. The
loading conditions listed in 4 are to be applied for direct strength analysis.
1.2.5
In operation, a bulk carrier may be loaded differently from the design loading conditions specified in the loading
manual, provided longitudinal and local strength as defined in the loading manual and onboard loading instrument
and applicable stability requirements are not exceeded.
2.

General

2.1
Design loading conditions - General
2.1.1
For the determination of the maximum cargo mass in cargo holds, the condition corresponding to the ship being
loaded at maximum draught with 50% of consumables is to be considered.

－119－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 7)

2.1.2 BC-C
Homogeneous cargo loaded condition where the cargo density corresponds to all cargo holds, including hatchways,
being 100% full at maximum draught with all ballast tanks empty.
2.1.3 BC-B
As required for BC-C, plus:
Homogeneous cargo loaded condition with cargo density 3.0 t/m3, and the same filling ratio (cargo mass/hold cubic
capacity) in all cargo holds at maximum draught with all ballast tanks empty.
In cases where the cargo density applied for this design loading condition is less than 3.0 t/m3, the maximum
density of the cargo that the ship is allowed to carry is to be indicated with the additional service feature {maximum
cargo density x.y t/m3}.
2.1.4 BC-A
As required for BC-B, plus:
At least one cargo loaded condition with specified holds empty, with cargo density 3.0 t/m3, and the same filling
ratio (cargo mass/hold cubic capacity) in all loaded cargo holds at maximum draught with all ballast tanks empty.
The combination of specified empty holds is to be indicated with the additional service feature {holds a, b, ... may
be empty}.
In such cases where the design cargo density applied is less than 3.0 t/m3, the maximum density of the cargo thatthe ship is allowed to carry is to be indicated within the additional service feature {holds a, b, ... may be empty withmaximum cargo density x.y t/m3}.
2.2
Applicable ballast conditions
2.2.1 Ballast tank capacity and disposition
All bulk carriers are to have ballast tanks of sufficient capacity and so disposed to at least fulfill the following
requirements.
・ Normal ballast condition
Normal ballast condition is a ballast (no cargo) condition where:
・ the ballast tanks may be full, partially full or empty. Where ballast tanks are partially full, the conditions in
Ch 4, Sec 3 are to be complied with・ any cargo hold or holds adapted for the carriage of water ballast at sea are to be empty
・ the propeller is to be fully immersed, and・ the trim is to be by the stern and is not to exceed 0.015LBP.
In the assessment of the propeller immersion and trim, the draughts at the forward and after perpendiculars may
be used.
・ Heavy ballast condition
Heavy ballast condition is a ballast (no cargo) condition where:
・ the ballast tanks may be full, partially full or empty. Where ballast tanks are partially full, the conditions in
Ch 4, Sec 3 are to be complied with・ at least one cargo hold adapted for carriage of water ballast at sea is to be full・ the propeller immersion I/D is to be at least 60 %, where:
I = Distance from propeller centerline to the waterline
D = Propeller diameter・ the trim is to be by the stern and is not to exceed 0.015LBP・ the moulded forward draught in the heavy ballast condition is not to be less than the smaller of 0.03LBP or
8 m.
2.2.2 Strength requirements
All bulk carriers are to meet the following strength requirements:
・ Normal ballast condition:・ the structures of bottom forward are to be strengthened in accordance with the requirements of this Partagainst slamming for the condition of 2.2.1 for normal ballast condition at the lightest forward draught,
・ the longitudinal strength requirements according to Ch 4, Sec 3 are to be met for the condition of 2.2.1 fornormal ballast condition, and－120－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 7)

・ in addition, the longitudinal strength requirements according to Ch 4, Sec 3 are to be met with all ballast
tanks 100% full.
・ Heavy ballast condition:・ the longitudinal strength requirements according to Ch 4, Sec 3 are to be met for the condition of 2.2.1 forheavy ballast condition
・ in addition, the longitudinal strength requirements according to Ch 4, Sec 3 are to be met with all ballast
tanks 100% full and one cargo hold adapted and designated for the carriage of water ballast at sea, where
provided, 100% full, and・ where more than one hold is adapted and designated for the carriage of water ballast at sea, it will not be
required that two or more holds be assumed 100% full simultaneously in the longitudinal strength
assessment, unless such conditions are expected in the heavy ballast condition. Unless each hold isindividually investigated, the designated heavy ballast hold and any/all restrictions for the use of otherballast hold(s) are to be indicated in the loading manual.
2.3
Departure and arrival conditions
2.3.1
Unless otherwise specified, each of the design loading conditions defined in 2.1 and 2.2 is to be investigated forthe arrival and departure conditions as defined as follows:・ Departure condition : with bunker tanks not less than 95% full and other consumables 100%・ Arrival condition : with 10% of consumables
3.

Design loading conditions for local strength

3.1
Definitions
3.1.1
The maximum allowable or minimum required cargo mass in a cargo hold, or in two adjacently loaded holds, isrelated to the net load on the double bottom. The net load on the double bottom is a function of draft, cargo mass inthe cargo hold, as well as the mass of fuel oil and ballast water contained in double bottom tanks.
3.2
Applicable general conditions
3.2.1
Any cargo hold is to be capable of carrying MFull with fuel oil tanks in double bottom in way of the cargo hold, if
any, being 100% full and ballast water tanks in the double bottom in way of the cargo hold being empty, at maximum
draught.
3.2.2
Any cargo hold is to be capable of carrying minimum 50% of MH, with all double bottom tanks in way of the cargohold being empty, at maximum draught.
3.2.3
Any cargo hold is to be capable of being empty, with all double bottom tanks in way of the cargo hold being empty,
at the deepest ballast draught.
3.3
Additional conditions applicable except when additional service feature {no MP} is assigned
3.3.1
Any cargo hold is to be capable of carrying MFull with fuel oil tanks in double bottom in way of the cargo hold, if
any, being 100% full and ballast water tanks in the double bottom in way of the cargo hold being empty, at 67% of
maximum draught.
3.3.2
Any cargo hold is to be capable of being empty with all double bottom tanks in way of the cargo hold being empty,
at 83% of maximum draught.
3.3.3
Any two adjacent cargo holds are to be capable of carrying MFull with fuel oil tanks in double bottom in way of the
cargo hold, if any, being 100% full and ballast water tanks in the double bottom in way of the cargo hold being empty,
at 67% of the maximum draught. This requirement to the mass of cargo and fuel oil in double bottom tanks in way ofthe cargo hold applies also to the condition where the adjacent hold is filled with ballast, if applicable.
－121－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 7)

3.3.4
Any two adjacent cargo holds are to be capable of being empty, with all double bottom tanks in way of the cargohold being empty, at 75% of maximum draught.
3.4
Additional conditions applicable for BC-A only
3.4.1
Cargo holds, which are intended to be empty at maximum draught, are to be capable of being empty with all
double bottom tanks in way of the cargo hold also being empty.
3.4.2
Cargo holds, which are intended to be loaded with high density cargo, are to be capable of carrying MHD plus 10%of MH, with fuel oil tanks in the double bottom in way of the cargo hold, if any, being 100% full and ballast watertanks in the double bottom being empty in way of the cargo hold, at maximum draught.
In operation the maximum allowable cargo mass shall be limited to MHD.
3.4.3
Any two adjacent cargo holds which according to a design loading condition may be loaded with the next holds
being empty, are to be capable of carrying 10% of MH in each hold in addition to the maximum cargo load according
to that design loading condition, with fuel oil tanks in the double bottom in way of the cargo hold, if any, being 100%
full and ballast water tanks in the double bottom in way of the cargo hold being empty, at maximum draught.
In operation the maximum allowable mass shall be limited to the maximum cargo load according to the design
loading conditions.
3.5
Additional conditions applicable for ballast hold(s) only
3.5.1
Cargo holds, which are designed as ballast water holds, are to be capable of being 100% full of ballast water
including hatchways, with all double bottom tanks in way of the cargo hold being 100% full, at any heavy ballast
draught. For ballast holds adjacent to topside wing, hopper and double bottom tanks, it shall be strengthwise
acceptable that the ballast holds are filled when the topside wing, hopper and double bottom tanks are empty.
3.6
Additional conditions applicable during loading and unloading in harbour only
3.6.1
Any single cargo hold is to be capable of holding the maximum allowable seagoing mass at 67% of maximum
draught, in harbour condition.
3.6.2
Any two adjacent cargo holds are to be capable of carrying MFull, with fuel oil tanks in the double bottom in wayof the cargo hold, if any, being 100% full and ballast water tanks in the double bottom in way of the cargo hold being
empty, at 67% of maximum draught, in harbour condition.
3.6.3
At reduced draught during loading and unloading in harbour, the maximum allowable mass in a cargo hold may be
increased by 15% of the maximum mass allowed at the maximum draught in sea-going condition, but shall not
exceed the mass allowed at maximum draught in the sea-going condition. The minimum required mass may be
reduced by the same amount.
3.7
Hold mass curves
3.7.1
Based on the design loading criteria for local strength, as given in 3.2 to 3.6 except 3.5.1, hold mass curves are to
be included in the loading manual and the loading instrument, showing maximum allowable and minimum required
mass as a function of draught in sea-going condition as well as during loading and unloading in harbour. Hold mass
curves are to be calculated according to Ch 4, App 1.
3.7.2
At other draughts than those specified in the design loading conditions, the maximum allowable and minimum
required mass is to be adjusted for the change in buoyancy acting on the bottom. Change in buoyancy is to be
calculated using water plane area at each draught.
Hold mass curves for each single hold, as well as for any two adjacent holds, are to be included in the loading
manual and the loading instrument.
－122－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 7)

4.

Design loading conditions for direct strength analysis

4.1
Loading patterns
4.1.1
The loading patterns applicable to types of bulk carriers with various service feature notations are summarized inTable 1, which are to be considered in direct strength analysis in accordance with 2 and 3.
Table 1
No.

Applicable loading patterns according to additional service features
Loading pattern

BC-

Ref.

BC-, (no MP)

A

B

C

A

B

C

Full load in homogeneous1

condition

3.2.1

x

x

x

x

x

x

2

Slack load

3.2.2

x

x

x

x

x

x

3

Deepest ballast

3.2.3

x

x

x

x

x

x

4

Multiport -1

3.3.1

x

x

x

5

Multiport -2

3.3.2

x

x

x

6

Multiport -3

3.3.3

x

x

x

7

Multiport -4

3.3.4

x

x

x

8

Alternate load

3.4.1&.2xx

9

Alternate block load

3.4.3

x

x

10

Heavy ballast

3.5.1

x

x

x

x

11

Harbour condition -1

3.6.1

x

x

x

12

Harbour condition -2

3.6.2

x

x

x

x

x

4.1.2
Other loading conditions from the loading manual, which are not covered in Table 1, if any, are also to beconsidered.
4.2
Still water bending moment and shear force
4.2.1
Load cases defined in Sec 4 are to be considered for each loading pattern given in Table 1. The still water verticalbending moment provided in Table 2 and the still water vertical shear force provided in Table 3 are to be used foreach combination of loading pattern and load case.
4.2.2
If one loading condition in the loading manual has a still water vertical bending moment more severe than thevalue in Table 2 for the corresponding loading pattern, the value in Table 2 for this loading pattern is to be replacedwith the value from the loading manual.
4.3
Application
4.3.1
The minimum required loading conditions for direct strength analysis, including vertical shear force analysis, aredefined in Ch 4, App 2.
4.3.2
The standard loading conditions for fatigue assessment are defined in Ch 4, App 3.

－123－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 7)

Table 2

Vertical still water bending moment
Loading pattern
Slack load

Full load in
condition

Load case

Alternate

Alternate load

homogeneous

block load

Heavy ballast

Harbour(Ballast hold)condition

DeepestNormal ballast

ballastH1

0.5MSW,S

0

MSW,S

MSW,S

H2

0.5MSW,H

MSW,H

MSW,H

0

F1

0.5 MSW,S

0

MSW,S

MSW,S

F2

0.5MSW,H

MSW,H

MSW,H

0

0.5 MSW,S

0

MSW,S

MSW,S

0.5MSW,H

MSW,H

MSW,H

0

0.5 MSW,S

0

MSW,S

MSW,S

0.5MSW,H

MSW,H

MSW,H

0

P1

0.5 MSW,S

0

MSW,S

MSW,S

P2

0.5MSW,H

MSW,H

MSW,H

0

R1

R2

Staticwhere:MSW,H
MSW,S
MSW,P,H
MSW,P,S

Multiport

:
:
:
:

---

MSW,P,S---

MSW,P,H

Allowable still water vertical bending moment in hogging condition for seagoing condition
Allowable still water vertical bending moment in sagging condition for seagoing condition
Allowable still water vertical bending moment in hogging condition for harbour condition
Allowable still water vertical bending moment in sagging condition for harbour condition
Table 3

Vertical still water shear force
Loading pattern

Full load inhomogeneous

Load casecondition

Alternate load
(BC-A)

Multiport(BC-B andBC-C)

Heavy ballast(Ballast hold)

Heavy ballast(Except for
ballast hold)

H1

---

QSW

QSW

QSW

---

H2

---

QSW

QSW

QSW

---

F1

---

QSW

QSW

QSW

---

F2

---

QSW

QSW

QSW

---

where:QSW: Allowable still water shear force at the position of the considered transverse bulkhead－124－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 8)

Section 8
1.

LOADING MANUAL AND LOADING INSTRUMENT

General1.1
All ships
1.1.1
An approved loading manual is to be supplied on board for all ships.
In addition, an approved loading instrument is to be supplied for all ships.
The loading instrument is ship specific onboard equipment and the results of the calculations are only applicable tothe ship for which it has been approved.
An approved loading instrument may not replace an approved loading manual.
1.2
Ships equal to or greater than 150 m in length (LCSR-B)
1.2.1
BC-A, BC-B and BC-C ships are to be provided with an approved loading manual and an approved computer-basedloading instrument, in accordance with the applicable requirements of this Section.
A guidance for loading and unloading sequences is given in 5.
2.

Loading manual

2.1
Definitions
2.1.1 All ships
A loading manual is a document which describes:
・ the loading conditions on which the design of the ship has been based, including permissible limits of still water
bending moment and shear force. The conditions specified in the ballast water exchanging procedure and dry
docking procedure are to be included in the loading manual.
・ the results of the calculations of still water bending moments and shear forces
・ the allowable local loading for the structure (hatch covers, decks, double bottom, etc.).
2.1.2 Ships equal to or greater than 150 m in length (LCSR-B)
In addition to 2.1.1, for BC-A, BC-B and BC-C ships, the loading manual is also to describe:・ envelope results and permissible limits of still water bending moments and shear forces in the hold flooded
condition according to Ch 5, Sec 1・ the cargo hold(s) or combination of cargo holds that might be empty at full draught. If no cargo hold is allowed
to be empty at full draught, this is to be clearly stated in the loading manual・ maximum allowable and minimum required mass of cargo and double bottom contents of each hold as afunction of the draught at mid-hold position
・ maximum allowable and minimum required mass of cargo and double bottom contents of any two adjacent
holds as a function of the mean draught in way of these holds. This mean draught may be calculated byaveraging the draught of the two mid-hold positions
・ maximum allowable tank top loading together with specification of the nature of the cargo for cargoes other thanbulk cargoes
・ maximum allowable load on deck and hatch covers. If the ship is not approved to carry load on deck or hatch
covers, this is to be clearly stated in the loading manual・ maximum rate of ballast change together with the advice that a load plan is to be agreed with the terminal on thebasis of the achievable rates of change of ballast.
2.2
Conditions of approval
2.2.1 All ships
The approved loading manual is to be based on the final data of the ship. The manual is to include the design(cargo and ballast) loading conditions, subdivided into departure and arrival conditions as appropriate, upon which
the approval of the hull scantlings is based.

－125－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 8)

In the case of modifications resulting in changes to the main data of the ship, a new approved loading manual is tobe issued.
2.2.2 Ships equal to or greater than 150 m in length (LCSR-B)
In addition to 2.2.1, for BC-A, BC-B and BC-C ships, the following loading conditions, subdivided into departureand arrival conditions as appropriate, are also to be included in the loading manual:・ homogeneous light and heavy cargo loading conditions at maximum draught
・ alternate light and heavy cargo loading conditions at maximum draught, where applicable・ ballast conditions. For ships having ballast holds adjacent to topside wing, hopper and double bottom tanks, it
shall be strengthwise acceptable that the ballast holds are filled when the topside wing, hopper and double
bottom tanks are empty
・ short voyage conditions where the ship is to be loaded to maximum draught but with limited amount of bunkers
・ multiple port loading / unloading conditions
・ deck cargo conditions, where applicable・ typical loading sequences where the ship is loaded from commencement of cargo loading to reaching fulldeadweight capacity, for homogeneous conditions, relevant part load conditions and alternate conditions whereapplicable. Typical unloading sequences for these conditions are also to be included. The typical loading /unloading sequences are also to be developed to not exceed applicable strength limitations. The typical loading
sequences are also to be developed paying due attention to loading rate and the deballasting capability. Table 1
contains, as guidance only, an example of a Loading Sequence Summary Form・ typical sequences for change of ballast at sea, where applicable.
2.3
Language
2.3.1
The loading manual is to be prepared in a language understood by the users. If this language is not English, atranslation into English is to be included.
3.

Loading instrument

3.1
Definitions
3.1.1 All ships
A loading instrument is an instrument which is either analog or digital and by means of which it can be easily andquickly ascertained that, at specified read-out points, the still water bending moments, shear forces, in any load orballast condition, do not exceed the specified permissible values.
3.1.2 Ships equal to or greater than 150 m in length (LCSR-B)
For BC-A, BC-B and BC-C ships, the loading instrument is an approved digital system as defined in 3.1.1. In
addition to 3.1.1, it is also to ascertain as applicable that:・ the mass of cargo and double bottom contents in way of each hold as a function of the draught at mid-holdposition・ the mass of cargo and double bottom contents of any two adjacent holds as a function of the mean draught in
way of these holds
・ the still water bending moment and shear forces in the hold flooded conditions do not exceed the specified
permissible values.
3.2
Conditions of approval
3.2.1 All ships
The loading instrument is subject to approval, which is to include:・ verification of type approval, if any
・ verification that the final data of the ship have been used
・ acceptance of number and position of all read-out points
・ acceptance of relevant limits for read-out points
・ checking of proper installation and operation of the instrument on board, under agreed test conditions, and that a
copy of the operation manual is available.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 8)

3.2.2 Ships equal to or greater than 150 m in length (LCSR-B)
In addition, for BC-A, BC-B and BC-C ships, the approval is also to include, as applicable:・ acceptance of hull girder bending moment limits for all read-out points
・ acceptance of hull girder shear force limits for all read-out points
・ acceptance of limits for the mass of cargo and double bottom contents of each hold as a function of draught
・ acceptance of limits for the mass of cargo and double bottom contents in any two adjacent holds as a function ofdraught.
3.2.3
In the case of modifications implying changes in the main data of the ship, the loading instrument is to be modified
accordingly and approved.
3.2.4
An operational manual is always to be provided for the loading instrument.
The operation manual and the instrument output are to be prepared in a language understood by the users. If thislanguage is not English, a translation into English is to be included.
3.2.5
The operation of the loading instrument is to be verified upon installation under the agreed test conditions. It is tobe checked that the agreed test conditions and the operation manual for the instrument are available on board.
4.

Annual and class renewal survey

4.1
General
4.1.1
At each annual and class renewal survey, it is to be checked that the approved loading manual is available onboard.
4.1.2
The loading instrument is to be checked for accuracy at regular intervals by the ship's Master by applying test
loading conditions.
4.1.3
At each class renewal survey this checking is to be done in the presence of the Surveyor.
5.

Guidance for loading/unloading sequences

5.1
General
5.1.1
The typical loading/unloading sequences shall be developed paying due attention to the loading/unloading rate, theballasting/deballasting capacity and the applicable strength limitations.
5.1.2
The shipbuilder will be required to prepare and submit for approval typical loading and unloading sequences.
5.1.3
The typical loading sequences as relevant should include:・ alternate light and heavy cargo load condition
・ homogeneous light and heavy cargo load condition
・ short voyage condition where the ship is loaded to maximum draught but with limited bunkers
・ multiple port loading/unloading condition・ deck cargo condition
・ block loading.
5.1.4
The loading/unloading sequences may be port specific or typical.
5.1.5
The sequence is to be built up step by step from commencement of cargo loading to reaching full deadweightcapacity. Each time the loading equipment changes position to a new hold defines a step. Each step is to be
documented and submitted to the Society. In addition to longitudinal strength, the local strength of each hold is to beconsidered.
－127－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 8)

5.1.6
For each loading condition a summary of all steps is to be included. This summary is to highlight the essential
information for each step such as:・ how much cargo is filled in each hold during the different steps,
・ how much ballast is discharged from each ballast tank during the different steps,
・ the maximum still water bending moment and shear at the end of each step,・ the ship s trim and draught at the end of each step.

－128－

Table 1

Guidance on Typical Loading Sequence Summary Form2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Section 8)－129－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 1)

Appendix 1

HOLD MASS CURVES

Symbolshha: Vertical distance from the top of inner bottom plating to upper deck plating at the ship s centreline, in m.
: Vertical distance from the top of inner bottom plating to the lowest point of the upper deck plating at theship s centreline of the aft cargo hold in a block loading, in m.
hf: Vertical distance from the top of inner bottom plating to the lowest point of the upper deck plating at theship s centreline of the fore cargo hold in block loading, in m.
: As defined in Ch 4, Sec 7
MH: As defined in Ch 4, Sec 7
MFull: As defined in Ch 4, Sec 7
MHD: The maximum cargo mass given for each cargo hold, in t
MD
: The maximum cargo mass in a cargo hold according to the block loading condition in the loading manual,
MBLK
in t
: As defined in Ch 4, Sec 7
THB
Ti: Draught in loading condition No. i, at mid-hold position of cargo hold length lH , in m
: As defined in Ch 4, Sec 6
VH
Vf and Va : Volume of the forward and after cargo hold excluding volume of the hatchway part, in m3.
: 0.75TS or draught in ballast conditions with the two adjacent cargo holds empty, whichever is greater,
Tmin
in m.
: The sum of masses of two adjacent cargo holds
S

1.

General1.1
Application
1.1.1
The requirements of this Appendix apply to ships of 150 m in length (LCSR-B) and above.
1.1.2
This Appendix describes the procedure to be used for determination of:・ the maximum and minimum mass of cargo in each cargo hold as a function of the draught at mid-hold positionof cargo hold・ the maximum and minimum mass of cargo in any two adjacent holds as a function of the mean draught in wayof these holds.
1.1.3
Results of these calculations are to be included in the reviewed loading manual which has also to indicate themaximum permissible mass of cargo at scantling draught in each hold or in any two adjacent holds, as obtained fromthe design review.
1.1.4
The following notice on referring to the maximum permissible and the minimum required mass of cargo is to be
described in loading manual.
Where ship engages in a service to carry such hot coils or heavy cargoes that have some adverse effect on the local
strength of the double bottom and that the loading is not described as cargo in loading manual, the maximum
permissible and the minimum required mass of cargo are to be considered specially.

－130－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 1)

2.

Maximum and minimum masses of cargo in each hold2.1

Maximum permissible mass and minimum required masses of single cargo hold in seagoingcondition
2.1.1 General
The cargo mass curves of single cargo hold in seagoing condition are defined in 2.1.2 to 2.1.5. However if the ship
structure is checked for more severe loading conditions than the ones considered in Ch 4, Sec 7, 3.7.1, the minimum
required cargo mass and the maximum allowable cargo mass can be based on those corresponding loading
conditions.
2.1.2 BC-A ship not having {No MP} assigned
・ For loaded holds
The maximum permissible mass ( Wmax (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following
formulae:
Wmax (Ti ) = M HD + 0.1M H - 1.025VH(TS - Ti )hHowever, Wmax (Ti ) is no case to be greater than MHD.
The minimum required cargo mass ( W min (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following

formulae:
Wmin (Ti ) = 0

for Ti £ 0.83TS(Ti - 0.83TS )for TS ³ Ti > 0.83TSh・ For empty holds which can be empty at the maximum draught
The maximum permissible mass ( Wmax (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following
Wmin (Ti ) = 1.025V H

formulae:
W max (Ti ) = M Fullfor TS ³ Ti ³ 0.67T S(0.67TS - Ti )for Ti < 0.67T S
h
The minimum required mass ( W min (Ti ) ) is obtained, in t, by the following formula:
W min (Ti ) = 0
for Ti £ TS
Wmax (Ti ) = M Full - 1.025V H

Examples for mass curve of loaded cargo hold and cargo hold which can be empty at the maximum draught for
BC-A ships not having {No MP} assigned are shown in Fig. 1.
Fig. 1

Example of mass curve for BC-A ships not having {No MP} assigned
1.15MHD + 0.1MH
MHD + 0.1MH
MHD

Harbour0

Cargo mass

Cargo mass

Harbour

0.15MHD

Seagoing
0.67TS 0.83TS TS Draught(a) Loaded hold

1.15MFull
MFull

0

0.15MFull

Seagoing

0.67TSTS Draught(b) Cargo hold which can be empty at the maximum draught

2.1.3 BC-A ship having {No MP} assigned
・ For loaded holds
The maximum permissible mass ( W max (Ti ) ) at various draughts ( Ti ) is the same specified in 2.1.2.
The minimum required mass ( W min (Ti ) ) is obtained, in t, by the following formulae:
W min (Ti ) = 0
for Ti £ THB－131－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 1)

Wmin (Ti ) = 1.025V H(Ti - THB )hfor TS ³ Ti > T HBor(TS - Ti ) ³ 0

for TS ³ Ti
h・ For empty hold which can be empty at the maximum draught
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following formulae:
T - TiW max (Ti ) = M Full - 1 .025V H ShThe minimum required cargo mass ( Wmin(Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following
W min (Ti ) = 0 .5 M H - 1.025V H

formulae:
Wmin (Ti ) = 0

for

Ti £ Ts

Examples for mass curve of cargo hold for BC-A ships, having {No MP} assigned are shown in Fig. 2.
Fig. 2

Example of mass curve for BC-A ships having {No MP} assigned
1.15MHD + 0.1MH
MHD + 0.1MH
MHD

1.15MFull
MFull

HarbourCargo mass

Cargo mass

Harbour

0.15MHD
0.5MH

Seagoing

0

THB 0.67TS

Seagoing
0.67TS0

TS Draught(a) Loaded hold

0.15MFull

TS Draught(b) Cargo hold which can be empty at the maximum draught

2.1.4 BC-B and BC-C ships not having {No MP} assigned
The maximum permissible mass ( W max (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following formulae:
W max (Ti ) = M Fullfor TS ³ Ti ³ 0.67T S(0.67TS - Ti )Wmax (Ti ) = M Full - 1.025V H
for Ti < 0.67T S
h
The minimum required cargo mass ( W min (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following
formulae:W min (Ti ) = 0

for Ti £ 0.83TS(Ti - 0.83TS )for TS ³ Ti > 0.83T S
hExample for mass curve of cargo hold for BC-B and BC-C ships is shown in Fig. 3.
Wmin (Ti ) = 1.025V H

Example of mass curve for BC-B and BC-C ships not having {No MP} assigned
1.15MFull
MFull

HarbourCargo mass

Fig. 30

0.15MFull

Seagoing
0.67TS 0.83TS TS Draught－132－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 1)

2.1.5 BC-B and BC-C ships having {No MP} assigned
The maximum permissible mass Wmax (Ti ) at various draughts Ti is obtained, in t, by the following formulae:
TS - Tih
The minimum required cargo mass ( Wmin (Ti ) ) at various draughts ( T i ) is obtained, in t, by the following
Wmax (Ti ) = M Full - 1.025VH

formulae:W min (Ti ) = 0
Wmin (Ti ) = 1.025V H

for Ti £ THB(Ti - THB )for TS ³ Ti > T HB orh

W min (Ti ) = 0 .5 M H - 1 .025V H(TS - Ti )hfor TS ³ Ti

Wmin(Ti ) ³ 0.0
Examples for mass curve of cargo hold for BC-B or BC-C ships with {No MP} are shown in Fig. 4.
Fig. 4

Example of mass curve for BC-B and BC-C ships with {No MP} assigned
1.15MFull
MFull

Cargo mass

Harbour

0.15MFull
0.5MH

Seagoing
THB 0.67TS

0TS Draught

2.2

Maximum permissible mass and minimum required masses of single cargo hold in harbour
condition
2.2.1 General
The cargo mass curves of single cargo hold in harbour condition are defined in 2.2.2. However if the ship structureis checked for more severe loading conditions than ones considered in Ch 4, Sec 7, 3.7.1, the minimum requiredcargo mass and the maximum allowable cargo mass can be based on those corresponding loading conditions.
2.2.2 All ships
The maximum permissible cargo mass and the minimum required cargo mass corresponding to draught for
loading/unloading conditions in harbour may be increased or decreased by 15% of the maximum permissible mass at
the maximum draught for the cargo hold in seagoing condition. However, maximum permissible mass is in no case to
be greater than the maximum permissible cargo mass at designed maximum load draught for each cargo hold.
2.2.3 BC-A ship not having {No MP} assigned
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) in harbour condition is also to be checked by
the following formulae in addition to the requirements in 2.1.2.
・ For loaded hold
Wmax (Ti ) = M HD
for Ti ³ 0.67TS
0.67TS - Ti
for Ti < 0.67TS
W max (Ti ) = M HD + 0 .1M H - 1 .025V H
h2.2.4 BC-A ship having {No MP} assigned
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) in harbour condition is also to be checked by
the following formulae in addition to the requirements in 2.1.3.
・ For empty hold which can be empty at the maximum draught
Wmax (Ti ) = M Fullfor TS ³ Ti ³ 0.67TS
W max (Ti ) = M Full - 1 . 025 V H

0 . 67 T S - Tihfor Ti < 0.67TS－133－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 1)

2.2.5 BC-B and BC-C ships having {No MP} assigned
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) in harbour condition is also to be checked by
the following formulae in addition to the requirements in 2.2.2.
Wmax (Ti ) = M Fullfor TS ³ Ti ³ 0.67TS
W max (T i ) = M Full - 1 . 025 V H

3.

0 . 67 T S - T ihfor Ti < 0 .67TS

Maximum and minimum masses of cargo of two adjacent holds

3.1

Maximum permissible mass and minimum required masses of two adjacent holds in seagoingcondition
3.1.1 General
The cargo mass curves of two adjacent cargo holds in seagoing condition are defined in 3.1.2 and 3.1.3. However
if the ship structure is checked for more severe loading conditions than ones considered in Ch 4, Sec 7, 3.7.1, theminimum required cargo mass and the maximum allowable cargo mass can be based on those corresponding loading
conditions.
3.1.2 BC-A ships with Block loading and not having {No MP} assigned
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) is obtained, in t, by the greater of the following
formulae:æ V f Va ö+
(Ts - Ti )W max (Ti ) = å ( M BLK + 0 .1M H ) - 1 .025 ç
ç hf
ha ø
è
æ V f Va ö+
(0.67Ts - Ti )Wmax (Ti ) = å M Full - 1.025ç
ç hf
ha ø
è
However, Wmax(Ti ) is no case to be greater thanΣMBLK.

or

The minimum required cargo mass ( Wmin (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following formulae:
W min ( T i ) = 0
for Ti £ 0.75TS
æVf V öWmin (Ti ) = 1.025ç + a (Ti - 0.75TS )for T S ³ T i > 0 . 75 T S
ç h f haèø
3.1.2 bis
BC-A ships with Block loading and having {No MP} assigned
The maximum permissible mass Wmax(Ti ) at various draughts Ti is obtained, in t, by the following formula:æ V f Va ö
Wmax (Ti ) = å ( M BLK + 0.1M H ) - 1.025ç
(Ts - Ti )+
ç h f haèøHowever, Wmax(Ti ) is no case to be greater than ΣMBLK.

The minimum required cargo mass Wmin(Ti ) at various draughts Ti is obtained, in t, by the following formulae:
Wmin (Ti ) = 0
for Ti £ THB
æVf V öWmin (Ti ) = 1.025ç + a (Ti - THB )for TS ³ Ti > THBç h f haèø
Examples for mass curve of cargo hold for BC-A with block loading ships are shown in Fig 5.

－134－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 1)

Fig. 5

Example of mass curve for BC-A ships with Block loading
S(MBLK+0.1MH )S(MBLK)
S(MFull)

0.15S(MBLK +0.1MH)

Seagoing
0.67TS 0.75TS

0HarbourCargo mass

Cargo mass

Harbour

S(MBLK+0.1MH )S(MBLK)TS Draught

0.15S(MBLK +0.1MH)

Seagoing0THB(a) without {No MP}

TS Draught(b) with {No MP}

3.1.3 (void)
3.1.4 BC-A ships without Block loading and BC-B, BC-C ships, not having {No MP} assigned
The maximum permissible mass ( Wmax (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following formulae:
Wmax (Ti ) = å M Fullfor TS ³ Ti ³ 0.67TS

æ V f Va ö+
(0.67TS - Ti )for Ti < 0.67TS
Wmax (Ti ) = å M Full - 1.025ç
ç h f haèøThe minimum required cargo mass ( Wmin (Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following formulae:
W min ( T i ) = 0
for T i £ 0 . 75 T S
æ V f Va ö+
Wmin (Ti ) = 1.025ç
(T - 0.75TS ) for T S ³ Ti > 0 . 75 T S
ç h f ha ièø
3.1.5 BC-A ships without Block loading and BC-B, BC-C ships, having {No MP} assigned
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following formula:æ V f Va ö+
(TS - Ti )for Ti < TS
Wmax (Ti ) = å M Full - 1.025ç
ç h f haèøThe minimum required cargo mass ( Wmin(Ti ) ) at various draughts ( Ti ) is obtained, in t, by the following formulae:
Wmin (Ti ) = 0
for Ti £ THB
æ V f Va ö+
(Ti - THB )for TS ³ Ti > THB
Wmin (Ti ) = 1.025ç
ç hf
ha ø
è
Examples for mass curve of cargo hold for BC-A without block loading and BC-B or BC-C are shown in Fig. 6.

Example of mass curve for BC-A ships without block loading and BC-B or BC-C ships
S(1.15MFull)
S(MFull)

Cargo mass

Harbour0

S(1.15MFull)
S(MFull)

HarbourCargo mass

Fig. 6

0.15S(MFull)

Seagoing

0.67TS 0.75TS

TS Draught

0(a) without {No MP}

0.15S(MFull)

Seagoing
THB 0.67TS(b) with {No MP}－135－

TS Draught

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 1)

3.2

Maximum permissible mass and minimum required masses of two adjacent cargo holds inharbour condition
3.2.1 General
The cargo mass curves of two adjacent cargo holds in harbour condition are defined in 3.2.2. However if the ship
structure is checked for more severe loading conditions than ones considered in Ch 4, Sec 7, 3.7.1, the minimum
required cargo mass and the maximum allowable cargo mass can be based on those corresponding loading
conditions.
3.2.2 All ships
The maximum permissible cargo mass and minimum required cargo mass corresponding to draught for
loading/unloading conditions in harbour may be increased or decreased by 15% of the maximum permissible mass at
the maximum draught for the cargo hold in seagoing condition. However, maximum permissible mass is in no case to
be greater than the maximum permissible cargo mass at designed maximum load draught for each cargo hold.
3.2.3 BC-A ships with Block loading and having {No MP} assigned
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) in harbour condition is also to be checked by
the following formulae in addition to the requirements in 3.1.2 bis:
æ V f Va ö+
(0.67TS - Ti )Wmax (Ti ) = å M Full - 1.025ç
ç h f haèø
Wmax (Ti ) = å M BLK
3.2.4 BC-A ships without Block loading and BC-B, BC-C ships, having {No MP} assigned
The maximum permissible mass ( Wmax(Ti ) ) at various draughts ( Ti ) in harbour condition is also to be checked by
the following formulae in addition to the requirements in 3.1.5:
Wmax (Ti ) = å M Fullfor TS ³ Ti ³ 0.67TS
æ V f Va ö+
(0.67TS - Ti )Wmax (Ti ) = å M Full - 1.025ç
ç h f ha
è
ø

－136－

for Ti < 0.67TS

Draught

TS

TS

TS

TS

THB

0.67TS

0.67TS

0.75TS

Description a)

Full Load([2.1.3])

Full Load([3.2.1])

Slack Load([3.2.2])

Slack Load([3.2.2])

Deepest Ballast([3.2.3])

Multi Port -3([3.3.3])

Multi Port -3([3.3.3])

Multi Port -4([3.3.4])

No.

1

2

3

4

5

6

7

8

Table 1

－137－

MFull

MFull

MFull

MFull

MFull

MFull

MFull

MFull

MH

MFull

50%MH

MFull

MFull

MH

Aft

Mid

Fore

MSW,H

F2

MSW,S

H1

MSW,S

H1

MSW,H

R1

0

P1

0

P1

0.5MSW,S

P1

0.5MSW,S

P1

MSW,S

P1

MSW,S

R1

MSW,S

P1

Still water vertical bending moment

Load Case (Design Wave)b)

Remarks

3), 6)

3), 6)

3), 6)

4), 5)

3)

3)1), 3)

1), 2)(see below)

Appendix 2

50%MH

MFull

MH

Loading Pattern

Bending moment analysis applicable to empty hold in alternate condition of BC-A (mid-hold is empty hold)2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

STANDARD LOADING CONDITION FOR DIRECT
STRENGTH ANALYSIS

0.75TS

TS

TS

TS

Multi Port -4([3.3.4])

Alternate Load([3.4.1])

Alt-Block Load([3.4.3])

Alt-Block Load([3.4.3])

9

10

11

12

THB(min)

0.67TS

0.67TS

Heavy Ballast([3.5.1])

Heavy Ballast

Harbour
Condition -2([3.6.2])

Harbour
Condition -2([3.6.2])

13

14

15

16

THB(min)Draught

Description a)

No.

MFull

MBLK+
0.1MH

MHD+
0.1MH

－138－
MFull

MFull

MBLK+
0.1MH

MBLK+
0.1MH

MFull

MBLK+
0.1MH

MHD+
0.1MH

MFull

Loading Pattern

Aft

Mid

Fore

MSW,P,S-----MSW,P,H

MSW,P,S-----MSW,P,H

MSW,S

R1

R1
0

0

R1

H1
MSW,S

MSW,H

F2

H1
MSW,S

MSW,H

F2

H1
MSW,S

0

P1

F2
MSW,H

MSW,S

MSW,H

P1

MSW,S

R1

MSW,S

P1

MSW,S

P1

3),14), 15)3),14), 15)11),12), 13)11),12)2), 8), 9), 10)2), 8), 9), 10)

2)3), 6)

Still water vertical bending moment b)
F2

Remarks(see below)

Load Case (Design Wave)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

MBLK is maximum cargo mass according to the design loading condition in the loading manual.

－139－

TS

THB(min)

Alternate Load([3.4.1])

Heavy Ballast([3.5.1])

10SF

13SF

MHD+
0.1MH

MHD+
0.1MH

b) MSW,H , MSW,S : Allowable still water vertical bending moment for seagoing condition, hogging or sagging respectively

QSW

0.8MSW,S

H1

QSW

0.8MSW,H

F2

Shear force analysis applicable to empty hold of BC-A (mid-hold is empty hold)
Load Case (Design Wave)
Loading Pattern
Aft
Mid
Fore
Still water vertical bending moment b)
Still water shear forcea) Referred paragraph number corresponds to loading pattern prescribed in Ch 4, Sec 7.

Draught

Description a)No.

Table 215) External sea pressures and internal pressures can be considered as static.

14) This condition is to be analyzed when {no MP} notation is assigned.

13) This condition is not required when such a condition is explicitly prohibited in the loading manual.

12) Minimum draught among heavy ballast conditions is to be used in principle.

11) This condition is to be considered for the empty hold which is assigned as ballast hold if any.

10) Actual still water vertical bending moment, as given in the loading manual, may be used in stead of design value.

9)8) This condition is only required when such a condition is prepared in the loading manual.

7) For vertical shear force analysis, maximum shear force (QSW + QWV) with reduced vertical bending moment (0.8MSW + 0.65CWVMWV) is to be considered.

6) This condition is not required when {no MP} notation is assigned.

5) Position of ballast hold is to be adjusted as appropriate.

4) In case of no ballast hold, normal ballast condition with assuming MSW,S = 0 is to be analyzed.

3) MH/VH or 1.0 t/m3, whichever is greater, is to be used as cargo density for calculation of dry cargo pressure.

2) Cargo density 3.0 t/m3 is to be used for calculation of dry cargo pressure in principle.

1) Single loading pattern in MFull with cargo density of 3.0 t/m3 can be analyzed in lieu of these two loading patterns.

Remarks

MSW,P,H, MSW,P,S : Allowable still water vertical bending moment for harbour condition, hogging or sagging respectivelyb) MSW,H, MSW,S : Allowable still water vertical bending moment for seagoing condition, hogging or sagging respectivelya) Referred paragraph number corresponds to loading pattern prescribed in Ch 4, Sec 7.

7), 11), 12)2), 7)

Remarks(see Table
1 above)2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

Draught

TS

TS

TS

THB

0.83TS

0.67TS

0.67TS

0.75TS

Description a)

Full Load([2.1.3])

Full Load([3.2.1])

Slack Load([3.2.2])

Deepest Ballast([3.2.3])

Multi Port -2([3.3.2])

Multi Port -3([3.3.3])

Multi Port -3([3.3.3])

Multi Port -4([3.3.4])

1

2

3

4

5

6

－140－

7

8

MFull

MFull

MFull

MFull

MFull

MH

MFull

MFull

50%MH

MFull

MH

MFull

MFull

MFull

MFull

MH

Loading Pattern

Aft

Mid

Fore

MSW,H

F2

MSW,S

P1

MSW,S

P1

MSW,H

R1

MSW,S

P1

F2
MSW,H

MSW,S

R1

MSW,H

R1

0

P1

0.5MSW,S

P1

0.5MSW,S

P1

MSW,S

R1

MSW,S

P1

b)

MSW,S

P1

Still water vertical bending moment

Load Case (Design Wave)

Bending moment analysis applicable to loaded hold in alternate condition of BC-A (mid-hold is loaded hold)No.

Table 33), 6)

3), 6)

3), 6)

3), 6)

4), 5)

3)1), 3)

1), 2)

Remarks(see below)
2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

0.75TS

TS

TS

TS

Multi Port -4([3.3.4])

Alternate Load([3.4.2])

Alt-Block Load([3.4.3])

Alt-Block Load([3.4.3])

9

10

11

12

THB(min)

0.67TS

0.67TS

0.67TS

Heavy Ballast([3.5.1])

Heavy Ballast

Harbour Condition -1([3.6.1])

Harbour Condition -1([3.6.1])

Harbour Condition -1([3.6.1])

13

14

15

16

17

THB(min)Draught

Description a)

No.

MFull

MBLK+
0.1MH

MHD

MBLK+
0.1MH

MBLK+
0.1MH

MHD+
0.1MH

MFull

MBLK+
0.1MH

MFull

Loading Pattern

Aft

Mid

Fore

－141－

MSW,P,S-----MSW,P,H

MSW,P,S-----MSW,P,H

MSW,P,S-----MSW,P,H

MSW,S

R1

R1
0

0

R1

MSW,S

H1

MSW,H

F2

H1
MSW,S

MSW,H

F2

H1
MSW,S

0

P1

F2
MSW,H

MSW,H

R1

MSW,H

F2

MSW,S

R1

MSW,S

P1

MSW,S

P1

MSW,S

R1
MSW,S

P1

Still water vertical bending moment b)

Load Case (Design Wave)

15)3), 14), 15)3), 14), 15)2),11), 12), 13)11),12)2), 8), 9), 10)2), 8), 9), 10)

2)3), 6)

Remarks(see below)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

0.67TS

0.67TS

Harbour Condition -2([3.6.2])

Harbour Condition -2([3.6.2])

18

19

MFull

MFull

MFull

MFull

Loading Pattern

Aft

Mid

Fore

－142－

MBLK is maximum cargo mass according to the design loading condition in the loading manual.

15) External sea pressures and internal pressures can be considered as static.

14) This condition is to be analyzed when {no MP} notation is assigned.

13) This condition is not required when such a condition is explicitly prohibited in the loading manual.

12) Minimum draught among heavy ballast conditions is to be used in principle.

11) This condition is to be considered for the loaded hold which is assigned as ballast hold if any.

10) Actual still water vertical bending moment, as given in the loading manual, may be used in stead of design value.

9)8) This condition is only required when such a condition is prepared in the loading manual.

7) For vertical shear force analysis, maximum shear force (QSW + QWV) with reduced vertical bending moment (0.8MSW + 0.65CWVMWV) is to be considered.

6) This condition is not required when {no MP} notation is assigned.

5) Position of ballast hold is to be adjusted as appropriate.

4) In case of no ballast hold, normal ballast condition with assuming MSW,S = 0 is to be analyzed.

3) MH/VH or 1.0 t/m3, whichever is greater, is to be used as cargo density for calculation of dry cargo pressure.

2) Cargo density 3.0 t/m3 is to be used for calculation of dry cargo pressure in principle.

1) Single loading pattern in MFull with cargo density of 3.0 t/m3 can be analyzed in lieu of these two loading patterns.

MSW,P,S-----MSW,P,H

MSW,P,S---

MSW,P,H---

MSW,P,H, MSW,P,S : Allowable still water vertical bending moment for harbour condition, hogging or sagging respectively

Remarks

Load Case (Design Wave)
Still water vertical bending moment b)b) MSW,H, MSW,S : Allowable still water vertical bending moment for seagoing condition, hogging or sagging respectivelya) Referred paragraph number corresponds to loading pattern prescribed in Ch 4, Sec 7.

Draught

Description a)

No.

3), 14), 15)3), 14), 15)

Remarks(see below)
2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

THB(min)Heavy Ballast([3.5.1])

10SF

13SF

MHD+
0.1MH

Loading Pattern

Aft

Fore

QSW

0.8MSW,S

H1

QSW

0.8MSW,H

F2

Still water shear force

Still water vertical bending moment b)b) MSW,H, MSW,S : Allowable still water vertical bending moment for seagoing condition, hogging or sagging respectively

Mid

Load Case (Design Wave)

Shear force analysis applicable to loaded hold of BC-A (mid-hold is loaded hold)a) Referred paragraph number corresponds to loading pattern prescribed in Ch 4, Sec 7.

TS

Alternate Load([3.4.2])

Draught

Description

No.

a)

Table 47), 11), 12)2), 7)

Remarks(see Table 3
above)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)－143－

Draught

TS

TS

TS

THB

0.83TS

0.67TS

0.67TS

0.75TS

Description a)

Full Load([2.1.3])

Full Load([3.2.1])

Slack Load([3.2.2])

Deepest Ballast([3.2.3])

Multi Port -2([3.3.2])

Multi Port -3([3.3.3])

Multi Port -3([3.3.3])

Multi Port -4([3.3.4])

No.

1

2

3

4

5

－144－

6

7

8

MFull

MFull

MFull

MFull

MFull

MH

MFull

MFull

50%MH

MFull

MH

MFull

MFull

MFull

MFull

MH

Aft

Mid

Fore

MSW,H

F2

MSW,S

P1

MSW,S

P1

MSW,H

R1

MSW,S

P1

F2
MSW,H

MSW,S

R1

MSW,H

R1

0

P1

0.5MSW,S

P1

0.5MSW,S

P1

MSW,S

R1

MSW,S

P1

b)

MSW,S

P1

MSW,H

F2

Still water vertical bending moment

Load Case (Design Wave)

Bending moment analysis applicable to BC-B and BC-C

Loading Pattern

Table 54), 7)

4), 7)

4), 7)

4), 7)

5), 6), 14)

4)2), 4)

1), 2), 3)

Remarks(see below)
2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

－145－

15

MFull

MFull

MFull

MFull

MFull

MFull

MFull

Loading Pattern

Aft

Mid

Fore

3) Cargo density 3.0 t/m3 is to be used for calculation of dry cargo pressure in principle.

2) For BC-B single loading pattern in MFull with cargo density of 3.0 t/m3 can be analyzed in lieu of these two loading patterns.

1) Applicable to BC-B only.

MS,P(-)-----MS,P(+)

MS,P(-)-----MS,P(+)

MS,P(-)-----MS,P(+)

MS,P(-)-----MS,P(+)

MSW,S

R1

R1
0

0

R1

H1
MSW,S

MSW,H

R1

MSW,H

F2

MSW,P,H, MSW,P,S : Allowable still water vertical bending moment for harbour condition, hogging or sagging respectively

Remarks

Load Case (Design Wave)

MSW,S

R1

MSW,S

R1
MSW,S

P1

Still water vertical bending moment b)b) MSW,H, MSW,S : Allowable still water vertical bending moment for seagoing condition, hogging or sagging respectivelya) Referred paragraph number corresponds to loading pattern prescribed in Ch 4, Sec 7.

0.67TS

Harbour
Condition -2([3.6.2])

14

12

0.67TS

0.67TS

Harbour
Condition -1([3.6.1])

11

Harbour
Condition -2([3.6.2])

THB(min)

Heavy Ballast

10

13

THB(min)

Heavy Ballast([3.5.1])

9

0.67TS

0.75TS

Multi Port -4([3.3.4])

Harbour
Condition -1([3.6.1])

Draught

Description a)

No.

4), 12), 13)4), 12), 13)4), 12), 13)4), 12),13)9), 10), 11)9), 10)4), 7)

Remarks(see below)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

－146－

THB(min)

Heavy Ballast([3.5.1])

10SF

MFull

MFull

QSW

0.8MSW,S

H1

QSW

0.8MSW,H

F2b) MSW,H, MSW,S : Allowable still water vertical bending moment for seagoing condition, hogging or sagging respectivelya) Referred paragraph number corresponds to loading pattern prescribed in Ch 4, Sec 7.

0.83TS

Draught

5SF

Description a)

Multi Port -2([3.3.2])

No.

Shear force analysis applicable to BC-B and BC-C
Load Case (Design Wave)
Loading Pattern
Aft
Mid
Fore
Still water vertical bending moment b)
Still water shear force

Table 6

14) Load case F2 is to be analyzed when {no MP} notation is assigned.

13) External sea pressures and internal pressures can be considered as static.

12) This condition is to be analyzed when {no MP} notation is assigned.

11) This condition is not required when such a condition is explicitly prohibited in the loading manual.

10) Minimum draught among heavy ballast conditions is to be used in principle.

9) This condition is to be considered for the cargo hold which is assigned as ballast hold if any.

8) For vertical shear force analysis, maximum shear force (QSW + QWV) with reduced vertical bending moment (0.8MSW + 0.65CWVMWV) is to be considered.

7) This condition is not required when {no MP} notation is assigned.

6) Position of ballast hold is to be adjusted as appropriate.

5) In case of no ballast hold, normal ballast condition with assuming MSW,S = 0 is to be analyzed.

4) MH/VH or 1.0 t/m3, whichever is greater, is to be used as cargo density for calculation of dry cargo pressure.

8), 9), 10)4), 7), 8)

Remarks(see Table 5
above)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 2)

Alternate Load

Normal Ballast

2

3

－147－

THB

TNB

T

T

a)

MHD

MH
MH

MHD

MH

Loading pattern

Aft

Mid

Fore

F2

H2

F2

H2
F1

F1

H1

H1

F2

F1

H1
H2

F2

F1

H1
H2

F2

F1

H2

H1

R2

R1

R2

R1

R2

R1

R2

R1

R2

R1

P2

P1

P2

P1

P2

P1

P2

P1

P2

P1

Load case (Design wave)

4) This condition is to be applied only for the empty hold which is assigned as ballast hold.

MS,(4)

MS,(4)

MS,(3)

MS,(2)

MS,(1)

Still watervertical bendingb)
moment3) This condition is to be applied only for the empty hold which is not assigned as ballast hold. Position of ballast hold is to be adjusted as appropriate.

2) Cargo density 3.0 t/m3 is to be used for calculation of dry cargo pressure in principle.

1) MH/VH is to be used as cargo density for calculation of dry cargo pressure.

Remarksb) MS,(1), MS,(2), MS,(3), MS,(4) : Still water vertical bending moment as defined in 3.2.2 of Ch 8, Sec 3a) T : Moulded draught, TNB : Draught at normal ballast condition, THB : Draught at heavy ballast condition

Heavy Ballast

Full Load

1

Draught

Fatigue Assessment applicable to empty hold in alternate condition of BC-A (mid-hold is empty hold)

4)

3)

2)

1)

Remarks(see
below)

Appendix 3

4

Description

No.

Table 12015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 3)

STANDARD LOADING CONDITION FOR
FATIGUE ASSESSMENT

Alternate Load

Normal Ballast

2

3

－148－

THB

TNB

T

T

Draught

a)

MH

MHD

MH

MH

Loading pattern

Aft

Mid

Fore

R2

R1

R2

R1

R2

R1

R2

R1

R2

R1

P2

P1

P2

P1

P2

P1

P2

P1

P2

P1

4) This condition is to be applied only for the empty hold which is assigned as ballast hold.

MS,(4)

MS,(4)

MS,(3)

MS,(2)

MS,(1)

Still watervertical bendingb)
moment3) This condition is to be applied only for the empty hold which is not assigned as ballast hold. Position of ballast hold is to be adjusted as appropriate.

2) Cargo density 3.0 t/m3 is to be used for calculation of dry cargo pressure in principle.

1) MH/VH is to be used as cargo density for calculation of dry cargo pressure.

Remarksb) MS,(1), MS,(2), MS,(3), MS,(4) : Still water vertical bending moment as defined in 3.2.2 of Ch 8, Sec 3

F2

H2

F2

H2
F1

F1

H1

H1

F2

F1

H1
H2

F2

F1

H1
H2

F2

F1

H2

H1

Load case (Design wave)

Fatigue Assessment applicable to loaded hold in alternate condition of BC-A (mid-hold is loaded hold)a) T : Moulded draught, TNB : Draught at normal ballast condition, THB : Draught at heavy ballast condition

Heavy Ballast

Full Load

1

4

Description

No.

Table 2

4)

3)

2)

1)

Remarks(see
below)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 3)

Full Load

Normal Ballast

Heavy Ballast

1

2

3

THB

TNB

T

Draught

a)

MH
MH

MH

Loading pattern

Aft

Mid

Fore

－149－

R2

R1

R2

R1

R2

R1

R2

R1

P2

P1

P2

P1

P2

P1

P2

P1

3) This condition is to be applied only for the empty hold which is assigned as ballast hold.

MS,(4)

MS,(4)

MS,(3)

MS,(1)

Still watervertical bendingb)
moment2) This condition is to be applied only for the empty hold which is not assigned as ballast hold. Position of ballast hold is to be adjusted as appropriate.

1) MH/VH is to be used as cargo density for calculation of dry cargo pressure.

Remarksb) MS,(1), MS,(2), MS,(3), MS,(4) : Still water vertical bending moment as defined in 3.2.2 of Ch 8, Sec 3

F2

H2

F2

H2
F1

F1

H1

H1

F2

F1

H1
H2

F2

F1

H2

H1

Load case (Design wave)

Fatigue Assessment applicable to BC-B, BC-Ca) T : Moulded draught, TNB : Draught at normal ballast condition, THB : Draught at heavy ballast condition

Description

No.

Table 3

3)

2)

1)

Remarks(see
below)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 4 Appendix 3)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Section 1)

Chapter 5
Section 1

HULL GIRDER STRENGTHYIELDING CHECK

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
MSW : Design still water bending moment in intact condition, in kN-m, at the hull transverse section considered,defined in Ch 4, Sec 3, 2.2:
in hogging conditions
MSW = MSW,Hin sagging conditions
MSW = MSW,S
MWV : Vertical wave bending moment in intact condition, in kN-m, at the hull transverse section considered,defined in Ch 4, Sec 3, 3.1
MSW,F : Still water bending moment, in kN-m, in flooded conditions, at the hull transverse section underconsideration, to be calculated according to Ch 4, Sec 3
MWV,F : Vertical wave bending moment, in kN-m, in flooded conditions, at the hull transverse section underconsideration, , to be calculated according to Ch 4, Sec 3
MWV,P : Vertical wave bending moment, in kN-m, in harbour conditions, at the hull transverse section underconsideration, to be calculated according to Ch 4, Sec 3
MWH : Horizontal wave bending moment, in kN-m, at the hull transverse section considered, defined in Ch 4, Sec 3,
3.3
QSW : Design still water shear force in intact condition, in kN, at the hull transverse section considered, defined in
Ch 4, Sec 3, 2.3
QWV : Vertical wave shear force in intact condition, in kN, at the hull transverse section considered, defined in Ch
4, Sec 3, 3.2
QSW,F : Still water shear force, in kN, in flooded conditions, at the hull transverse section under consideration, to be
calculated according to Ch 4, Sec 3
QWV,F : Vertical wave shear force, in kN, in flooded conditions, at the hull transverse section under consideration, tobe calculated according to Ch 4, Sec 3
QWV,P : Vertical wave shear force, in kN, in harbour conditions, at the hull transverse section under consideration, tobe calculated according to Ch 4, Sec 3k: Material factor, as defined in Ch 1, Sec 4, 2.2.1
x: X co-ordinate, in m, of the calculation point with respect to the reference co-ordinate system defined in Ch 1,
Sec 4, 4z: Z co-ordinate, in m, of the calculation point with respect to the reference co-ordinate system defined in Ch 1,
Sec 4, 4N: Z co-ordinate, in m, of the centre of gravity of the hull transverse section defined in 1.2, with respect to thereference co-ordinate system defined in Ch 1, Sec 4, 4
: Vertical distance, in m, defined in 1.4.2
VD: Net moment of inertia, in m4, of the hull transverse section about its horizontal neutral axis, to be calculated
IY
according to 1.5: Net moment of inertia, in m4, of the hull transverse section about its vertical neutral axis, to be calculated
IZ
according to 1.5
S: Net first moment, in m3, of the hull transverse section, to be calculated according to 1.6: Net section modulus, in m3, at any point of the hull transverse section, to be calculated according 1.4.1
ZA
ZAB, ZAD : Net section moduli, in m3, at bottom and deck, respectively, to be calculated according to 1.4.2
C: Wave parameter defined in Ch 1, Sec 4, 2.3.1
s1,ALL : Allowable normal stress, in N/mm2, defined in 3.1.1
t1,ALL : Allowable shear stress, in N/mm2, defined in 3.2.1
r: Sea water density, taken equal to 1.025 t/m3.

－150－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Section 1)

1.

Strength characteristics of the hull girder transverse sections

1.1
General1.1.1This Article specifies the criteria for calculating the hull girder strength characteristics to be used for the checks in
2 to 5, in association with the hull girder loads specified in Ch 4, Sec 3.
1.2
Hull girder transverse sections
1.2.1 General
Hull girder transverse sections are to be considered as being constituted by the members contributing to the hull
girder longitudinal strength, i.e. all continuous longitudinal members below and including the strength deck definedin 1.3, taking into account the requirements in 1.2.2 to 1.2.9.
These members are to be considered as having (see also Ch 3, Sec 2) net offered scantlings based on gross offered
thickness reduced by 0.5tC, when the hull girder strength characteristics are used for:・ the hull girder yielding check according to 2 to 5
・ the ultimate strength check in Ch 5, Sec 2・ the calculation of the hull girder stresses for the strength checks of plating, ordinary stiffeners and primary
supporting members according to Ch 6.
1.2.2 Continuous trunks and continuous longitudinal hatch coamings
Continuous trunks and continuous longitudinal hatch coamings may be included in the hull girder transverse
sections, provided they are effectively supported by longitudinal bulkheads or primary supporting members.
1.2.3 Longitudinal ordinary stiffeners or girders welded above the strength deck
Longitudinal ordinary stiffeners or girders welded above the strength deck (including the deck of any trunk fitted
as specified in 1.2.2) are to be included in the hull girder transverse sections.
1.2.4 Longitudinal girders between hatchways, supported by longitudinal bulkheads
Where longitudinal girders, effectively supported by longitudinal bulkheads, are fitted between hatchways, thesectional area of these longitudinal girders are to be included in the hull girder transverse.
1.2.5 Longitudinal bulkheads with vertical corrugations
Longitudinal bulkheads with vertical corrugations are not to be included in the hull girder transverse sections.
1.2.6 Members in materials other than steel
Where a member contributing to the longitudinal strength is made in material other than steel with a Young s
modulus E equal to 2.06・105 N/mm2, the steel equivalent sectional area that may be included in the hull girdertransverse sections is obtained, in m2, from the following formula:
E
ASE =
AM
2.06 10 5
where:
AM : Sectional area, in m2, of the member under consideration.
1.2.7 Large openings
Large openings are:・ elliptical openings exceeding 2.5 m in length or 1.2 m in breadth・ circular openings exceeding 0.9 m in diameter.
Large openings and scallops, where scallop welding is applied, are always to be deducted from the sectional areas
included in the hull girder transverse sections.
1.2.8 Small openings
Smaller openings than those in 1.2.7 in one transverse section in the strength deck or bottom area need not be
deducted from the sectional areas included in the hull girder transverse sections, provided that:
Sb S £ 0.06(B - Sb )where:
SbS : Total breadth of small openings, in m, in the strength deck or bottom area at the transverse section
considered, determined as indicated in Fig. 1－151－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Section 1)

Sb : Total breadth of large openings, in m, at the transverse section considered, determined as indicated inFig. 1.
Where the total breadth of small openings SbS does not fulfil the above criteria, only the excess of breadth is to be
deducted from the sectional areas included in the hull girder transverse sections.
1.2.9 Lightening holes, draining holes and single scallops
Lightening holes, draining holes and single scallops in longitudinals need not be deducted if their height is lessthan 0.25hw , without being greater than 75 mm, where hw is the web height, in mm.
Otherwise, the excess is to be deducted from the sectional area or compensated.
Fig. 1

Calculation of Sb and SbS

b1

30°

Hull transverse section
under consideration

30°

b2

b1 and b2 included in Σb and Σbs

1.3
Strength deck
1.3.1
The strength deck is, in general, the uppermost continuous deck.
In the case of a superstructure or deckhouses contributing to the longitudinal strength, the strength deck is the deckof the superstructure or the deck of the uppermost deckhouse.
1.3.2
A superstructure extending at least 0.15LCSR-B within 0.4LCSR-B amidships may generally be considered ascontributing to the longitudinal strength.
For other superstructures and for deckhouses, their contribution to the longitudinal strength is to be assessed on acase by case basis, to evaluate their percentage of participation to the longitudinal strength.
1.4
Section modulus
1.4.1
The section modulus at any point of a hull transverse section is obtained, in m3, from the following formula:
IY
ZA =
z-N
1.4.2
The section moduli at bottom and at deck are obtained, in m3, from the following formulae:
・ at bottom:
I
Z AB = YN・ at deck:I
Z AD = Y
VD
where:－152－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Section 1)

VD : Vertical distance, in m, taken equal to:・ in general:
VD = z D - N
where:
zD : Z co-ordinate, in m, of strength deck at side, defined in 1.3, with respect to the reference co-ordinate
system defined in Ch 1, Sec 4, 4・ if continuous trunks or hatch coamings are taken into account in the calculation of IY , as specified in 1.2.2:y öæV D = ( z T - N )çç 0.9 + 0.2 T ³ z D - N
B øèwhere:
yT, zT : Y and Z co-ordinates, in m, of the top of continuous trunk or hatch coaming with respect to thereference co-ordinate system defined in Ch 1, Sec 4, 4; yT and zT are to be measured for the point
which maximises the value of VD
・ if longitudinal ordinary stiffeners or girders welded above the strength deck are taken into account in thecalculation of IY , as specified in 1.2.3, VD is to be obtained from the formula given above for continuous trunks
and hatch coamings. In this case, yT and zT are the Y and Z co-ordinates, in m, of the top of the longitudinal
stiffeners or girders with respect to the reference co-ordinate system defined in Ch 1, Sec 4, 4.
1.5
Moments of inertia
1.5.1
The moments of inertia IY and IZ , in m4, are those, calculated about the horizontal and vertical neutral axes,
respectively, of the hull transverse sections defined in 1.2.
1.6
First moment
1.6.1
The first moment S, in m3, at a level z above the baseline is that, calculated with respect to the horizontal neutral
axis, of the portion of the hull transverse sections defined in 1.2 located above the z level.
2.

Hull girder stresses

2.1
Normal stresses
2.1.1 General
The normal stresses in a member made in material other than steel with a Young s modulus E equal to 2.06・105
N/mm2, included in the hull girder transverse sections as specified in 1.2.6, are obtained from the following formula:
E
s1 =
s 1S
2.06 10 5
where:
s1S : Normal stress, in N/mm2, in the member under consideration, calculated according to 2.1.2 and 2.1.3
considering this member as having the steel equivalent sectional area ASE defined in 1.2.6.
2.1.2 Normal stresses induced by vertical bending moments
The normal stresses induced by vertical bending moments are obtained, in N/mm2, from the following formulae:
・ at any point of the hull transverse section, located below zVD , where zVD = VD + N:
M + M WV -3
s 1 = SW
10
ZA
・ at bottom:
M + M WV -3
s 1 = SW
10Z AB
・ at deck:s1 =M SW + M WV -3
10
Z AD

2.1.3 Normal stresses in flooded conditions of BC-A or BC-B ships
This requirement applies to BC-A or BC-B ships, in addition to 2.1.2.

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The normal stresses, in the flooded conditions specified in Ch 4, Sec 3, are to be obtained at any point, in N/mm2,
from the following formula:M+ M WV , F -3
s 1 = SW , F
10
ZA
2.2
Shear stresses
2.2.1 General
The shear stresses induced by vertical shear forces QSW and QWV in intact condition and, for BC-A and BC-B ships
by vertical shear forces QSW,F and QWV,F in flooded condition are normally to be obtained through direct analyses.
When they are combined, vertical shear forces QSW and QWV in intact condition are to be taken with the same sign.
The same is to be applied also for combination of vertical shear forces QSW,F and QWV,F in flooded condition.
The shear force correction DQC is to be taken into account, in accordance with 2.2.2. The shear force correctionneed not to be considered at the fore end of foremost hold and aft end of aftermost hold.
As an alternative to this procedure, the shear stresses induced by the vertical shear forces QSW and QWV in intact
condition and, for BC-A and BC-B ships by the vertical shear forces QSW,F and QWV,F in flooded condition may beobtained through the simplified procedure in 2.2.2 and 2.2.3 respectively.
2.2.2 Simplified calculation of shear stresses induced by vertical shear forces
The shear stresses induced by the vertical shear forces in the calculation point are obtained, in N/mm2, from thefollowing formula:St 1 = (Q SW + QWV - eDQC )d
IY t
where:t: Minimum net thickness, in mm, of side and inner side plating, as applicable according to Table 1d: Shear distribution coefficient defined in Table 1
e = sgn (Q SW )DQC : Shear force correction (see Fig. 2) at the section considered. The shear force correction is to beconsidered independently forward and aft of the transverse bulkhead for the hold considered. The
shear force correction takes into account, when applicable, the portion of loads transmitted by the
double bottom girders to the transverse bulkheads:
・ for ships with any non-homogeneous loading conditions, such as alternate hold loading conditions and heavy
ballast conditions carrying ballast in hold(s):DQC = aM
- rTLC ,mh for each non-homogeneous loading condition
BH l H・ for other ships and homogeneous loading conditions:
DQC = 0l 0 b0
a=g
l
2+j 0
b0

j = 1.38 + 1.55

l0
, to be taken not greater than 3.7
b0

l0, b0 : Length and breadth, respectively, in m, of the flat portion of the double bottom in way of the holdconsidered; b0 is to be measured on the hull transverse section at the middle of the holdlH : Length, in m, of the hold considered, measured between the middle of the transverse corrugatedbulkheads depth
BH : Ship s breadth, in m, measured at the level of inner bottom on the hull transverse section at the
middle of the hold considered
M : Mass, in t, in the considered section.
· Adjacent cargo hold is loaded for the non homogeneous loading condition for the condition underconsideration
M is to include the total mass in the hold and the mass of water ballast in double bottom tank,bounded by side girders in way of hopper tank plating or longitudinal bulkhead.
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M is the total mass in the hold.
TLC,mh: Draught, in m, measured vertically on the hull transverse section at the middle of the hold considered,from the moulded baseline to the waterline in the loading condition considered.

Shear force correction DQC

Fig. 2

Bulkhead

DQC_F

Full hold

Bulkhead
Empty hold

DQC_E

Corrected
Shear force

Bulkhead

Shear force obtained asSpecified in Ch 4, Sec 3

Note:
DQC_F: shear force correction for the full hold.
DQC_E: shear force correction for the empty hold.

Table 1

Shear stresses induced by vertical shear forces

Ship typology

Locationt, in mmd

Single side skin construction

Sides

tS

0.5

Sides

tS

0.5(1 - f )Inner sides

tIS

0.5f

Double side skin construction
where:
tS, tIS: Minimum net thicknesses, in mm, of side and inner side, respectivelytSM, tISM : Mean net thicknesses, in mm, over all the strakes of side and inner side , respectively. They are calculated as S(li ti) /fSli, where li and ti are the length, in m, and the net thickness, in mm, of the i th strake of side and inner side.
t: Coefficient taken equal to: f = 0.275 + 0.25 ISM
t SM

2.2.3 Shear stresses in flooded conditions of BC-A or BC-B ships
This requirement applies to BC-A or BC-B ships, in addition to 2.2.1 and 2.2.2.
The shear stresses, in the flooded conditions specified in Ch 4, Sec 3, are to be obtained at the calculation point, in
N/mm2, from the following formula:St 1 = (Q SW , F + QWV , F - eDQC )d
IYt
e = sgn (Q SW ,F )DQC : Shear force correction, to be calculated according to 2.2.2, where the mass of the ingressed water is tobe added to M and where the draught TLC,mh is to be measured up to the equilibrium waterlinet: Net thickness, in mm, of the side plating.

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3.

Checking criteria

3.1
Normal stresses
3.1.1
It is to be checked that the normal stresses s1 calculated according to 2.1.2 and, when applicable, 2.1.3 are incompliance with the following formula:s1 £ s1,ALL
where:
s1,ALL : Allowable normal stress, in N/mm2, obtained from the following formulae:
130xs1, ALL =for£ 0 .1LCSR -Bk2

s 1, ALL =ö
190 1500 æ x
ç
- 0 .3çkk è LCSR -B
ø

s1, ALL =190x
for 0.3 ££ 0.7
LCSR -Bks 1, ALL =ö
190 1500 æ x
ç
- 0.7
ç
k
k è LCSR -B
ø

s1, ALL =

130
x
for
³ 0 .9LCSR -Bk

for 0.1 <x
LCSR- B2

for 0.7 << 0 .3x< 0.9
LCSR -B

3.2
Shear stresses
3.2.1
It is to be checked that the shear stresses t1 calculated according to 2.2.1 or 2.2.2 and, when applicable, 2.2.3 are incompliance with the following formula:t1 £ t1,ALL
where:
t1,ALL : Allowable shear stress, in N/mm2:
t1,ALL = 120/k
4.

Section modulus and moment of inertia

4.1
General
4.1.1
The requirements in 4.2 to 4.5 provide the minimum hull net girder section modulus, complying with the checking
criteria indicated in 3, and the midship net section moment of inertia required to ensure sufficient hull girder rigidity.
4.1.2
The k material factors are to be defined with respect to the materials used for the bottom and deck members
contributing to the longitudinal strength according to 1. When material factors for higher strength steels are used, therequirements in 4.5 apply.
4.2
Section modulus within 0.4LCSR-B amidships
4.2.1
The net section moduli ZAB and ZAD at the midship section are to be not less than the value obtained, in m3, fromthe following formula:・ ZR,MIN = 0.9CLCSR-B2B(CB + 0.7)k10-6
4.2.2
In addition, the net section moduli ZAB and ZAD within 0.4LCSR-B amidships are to be not less than the value obtained,
in m3, from the following formula:
M + M WV
10 - 3
・ Z R = SW
s 1, ALL

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・ in addition, for BC-A and BC-B ships:
M SW , F + M WV , F - 3
ZR =10
s 1, ALL
4.2.3
Where the total breadth SbS of small openings, as defined in 1.2.8, is deducted from the sectional areas included in
the hull girder transverse sections, the values ZR,MIN and ZR defined in 4.2.1 or 4.2.2 may be reduced by 3%.
4.2.4
Scantlings of members contributing to the longitudinal strength (see 1), based on the section modulus requirementin 4.2.1, are to be maintained within 0.4LCSR-B amidships.
4.3
Section modulus outside 0.4LCSR-B amidships
4.3.1
The net section moduli ZAB and ZAD outside 0.4LCSR-B amidships are to be not less than the value obtained, in m3,
from the following formula:
M + M WV・ Z R = SW
10 - 3s 1, ALL・ in addition, for BC-A and BC-B ships:
M SW , F + M WV , F - 3
ZR =10
s 1, ALL
4.3.2
Scantlings of members contributing to the hull girder longitudinal strength (see 1) may be gradually reduced,
outside 0.4LCSR-B amidships, to the minimum required for local strength purposes at fore and aft parts, as specified in
Ch 9, Sec 1 or Ch 9, Sec 2, respectively.
4.4
Midship section moment of inertia
4.4.1
The net midship section moment of inertia about its horizontal neutral axis is to be not less than the value obtained,
in m4, from the following formula:
IYR = 3Z R' , MIN LCSR - B10-2
where Z R,MIN is the required net midship section modulus ZR,MIN, in m3, calculated as specified in 4.2.1, but
assuming k = 1.
4.5
Extent of higher strength steel
4.5.1
When a material factor for higher strength steel is used in calculating the required section modulus at bottom ordeck according to 4.2 or 4.3, the relevant higher strength steel is to be adopted for all members contributing to thelongitudinal strength (see 1), at least up to a vertical distance, in m, obtained from the following formulae:
・ above the baseline (for section modulus at bottom):s 1B - ks 1, ALL
V HB =zD
s 1B + s 1 D・ below a horizontal line located at a distance VD (see 1.4.2) above the neutral axis of the hull transverse section(for section modulus at deck):s 1D - k s 1, ALL
V HD =(N + V D )s 1B + s 1D
where:
s1B, s1D : Normal stresses, in N/mm2, at bottom and deck, respectively, calculated according to 2.1: Z co-ordinate, in m, of the strength deck defined in 1.3, with respect to the reference co-ordinatezD
system defined in Ch 1, Sec 4, 4
4.5.2
The higher strength steel is to extend in length at least throughout 0.4LCSR-B amidships where it is required forstrength purposes according to the provision of this Part.

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5.

Permissible still water bending moment and shear force

5.1
Permissible still water bending moment and shear force in intact condition
5.1.1 Permissible still water bending moment
The permissible still water bending moment at any hull transverse section in intact condition, in hogging or
sagging conditions, is the value MSW considered in the hull girder section modulus calculation according to 4.2 and4.3.
In the case of structural discontinuities in the hull transverse sections, the distribution of permissible still water
bending moments is considered on a case by case basis.
5.1.2 Permissible still water shear force - Direct calculation
Where the shear stresses are obtained through calculation analyses according to 2.2.1, the permissible positive or
negative still water shear force in intact condition at any hull transverse section is obtained, in kN, from the following
formula:Q P = e QT - QWV
where:
e = sgn (Q SW )QT : Shear force, in kN, which produces a shear stress t = 120/k N/mm2 in the most stressed point of the hullnet transverse section, taking into account the shear force correction DQC in accordance with 2.2.2.
A lower value of the permissible still water shear force may be considered, if requested by the Shipbuilder.
5.1.3 Permissible still water shear force - Simplified calculation
Where the shear stresses are obtained through the simplified procedure in 2.2.2, the permissible positive or
negative still water shear force in intact condition at any hull transverse section is obtained, in kN, from the following
formula:æ 120 I Y tö
Q P = e çç
+ DQC - QWVè kd Sø
where:
e = sgn (Q SW )d
: Shear distribution coefficient defined in Table 1t: Minimum net thickness, in mm, of side and inner side plating, as applicable according to Table 1
DQC : Shear force corrections defined in 2.2.2, to be considered independently forward and aft of thetransverse bulkhead.
A lower value of the permissible still water shear force may be considered, if requested by the Shipbuilder.
5.2
Permissible still water bending moment and shear force in harbour conditions
5.2.1 Permissible still water bending moment
The permissible still water bending moment at any hull transverse section in harbour conditions, in hogging or
sagging conditions, is obtained, in kN-m, from the following formula:
M P , P = M SW + M WV - M WV , P
A lower value of the permissible still water bending moment in harbour conditions may be considered, if requestedby the Shipbuilder.
5.2.2 Permissible still water shear force
The permissible positive or negative still water shear force at any hull transverse section, in harbour conditions, isobtained, in kN, from the following formula:Q P , P = eQ P + QWV - QWV , P
where:
e = sgn (Q SW )QP : Permissible still water shear force during navigation, in kN, to be calculated according to 5.1.3.
A lower value of the permissible still water shear force in harbour conditions may be considered, if requested by
the Shipbuilder.

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5.3
Permissible still water bending moment and shear force in flooded condition
5.3.1 Permissible still water bending moment
The permissible still water bending moment at any hull transverse section in flooded condition, in hogging or
sagging conditions, is the value MSW,F considered in the hull girder section modulus calculation according to 4.2 and4.3.
In the case of structural discontinuities in the hull transverse sections, the distribution of permissible still water
bending moments is considered on a case by case basis.
5.3.2 Permissible still water shear force - Direct calculation
Where the shear stresses are obtained through calculation analyses according to 2.2.1, the permissible positive or
negative still water shear force in flooded condition at any hull transverse section is obtained, in kN, from thefollowing formula:Q P , F = e QT - QWV , F
where:
e = sgn (Q SW , F )QT : Shear force, in kN, which produces a shear stress t = 120/k N/mm2 in the most stressed point of the hullnet transverse section, taking into account the shear force correction DQC in accordance with 2.2.2.
5.3.3 Permissible still water shear force - Simplified calculation
Where the shear stresses are obtained through the simplified procedure in 2.2.2, the permissible positive or
negative still water shear force in flooded condition at any hull transverse section is obtained, in kN, from thefollowing formula:æ 120 I Y tö
Q P , F = e çç
+ DQC - QWV , F
k
d
S
è
ø
where:
e = sgn (Q SW )d

: Shear distribution coefficient defined in Table 1: Minimum net thickness, in mm, of side and inner side plating, as applicable according to Table 1
DQC : Shear force correction, to be calculated according to 2.2.2, where the mass M is to include the mass of
the ingressed water in the hold considered and the draught TLC is to be measured up to the equilibrium
waterline.

t

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Section 2
1.

ULTIMATE STRENGTH CHECK

Application

1.1
General1.1.1
The requirements of this Section apply to ships equal to or greater than 150 m in length (LCSR-B).
2.

Hull girder ultimate strength check

2.1
Hull girder loads
2.1.1 Bending moment
The bending moment M in sagging and hogging conditions, to be considered in the ultimate strength check of thehull girder, is to be obtained, in kN-m, in intact, flooded and harbour conditions, from the following formula:
M = MSW + gW MWV
where:
MSW, MSW,F, MSW,P : Design still water bending moment, in kN-m, in sagging and hogging conditions at thehull transverse section considered, to be calculated respectively in intact (MSW), flooded(MSW,F) and harbour (MSW,P) conditions
MWV, MWV,F, MWV,P : Vertical wave bending moment, in kN-m, in sagging and hogging conditions at the hulltransverse section considered, defined in Ch 4, Sec 3, respectively in intact (MWV),
flooded (MWV,F) and harbour (MWV,P) conditions
gW : Safety factor on wave hull girder bending moments, taken equal to:gW = 1.20
2.2
Hull girder bending moment
2.2.1 Curve MThe ultimate bending moment capacities of a hull girder transverse section, in hogging and sagging conditions, aredefined as the maximum values of the curve of bending moment capacity M versus the curvature of the transverse
section considered (see Fig. 1).
The curvature is positive for hogging condition and negative for sagging condition.
The curve M- is to be obtained through an incremental-iterative procedure, according to the criteria specified in
App 1.
Fig. 1Curve bending moment capacity M versus curvature

2.2.2 Hull girder transverse sections
The hull girder transverse sections are constituted by the elements contributing to the hull girder longitudinalstrength, considered with their net offered scantlings according to Ch 3, Sec 2, 3.2.4.
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2.3
Checking criteria
2.3.1
It is to be checked that the hull girder ultimate bending capacity at any hull transverse section is in compliance withthe following formula:
M
M£ U
gR
where:
MU : Ultimate bending moment capacity of the hull transverse section considered, calculated with net
offered scantlings based on gross offered thickness reduced by 0.5tC, in kN-m:
in hogging conditions
MU = MUH
in sagging conditions
MU = MUSMUH : Ultimate bending moment capacity in hogging conditions, in kN-m, defined in 2.2.1
MUS : Ultimate bending moment capacity in sagging conditions, in kN-m, defined in 2.2.1
M : Bending moment, in kN-m, defined in 2.1.1 for the ship in intact, flooded and harbour conditions
gR : Safety factor taken equal to 1.10

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Appendix 1

HULL GIRDER ULTIMATE STRENGTH

Symbols
For symbols not defined in this Appendix, refer to Ch 1, Sec 4.
: Moment of inertia, in m4, of the hull transverse section around its horizontal neutral axis, to be calculated
according to Ch 5, Sec 1, 1.5.1
ZAB, ZAD : Section moduli, in m3, at bottom and deck, respectively, defined in Ch 5, Sec 1, 1.4.2.
: Minimum yield stress, in N/mm2, of the material of the considered stiffener.
ReHs: Minimum yield stress, in N/mm2, of the material of the considered plate.
ReHp: Net sectional area, in cm2, of stiffener, without attached plating.
AS: Net sectional area, in cm2, of attached plating.
AP
IY

1.

Hull girder ultimate strength check

1.1
Introduction
1.1.1
This Appendix provides the criteria for obtaining the curve M- and the ultimate longitudinal bending moment
capacity MU that are to be calculated according to the simplified incremental-iterative approach, as specified in 2.1.
2.

Criteria for the calculation of the curve M-

2.1
Simplified method based on a incremental-iterative approach
2.1.1 Procedure
The curve M- is to be obtained by means of an incremental-iterative approach, summarised in the flow chart in
Fig. 1.
In this approach, the ultimate hull girder bending moment capacity MU is defined as the peak value of the curvewith vertical bending moment M versus the curvature of the ship cross section as shown in Fig. 1. The curve is tobe obtained through an incremental-iterative approach.
Each step of the incremental procedure is represented by the calculation of the bending moment Mi which acts on
the hull transverse section as the effect of an imposed curvature i.
For each step, the value i is to be obtained by summing an increment of curvature D to the value relevant to theprevious step i-1.This increment of curvature corresponds to an increment of the rotation angle of the hull girdertransverse section around its horizontal neutral axis.
This rotation increment induces axial strains in each hull structural element, whose value depends on the positionof the element. In hogging condition, the structural elements above the neutral axis are lengthened, while theelements below the neutral axis are shortened. Vice-versa in sagging condition.
The stress induced in each structural element by the strain is to be obtained from the load-end shortening curve- of the element, which takes into account the behaviour of the element in the non-linear elasto-plastic domain.
The distribution of the stresses induced in all the elements composing the hull transverse section determines, foreach step, a variation of the neutral axis position, since the relationship - is non-linear. The new position of theneutral axis relevant to the step considered is to be obtained by means of an iterative process, imposing theequilibrium among the stresses acting in all the hull elements.
Once the position of the neutral axis is known and the relevant stress distribution in the section structural elements
is obtained, the bending moment of the section Mi around the new position of the neutral axis, which corresponds tothe curvature i imposed in the step considered, is to be obtained by summing the contribution given by each element
stress.
The main steps of the incremental-iterative approach described above are summarised as follows (see also Fig. 1):
Step 1 Divide the transverse section of hull into stiffened plate elements－162－

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Step 2 Define stress-strain relationships for all elements as shown in Table 1
Step 3 Initialize curvature c1 and neutral axis for the first incremental step with the value of incremental curvature(curvature that induces a stress equal to 1% of yield strength in strength deck) as:
R
0.01 eHE
c1 = D c =zD - N
where:
Z co-ordinate, in m, of strength deck at side, with respect to reference co-ordinate defined in Ch 1,zD :Sec 4, 4
Step 4 Calculate for each element the corresponding strain e i = c (z i - z NA ) and the corresponding stress si
Step 5 Determine the neutral axis zNA_cur at each incremental step by establishing force equilibrium over the wholetransverse section as:
SAi si = SAj sj (i-th element is under compression, j-th element under tension)
Step 6 Calculate the corresponding moment by summing the contributions of all elements as:
M U = å s Ui Ai z i - z NA _ cur()

Step 7 Compare the moment in the current incremental step with the moment in the previous incremental step. If theslope in M- relationship is less than a negative fixed value, terminate the process and define the peak valueof MU. Otherwise, increase the curvature by the amount of D and go to Step 4.

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Fig. 1

Flow chart of the procedure for the evaluation of the curve MStart
First step
ci-1 = 0
Calculation of the position of the neutral axis Ni-1=0
Increment of the curvature
ci = ci-1 + D c
Calculation of the strain e induced oneach structural element by the curvature ci
for the neutral axis position Ni-1
For each structural element; calculation of
the stress s relevant to the strain e

Curve s-e

Calculation of the new position of the neutral
axis Ni, imposing the equilibriumon the stress resultant FNo
Ni-1 = Ni

F = d1Yes

d1, d2 = specified tolerance on zero value

ci-1 = ci
No

Check on the positionof the neutral axis
Ni －Ni-1 < d2

Yes
Calculation of the bending moment
Mi relevant to the curvature ci summing thecontribution of each structural element stressNoc > cF
Yes
End

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Curve M-c

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Appendix 1)

2.1.2 Assumption
In applying the procedure described in 2.1.1, the following assumptions are generally to be made:・ the ultimate strength is calculated at hull transverse sections between two adjacent transverse webs.
・ the hull girder transverse section remains plane during each curvature increment.
・ the hull material has an elasto-plastic behaviour.
・ the hull girder transverse section is divided into a set of elements, which are considered to act independently.
These elements are:transversely framed plating panels and/or ordinary stiffeners with attached plating, whose structural
behaviour is described in 2.2.1
hard corners, constituted by plating crossing, whose structural behaviour is described in 2.2.2.
・ according to the iterative procedure, the bending moment Mi acting on the transverse section at each curvature
value i is obtained by summing the contribution given by the stress acting on each element. The stress ,corresponding to the element strain , is to be obtained for each curvature increment from the non-linear
load-end shortening curves - - of the element.
These curves are to be calculated, for the failure mechanisms of the element, from the formulae specified in 2.2.
The stress is selected as the lowest among the values obtained from each of the considered load-end shortening
curves - .
・ The procedure is to be repeated until the value of the imposed curvature reaches the value F, in m-1, in hogging
and sagging condition, obtained from the following formula:Mc F = 0.003 Y
EI Y
where:
MY : the lesser of the values MY1 and MY2, in kN-m:
MY1 = 103 ReH ZAB
MY2 = 103 ReH ZAD
If the value F is not sufficient to evaluate the peaks of the curve M- , the procedure is to be repeated until thevalue of the imposed curvature permits the calculation of the maximum bending moments of the curve.
2.1.3 Modeling of the hull girder cross section
Hull girder transverse sections are to be considered as being constituted by the members contributing to the hull
girder ultimate strength.
Sniped stiffeners are also to be modeled imaginarily, taking account that they doesn t contribute to the hull girderstrength.
The structural members are categorized into an ordinary stiffener element, a stiffened plate element or a hardcorner element.
The plate panel including web plate of girder or side stringer is idealized into either a stiffened plate element, an
attached plate of an ordinary stiffener element or a hard corner element.
The plate panel is categorized into the following two kinds:- longitudinally stiffened panel of which the longer side is in the longitudinal direction, and- transversely stiffened panel of which the longer side is in the perpendicular direction to the longitudinal direction.
・ Hard corner element
Hard corners elements are sturdier elements composing the hull girder transverse section, which collapse mainly
according to an elasto-plastic mode of failure (material yielding); they are generally constituted by two plates notlying in the same plane.
The extent of a hard corner element from the point of intersection of the plates is taken equal to 20tp ontransversely stiffened panel and to 0.5 s on a longitudinally stiffened panel. (See Fig. 6)
where:: Gross offered thickness of the plate, in mmtps: Spacing of the adjacent longitudinal stiffener, in m
Bilge, sheer strake-deck stringer elements, girder-deck connections and face plate-web connections on large
girders are typical hard corners.
・ Ordinary stiffener element
The ordinary stiffener constitutes an ordinary stiffener element together with the attached plate.
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The attached plate width is in principle:- equal to the mean spacing of the ordinary stiffener when the panels on both sides of the stiffener are
longitudinally stiffened, or- equal to the width of the longitudinally stiffened panel when the panel on one side of the stiffener islongitudinally stiffened and the other panel is of the transversely stiffened. (See Fig. 6)
・ Stiffened plate element
The plate between ordinary stiffener elements, between an ordinary stiffener element and a hard corner element or
between hard corner elements is to be treated as a stiffened plate element. (See Fig. 6)
Fig. 6

Extension of the breadth of the attached plating and hard corner elements 1=Min(20tp,s 2/2)s 2-s1-s３/2

s2-(s1+s3)/2

s4/2

s2
(Transversely
stiffened panel)

s2
s1
s3
(Longitudinally (Transversely (Longitudinally
stiffened panel) stiffened panel) stiffened panel)s4s3(Longitudinally
stiffened panel)

Ordinary stiffener element
Stiffened plate element
Hard corner element

The typical examples of modeling of hull girder section are illustrated in Figs. 7 and 8.
Notwithstanding the foregoing principle these figures are to be applied to the modeling in the vicinity of upper
deck, sheer strake and hatch side girder.
Fig. 7

Extension of the breadth of the attached plating and hard corner element
s2

s3

s2/2

s2/2

s3/2

s3/2

s6/2
s7

s1/2

s7/2

s1/2

: Ordinary stiffener element: Hard corner element

s7/2

s4/2

s4

s6

s4/2

s6/2

s1

s 8/2

2
s 8/
s8

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Appendix 1)

Fig. 8

Examples of the configuration of stiffened plate elements, ordinary stiffener elements and hard corner
elements on a hull section

s
s/2

20tp
20tp

Hard corner element
Ordinary stiffener element

Stiffened plate element

Note:(1) In case of the knuckle point as shown in Fig. 9, the plating area adjacent to knuckles in the plating with an angle greaterthan 30 degrees is defined as a hard corner. The extent of one side of the corner is taken equal to 20 tp on transversely framed
panels and to 0.5s on longitudinally framed panels from the knuckle point.
(2) Where the plate members are stiffened by non-continuous longitudinal stiffeners, the non-continuous stiffeners are
considered only as dividing a plate into various elementary plate panels.
(3) Where the opening is provided in the stiffened plate element, the openings are to be considered in accordance with Ch 5
Sec 1, 1.2.7, 1.2.8 and 1.2.9.
(4) Where attached plating is made of steels having different thicknesses and/or yield stresses, an average thickness and/or
average yield stress obtained by the following formula are to be used for the calculation.

t s +t s
t= 1 1 2 2 ,s

ReHp =

ReHp1t1 s1 + ReHp 2 t 2 s 2
ts

Where,
ReH1, ReH2, t1, t2, s1, s2 and s are shown in Fig. 10.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Appendix 1)

Fig. 9The case of plating with knuckle point

Knuckle pointaFig. 10

Element with different thickness and yield strength
s
s1

s2

t1
ReHp1

t2
ReHp2

2.2
Load-end shortening curves s-e
2.2.1 Stiffened plate element and ordinary stiffener element
Stiffened plate element and ordinary stiffener element composing the hull girder transverse sections may collapse
following one of the modes of failure specified in Table 1.
・ Where the plate members are stiffened by non-continuous longitudinal stiffeners, the stress of the element is tobe obtained in accordance with 2.2.3 to 2.2.7, taking into account the non-continuous longitudinal stiffener.
In calculating the total forces for checking the hull girder ultimate strength, the area of non-continuous
longitudinal stiffener is to be assumed as zero.
・ Where the opening is provided in the stiffened plate element, the considered area of the stiffened plate element
is to be obtained by deducting the opening area from the plating in calculating the total forces for checking thehull girder ultimate strength. The consideration of the opening is in accordance with the requirement in Ch 5 Sec
1, 1.2.7 to 1.2.9.
・ For stiffened plate element, the effective breadth of plate for the load shortening portion of the stress-strain
curve is to be taken as full plate breadth, i.e. to the intersection of other plate or longitudinal stiffener not fromthe end of the hard corner element nor from the attached plating of ordinary stiffener element, if any. In
calculating the total forces for checking the hull girder ultimate strength, the area of the stiffened plate element
is to be taken between the hard corner element and the ordinary stiffener element or between the hard corner
elements, as applicable.
2.2.2 Hard corner element
The relevant load-end shortening curve -e is to be obtained for lengthened and shortened hard corners according
to 2.2.3.

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Table 1

Modes of failure of stiffened plate element and ordinary stiffener element

Element

Mode of failure

Lengthened stiffened plate element orCurve s-e defined in

Elasto-plastic collapse

2.2.3

Beam column buckling

2.2.4

Torsional buckling

2.2.5

Web local buckling of flanged profiles

2.2.6

Web local buckling of flat bars

2.2.7

Plate buckling

2.2.8

ordinary stiffener element
Shortened ordinary stiffener element

Shortened stiffened plate element

2.2.3 Elasto-plastic collapse of structural elements
The equation describing the load-end shortening curve - e for the elasto-plastic collapse of structural elementscomposing the hull girder transverse section is to be obtained from the following formula, valid for both positive(shortening) and negative (lengthening) strains (see Fig. 2):
s = F ReHA
where:
ReHA : Equivalent minimum yield stress, in N/mm2, of the considered element, obtained by the following
formulaReHp A p + ReHs As
ReHA =Ap + AsFe: Edge function, equal to:= -1
for < -1=for -1
1=1for > 1
: Relative strain, equal to:
e
e= E
eY

eE :
eY :

Element strain
Strain at yield stress in the element, equal to:R
e Y = eHAE
Fig. 2

Load-end curve s-e for elasto plastic collapse
ReHA

-ReHA

2.2.4 Beam column buckling
The equation describing the load-end shortening curve CR1-e for the beam column buckling of ordinary stiffeners
composing the hull girder transverse section is to be obtained from the following formula (see Fig. 3):
AS + A pE
s CR1 = s C1
AS + A p
where:－169－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Appendix 1)

F : Edge function defined in 2.2.3
sC1 : Critical stress, in N/mm2, equal to:sRs C1 = E1
for s E1 £ eHB ee2æ ReHB e ö
ReHB
s C1 = ReHB çç1 for s E1 >e
4 s E1 ø
2è
ReHB : Equivalent minimum yield stress, in N/mm2, of the considered element, obtained by the following
formulaReHp A pE1l pE + ReHs As l sE
ReHB =
ApE1l pE + As l sE
ApE1 : Effective area, in cm2, equal to
ApE1 = 10bE1t p
lpE : Distance, in mm, measured from the neutral axis of the stiffener with attached plate of width bE1 to thebottom of the attached platelsE : Distance, in mm, measured from the neutral axis of the stiffener with attached plate of width bE1 to the
top of the stiffenere : Relative strain defined in 2.2.3
sE1 : Euler column buckling stress, in N/mm2, equal to:I
s E1 = p 2 E E 2 10 - 4
AE l
IE : Net moment of inertia of ordinary stiffeners, in cm4, with attached shell plating of width bE1
bE1 : Effective width, in m, of the attached shell plating, equal to:s
for b E > 1.0
b E1 =
bE
b E1 = sfor b E £ 1.0

b E = 103

s
tp

eReHp
E

ApE : Net sectional area, in cm2, of attached shell plating of width bE, equal to:
ApE = 10bE t p
bE : Effective width, in m, of the attached shell plating, equal to:æ 2.25 1.25 ö
b E = ççfor b E > 1.25
- 2 s
bE ø
è bE
bE = sfor b E £ 1.25
Fig. 3Load-end shortening curve

CR1-e for beam column buckling

2.2.5 Torsional buckling
The equation describing the load-end shortening curve CR2- for the flexural-torsional buckling of ordinary
stiffeners composing the hull girder transverse section is to be obtained according to the following formula (see Fig.
4).

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Appendix 1)

As s C 2 + A p s CP

s CR 2 =As + A p

where:
F : Edge function defined in 2.2.3
sC2 : Critical stress, in N/mm2, equal to:Rs
for s E 2 £ eHs e
sC2 = E22e
æ R eöR
s C 2 = ReHs çç1 - eHs
for s E 2 > eHs e
4s E2 ø2èsE2 : Euler torsional buckling stress, in N/mm2, defined in Ch 6, Sec 3, 4.3
e : Relative strain defined in 2.2.3
sCP : Buckling stress of the attached plating, in N/mm2, equal to:æ 2.25 1.25 ö- 2 ReHp for b E > 1.25
s CP = ççbE øè bEs CP = ReHp
for b E £ 1.25

bE : Coefficient defined in 2.2.4
Fig. 4Load-end shortening curve

CR2-e for flexural-torsional buckling

2.2.6 Web local buckling of ordinary stiffeners made of flanged profiles
The equation describing the load-end shortening curve CR3 -e for the web local buckling of flanged ordinary
stiffeners composing the hull girder transverse section is to be obtained from the following formula:
10 3 b E t p ReHp + (hwe t w + b f t f ) ReHs
s CR 3 =10 3 st p + hw t w + b f t f
where
F : Edge function defined in 2.2.3
bE : Effective width, in m, of the attached shell plating, defined in 2.2.4
hwe : Effective height, in mm, of the web, equal to:æ 2.25 1.25 ö- 2 hw
hwe = ççfor b w > 1.25
bw ø
è bw
hwe = hw
for b w £ 1.25

bw =

hw
tw

e ReHsE

e : Relative strain defined in 2.2.3
2.2.7 Web local buckling of ordinary stiffeners made of flat bars
The equation describing the load-end shortening curve CR4 -e for the web local buckling of flat bar ordinary
stiffeners composing the hull girder transverse section is to be obtained from the following formula (see Fig. 5):
A p s CP + As s C 4
s CR 4 =A p + As

where:－171－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 5 Appendix 1)

F : Edge function defined in 2.2.3
sCP : Buckling stress of the attached plating, in N/mm2, defined in 2.2.5
sC4 : Critical stress, in N/mm2, equal to:Rs
sC4 = E4
for s E 4 £ eHs e
2
e
æ
R eö
R
s C 4 = ReHs çç1 - eHs
for s E 4 > eHs e
4
s
2
E4 ø
è
sE4 : Local Euler buckling stress, in N/mm2, equal to:
2

e

æt ö
s E 4 = 160000çç w
è hw ø
: Relative strain defined in 2.2.3.

Fig. 5Load-end shortening curve

CR4-e for web local buckling

2.2.8 Plate buckling
The equation describing the load-end shortening curve CR5- for the buckling of transversely stiffened panels
composing the hull girder transverse section is to be obtained from the following formula:ì ReHpïï2
é s æ 2.25 1.25 ö
s CR 5 = min í1 ö ù
æ s öæç
ê
ú
ç
R
0
.
1
1
1
+
F
+
ç
ï eHp l ç bl øçè b E2 ø ú
b E2 ø
ê è E
è
ïî
ë
û
where:
F : Edge function defined in 2.2.3.

b E = 10 3
s
l

s
tp

eR eHpE: plate breadth, in m, taken as the spacing between the ordinary stiffeners.
: longer side of the plate, in m.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

Chapter 6

HULL SCANTLINGS

Section 1

PLATING

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Net moment of inertia, in m4, of the hull transverse section about its horizontal neutral axis, to be calculated
IY
according to Ch 5, Sec 1, 1.5, on gross offered thickness reduced by 0.5tC for all structural members: Net moment of inertia, in m4, of the hull transverse section about its vertical neutral axis, to be calculated
IZ
according to Ch 5, Sec 1, 1.5, on gross offered thickness reduced by 0.5tC for all structural membersN: Z co-ordinate with respect to the reference co-ordinate system defined in Ch 1, Sec 4, 4, in m, of the centreof gravity of the hull net transverse section, defined in Ch 5, Sec 1, 1.2, considering gross offered thickness
reduced by 0.5tC for all structural memberst: Net thickness, in mm, of a plate panel.
pS, pW : Still water and wave pressure, in kN/m2, in intact conditions, defined in 3.1.2: Pressure, in kN/m2, in flooded conditions, defined in 3.1.3
pF: Pressure, in kN/m2, in testing conditions, defined in 3.1.4
pT
sX: Normal stress, in N/mm2, defined in 3.1.5l: Length, in m, of the longer side of the elementary plate panel, measured along the chords: Length, in m, of the shorter side of the elementary plate panel, measured along the chord at mid-span of l
: Coefficient of aspect ratio of the plate panel, equal to:
ca
2

s
æsö
c a = 1.21 1 + 0.33ç
- 0.69, to be taken not greater than 1.0
l
èlø

cr

r

1.

: Coefficient of curvature of the panel, equal to:sc r = 1- 0.5, to be taken not less than 0.4
r: Radius of curvature, in m.

General1.1
Application
1.1.1
The requirements of this Section apply for the strength check of plating subjected to lateral pressure and, for
plating contributing to the longitudinal strength, to in-plane hull girder normal stress.
In addition, the buckling check of platings and stiffened panels is to be carried out according to Ch 6, Sec 3.
1.2
Net thicknesses
1.2.1
As specified in Ch 3, Sec 2, all thicknesses referred to in this Section are net, i.e. they do not include any corrosion
addition.
The gross thicknesses are obtained as specified in Ch 3, Sec 2, 3.
1.2.2
The net thickness, in mm, of each plating is given by the greatest of the net thicknesses calculated for each load
calculation point, as defined in 1.5.1, representative of the considered plating (see Table 1). The geometry to beconsidered is that of the elementary plate panel related to the load calculation point.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

1.3
Pressure combination
1.3.1 Elements of the outer shell
The still water and wave lateral pressures are to be calculated considering independently the following cases:
・ the still water and wave external sea pressures・ the static and dynamic internal pressure considering the compartment adjacent to the outer shell as being loaded.
If the compartment adjacent to the outer shell is intended to carry liquids, this static and dynamic pressures may
be reduced from the corresponding still water and wave external sea pressures.
1.3.2 Elements other than those of the outer shell
The static and dynamic lateral pressures to be considered as acting on an element which separates two adjacentcompartments are those obtained considering the two compartments individually loaded.
1.4
Elementary plate panel
1.4.1
The elementary plate panel (EPP) is the smallest unstiffened part of plating between stiffeners.
1.5
Load calculation point
1.5.1
Unless otherwise specified, lateral pressure and hull girder stresses are to be calculated:
・ for longitudinal framing, at the lower edge of the elementary plate panel (see Table 1) or, in the case ofhorizontal plating, at the point of minimum y-value among those of the elementary plate panel considered, as thecase may be・ for transverse framing, at the lower edge of the elementary plate panel or at the lower edge of the strake (seeTable 1) or, in the case of horizontal plating, at the point of minimum y-value among those of the elementary
plate panel considered, as the case may be.
Table 1

Load calculation points

Longitudinally stiffened plating

2.

Transversely stiffened plating

General requirements

2.1
Corrugated bulkhead
2.1.1
Unless otherwise specified, the net plating thickness of a corrugated bulkhead is to be not less than that obtained
for a plate panel with s equal to the greater of a and c, where a and c are defined in Fig 1.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

Fig. 1

Corrugated bulkhead
a
c

tf
R

tw

j ³ 55 odsC

2.2
Minimum net thicknesses
2.2.1
The net thickness of plating is to be not less than the values given in Table 2.
In addition, in the cargo area, the net thickness of side shell plating, from the normal ballast draught to 0.25TS(minimum 2.2 m) above TS, is to be not less than the value obtained, in mm, from the following formula:( BTS ) 0.25
t = 28( s + 0.7)
ReH
Table 2

Minimum net thickness of plating
Minimum net thickness, in mm

PlatingKeel

7.5 + 0.03LCSR-B

Bottom, inner bottom

5.5 + 0.03 LCSR-B

Weather strength deck and trunk deck, if any

4.5 + 0.02 LCSR-B

Side shell, bilge

0.85 LCSR-B 1/2

Inner side, hopper sloping plate and topside sloping plate

0.7 LCSR-B 1/2

Transverse and longitudinal watertight bulkheads

0.6 LCSR-B 1/2

Wash bulkheads

6.5

Accommodation deck

5.0

2.3
Bilge plating
2.3.1
The net thickness of the longitudinally framed bilge plating, in mm, is to be not less than the value obtained from
3.2.
2.3.2
The net thickness of the transversely framed bilge plating, in mm, is to be not less than the value obtained from thefollowing formula:0.4
t = 0.76[( p S + pW )s b ] R 0.6 k 0.5
where :
R : Bilge radius, in m
sb : Spacing of floors or transverse bilge brackets, in m.
2.3.3
The net thickness of the bilge plating is to be not less than the actual net thicknesses of the adjacent 2 m widthbottom or side plating, whichever is the greater.
2.4
Keel plating
2.4.1
The net thickness of the keel plating is to be not less than the actual net thicknesses of the adjacent 2 m widthbottom plating.

－175－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

2.5
Sheerstrake
2.5.1 Welded sheerstrake
The net thickness of a welded sheerstrake is to be not less than the actual net thicknesses of the adjacent 2 m widthside plating, taking into account higher strength steel corrections if needed.
2.5.2 Rounded sheerstrake
The net thickness of a rounded sheerstrake is to be not less than the actual net thickness of the adjacent deck
plating.
2.5.3 Net thickness of the sheerstrake in way of breaks of effective superstructures
The net thickness of the sheerstrake is to be increased in way of breaks of effective superstructures occurring
within 0.5LCSR-B amidships, over a length of about one sixth of the ship s breadth on each side of the superstructure
end.
This increase in net thickness is not to be less than 40% of the net thickness of sheerstrake other than those in wayof such breaks, but need not exceed 4.5 mm.
Where the breaks of superstructures occur outside 0.5LCSR-B amidships, the increase in net thickness may be
reduced to 30%, but need not exceed 2.5 mm.
2.5.4 Net thickness of the sheerstrake in way of breaks of non-effective superstructures
The net thickness of the sheerstrake is to be increased in way of breaks of non-effective superstructures occurring
within 0.6LCSR-B amidships, over a length of about one sixth of the ship s breadth on each side of the superstructure
end.
This increase in net thickness is to be equal to 15%, but need not exceed 4.5 mm.
2.6
Stringer plate
2.6.1 General
The net thickness of the stringer plate is to be not less than the actual net thickness of the adjacent deck plating.
2.6.2 Net thickness of the stringer plate in way of breaks of long superstructures
The net thickness of the stringer plate is to be increased in way of breaks of long superstructures occurring within
0.5LCSR-B amidships, over a length of about one sixth of the ship s breadth on each side of the superstructure end.
This increase in net thickness is not to be less than 40% of the net thickness of sheerstrake other than those in wayof such breaks, but need not exceed 4.5 mm.
Where the breaks of superstructures occur outside 0.5LCSR-B amidships, the increase in net thickness may be
reduced to 30%, but need not exceed 2.5 mm.
2.6.3 Net thickness of the stringer plate in way of breaks of short superstructures
The net thickness of the stringer plate is to be increased in way of breaks of short superstructures occurring within
0.6LCSR-B amidships, over a length of about one sixth of the ship breadth on each side of the superstructure end.
This increase in net thickness is to be equal to 15%, but need not exceed 4.5 mm.
2.7
Inner bottom loaded by steel coils on a wooden support
2.7.1 General
The net thickness of inner bottom, bilge hopper sloping plate and inner hull for ships intended to carry steel coils is
to comply with 2.7.2 to 2.7.4.
The provision is determined by assuming Fig 2 as the standard means of securing steel coils.
2.7.1 bis1 Accelerations
In order to calculate the accelerations, the following coordinates are to be used for the center of gravity.
xG - sc = 0.75 lH forward of aft bulkhead, where the hold of which the mid position is located forward from
0.45LCSR-B from A.E.
xG - sc = 0.75 lH afterward of fore bulkhead, where the hold of which the mid position is located afterward from
0.45LCSR-B from A.E.
B
yG - sc = e h43 üï d sc
ïìzG - sc = hDB + í1 + (n1 - 1)ý
2 ïþ 2ïî

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

where:
e : 1.0 when a port side structural member is considered , or -1.0 when a starboard side structural member
is considered.
Bh : breadth in m, at the mid of the hold, of the cargo hold at the level of connection of bilge hopper platewith side shell or inner hulld sc : diameter of steel coils, in m
hDB : height of inner bottom, in mlH : Cargo hold length, in m
Vertical acceleration a Z , in m/s2,are to be calculated by the formulae defined in Ch 4, Sec 2, 3.2 and tangential
acceleration a R due to roll, in m/s2 is to be calculated by the following formula:p æ 2p öçaR = q180 çè TR ø22

yG _ SC + R 2

where:
q , TR and R: as defined in Ch 4 Sec 2, 3.2.
2.7.2 Inner bottom plating
The net thickness of plating of longitudinally framed inner bottom is to be not less than the value obtained, in mm,from the following formula:{g (cos(C ZP F )cos(CZR q )) + a z }F
t = K1lP RY
where:
K1 : Coefficient taken equal to:
1.7 slK 2 - 0.73s 2 K 22 - (l - l')2l' (2 s + 2lK 2 )

2

K1 =

a Z : Vertical acceleration, in m/s2, defined in 2.7.1 bis1,

F : Single pitch amplitude, in deg, defined in Ch 4, Sec2, 2.2,
q : Single roll amplitude, in deg, defined in Ch 4, Sec2, 2.1,
CZP, CZR : Load combination factor defined in Ch 4, Sec4, 2.2
F : Force, in kg, taken equal to:
Wn1n2
for n2 £ 10 and n3 £ 5
F = KSn3
F = K S n1Wl
for n2 > 10 or n3 > 5lSlP : Coefficient defined in Table 6
KS : Coefficient taken equal to:when steel coils are lined up in one tier with a key coil
KS = 1.4
in other cases
KS = 1.0
W : Mass of one steel coil, in kg
n1 : Number of tiers of steel coilsn 2 : Number of load points per elementary plate panel (See Figs 3 and 4). When n3 £ 5 , n2 can beobtained from Table 3 according to the values of n3 and l / lS
n3 : Number of dunnages supporting one steel coill S : Length of a steel coil, in m
K2 : Coefficient taken equal to:
2

2

2

s
æsö
æ l ö æ l' ö
+ 2.33K2 = - + ç+ 1.37çç1 lèlø
èsø è lø－177－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)l¢ : Distance, in m, between outermost load points per elementary plate panel in ship length (See Figs 3
and 4). When n2 £ 10 and n3 £ 5 , l¢ can be obtained from Table 4 according to the values of l ,l S , n2 and n3. When n2 > 10 or n3 > 5 , l¢ is to be taken equal to l .
2.7.3 Bilge hopper sloping plate and inner hull plate
The net thickness of plating of longitudinally framed bilge hopper sloping plate and inner hull is to be not less thanthe value obtained, in mm, from the following formula:
ahopper F 't = K1l p Rywhere:
K1 : Coefficient defined in 2.7.2
qh : Angle, in deg, between inner bottom plate and bilge hopper sloping plate or inner hull plateæy G _ SCö
- q h + g cos(q h - C YG q ) cos(C XG F ) + CYS a sway sin q h
a hopper = -CYR a R sin ç tan -1
çRèøa R : tangential acceleration defined in 2.7.1 bis1.
asway : Transverse acceleration due to sway, in m/s2, defined in Ch 4, Sec 2, 2.4

CXG, CYS, CYR, CYG: Load combination factors defined in Ch 4, Sec 4, 2.2
yG_sc : Centre of gravity in transverse direction, in m, defined in 2.7.1 bis1
: Coefficient defined in Ch 4, Sec 2, 3.2.1
RF ¢ : Force, in kg, taken equal to:
Wn2Ck
F¢ =
for n2 £ 10 and n3 £ 5n3l
F ¢ = Ck W
for n2 > 10 or n3 > 5 ,lSlP: Coefficient defined in Table 6

W, n2, n3, F and q:
Ck : Coefficient taken equal to:
Ck = 3.2

2.7.4

Ck = 2.0(void)As defined in 2.7.2

when steel coils are lined up two or more tier, or when steel coils are lined up one tier and key
coil is located second or third from bilge hopper sloping plate or inner hull platefor other cases

Fig. 2

Inner bottom loaded by steel coils－178－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

Fig. 3

Loading condition of steel coils (Example of n2 = 4 , n3 = 3 )Steel coil

Dunnagen2 and l¢ are given by
Tables 3 and 4

Fig. 4

Inner bottom
Floor

BottomLoading condition of steel coils (Example of n2 = 3 , n3 = 3 )Steel coil

Dunnage

l¢

Floor

－179－

Inner bottom
Bottom2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

Table 3n2

Number n2 of load points per elementary plate paneln3 = 2n3 = 3

l
£ 0.5
lS

l
£ 0.33
lS

0<

2

0.5 <

l
£ 1.2
lS

0.33 <

l£ 0.67lS

0.25 <

3

1.2 <

l
£ 1.7
lS

0.67 <

l
£ 1.2
lS

0.5 <

4

1.7 <

l
£ 2.4
lS

1.2 <

l
£ 1.53lS

0.75 <

5

2.4 <

l
£ 2.9
lS

1.53 <

l£ 1.87
lS

1.2 <

6

2.9 <

l
£ 3.6
lS

1.87 <

l£ 2.4
lS

1.45 <

7

3.6 <

l
£ 4.1
lS

2.4 <

l
£ 2.73
lS

1.7 <

8

4.1 <

l
£ 4.8
lS

2.73 <

l£ 3.07lS

1.95 <

9

4.8 <

l
£ 5.3
lS

3.07 <

l
£ 3.6
lS

2.4 <

10

5.3 <

l
£ 6.0
lS

3.6 <

l
£ 3.93lS

2.65 <

n20<l£ 0.25lS

1Table 40<n3 = 4n3 = 5
0<

l
£ 0.5
lS

0.2 <

l
£ 0.4
lS

l
£ 0.75
lS

0.4 <

l
£ 0.6
lS

l
£ 1.2
lS

0.6 <

l
£ 0.8
lS

l
£ 1.45
lS

0.8 <

l
£ 1.2
lS

l
£ 1.7
lS

1.2 <

l
£ 1.4
lS

l
£ 1.95
lS

1.4 <

l
£ 1.6
lS

l
£ 2.4
lS

1.6 <

l
£ 1.8
lS

l
£ 2.65
lS

1.8 <

l
£ 2.0
lS

l
£ 2.9
lS

2.0 <

l
£ 2.4
lS

Distance between load points in ship length direction
per elementary plate panel of inner bottom
n3
2

1

3

4

5

Actual breadth of dunnage

2

0.5lS

0.33lS

0.25lS

0.2lS

3

1.2lS

0.67lS

0.50lS

0.4lS

4

1.7lS

1.20lS

0.75lS

0.6lS

5

2.4lS

1.53lS

1.20lS

0.8lS

6

2.9lS

1.87lS

1.45lS

1.2lS

7

3.6lS

2.40lS

1.70lS

1.4lS

8

4.1lS

2.73lS

1.95lS

1.6lS

9

4.8lS

3.07lS

2.40lS

1.8lS

10

5.3lS

3.60lS

2.65lS

2.0lS

－180－

l
£ 0.2
lS

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

3.

Strength check of plating subjected to lateral pressure

3.1
Load model
3.1.1 General
The static and dynamic lateral pressures induced by the sea and the various types of cargoes and ballast in intact
conditions are to be considered, depending on the location of the plating under consideration and the type of thecompartments adjacent to it.
The plating which constitutes the boundary of compartments not intended to carry liquid (excluding bottom andside shell plating) is to be subjected to lateral pressure in flooded conditions.
The wave lateral pressures and hull girder loads are to be calculated, for the probability level of 10-8, in themutually exclusive load cases H1, H2, F1, F2, R1, R2, P1 and P2, as defined in Ch 4, Sec 4.
3.1.2 Lateral pressure in intact conditions
The lateral pressure in intact conditions is constituted by still water pressure and wave pressure.
Still water pressure pS includes:
・ the hydrostatic pressure, defined in Ch 4, Sec 5, 1・ the still water internal pressure, defined in Ch 4, Sec 6 for the various types of cargoes and for ballast.
Wave pressure pW includes for each load case H1, H2, F1, F2, R1, R2, P1 and P2:・ the hydrodynamic pressure, defined in Ch 4, Sec 5, 1・ the inertial pressure, defined in Ch 4, Sec 6 for the various types of cargoes and for ballast.
3.1.3 Lateral pressure in flooded conditions
The lateral pressure in flooded conditions pF is defined in Ch 4, Sec 6, 3.2.1.
3.1.4 Lateral pressure in testing conditions
The lateral pressure pT in testing conditions is taken equal to:
・ pT = pST - pS
for bottom shell plating and side shell platingotherwise,・ pT = pST
where:
pST : Testing pressure defined in Ch 4, Sec 6, 4
pS : Pressure taken equal to:・ if the testing is carried out afloat: hydrostatic pressure defined in Ch 4, Sec 5, 1 for the draught T1,
defined by the Designer, at which the testing is carried out. If T1 is not defined, the testing is
considered as being not carried out afloat
・ if the testing is not carried out afloat: pS = 0
3.1.5 Normal stresses
The normal stress to be considered for the strength check of plating contributing to the hull girder longitudinalstrength is the maximum value of sX between sagging and hogging conditions, when applicable, obtained, in N/mm2,
from the following formula:
é
ù
M
M
M
s X = êC SW SW ( z - N ) + CWV WV ( z - N ) - CWH WH y ú10 -3
IY
IY
IZ
ëê
ûú
where:MSW
MWV: Permissible still water bending moments, in kN-m, in hogging or sagging as the case may be: Vertical wave bending moment, in kN-m, in hogging or sagging as the case may be, as definedin Ch 4, Sec 3: Horizontal wave bending moment, in kN-m, as defined in Ch 4, Sec 3
MWH: Combination factor for each load case H1, H2, F1, F2, R1, R2, P1 and P2 and defined in Table
CSW
5
CWV, CWH : Combination factors defined in Ch 4, Sec 4, 2.2 for each load case H1, H2, F1, F2, R1, R2, P1
and P2 and given in Table 5.

－181－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

Table 5LC

Hogging

CSW

CWH

Not Applicable
1

1

F1
F2

Sagging

CWV

H1
H2

Combination factors CSW, CWV and CWH
CWV

CWH

-1

-1

0

0

Not Applicable

Not Applicable
1

CSW

-1

-1

0

1

0

Not Applicable
-1

0

1.2 -

TLC
- 1.2
TS

R1

1

0

T
1.2 - LC
TS

R2

1

0

TLC
- 1.2
TS

-1

0

P1

1

0.4 -

TLC
TS

0

-1

0.4 -

TLC
TS

0

P2

1

TLC
- 0.4
TS

0

-1

TLC
- 0.4
TS

0

TLC
TS

3.2
Plating thickness
3.2.1 Intact conditions
The net thickness of laterally loaded plate panels is to be not less than the value obtained, in mm, from thefollowing formula:t = 15.8c a c r s

p S + pWl P RY

where:
lP : Coefficient defined in Table 6
Coefficient lP

Table 6

Coefficient lP

Plating
Longitudinally framed platings
0.95 - 0.45 X
RY, without being taken greater than 0.9

Transversely framed plating

0.95 - 0.90

sX
RY

, without being taken greater than 0.9

Contributing to the hull
girder longitudinal strength

Not contributing to the hull girder longitudinal strength

0.9

3.2.2

Net thickness under flooded conditions excluding corrugations of transverse vertically corrugated bulkhead
separating cargo holds
The plating which constitutes the boundary of compartments not intended to carry liquids (excluding bottom
plating and side shell plating), and excluding corrugations of transverse vertically corrugated bulkhead separatingcargo holds is to be checked in flooded conditions. To this end, its net thickness is to be not less than the value
obtained, in mm, from the following formula:t = 15.8c a c r s

pF
al P RY

where:
lP : Coefficient defined in Table 6, determined by considering sX in flooded conditiona : Coefficient taken equal to:a = 0.95
for the plating of collision bulkhead
a = 1.15
for the plating of other watertight boundaries of compartments.

－182－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

3.2.3

Net thickness of the corrugations of transverse vertically corrugated watertight bulkheads separating cargoholds for flooded conditions
The net plate thickness t, in mm, of transverse vertically corrugated watertight bulkheads separating cargo holds is
to be not less than that obtained from the following formula:
1.05 pt = 14.9 s
ReH

p : Pressure pF or resultant pressure p, in kN/m2, as defined in Ch 4, Sec 6, 3.3.6 and 3.3.7, respectivelys : Plate width, in m, to be taken equal to the width of the corrugation flange or web, whichever is greater.
For built-up corrugation bulkheads, when the thicknesses of the flange and web are different:・ the net thickness of the narrower plating is to be not less than that obtained, in mm, from the following formula:t N = 14.9s

1.05 pR eH

s : Plate width, in m, of the narrower plating
・ the net thickness of the wider plating is not to be less than the greater of those obtained, in mm, from thefollowing formulae:
1.05 ptW = 14.9s
R eH
tW =

462s 2 p 2- t NP
ReH

where:
tNP : Actual net thickness of the narrower plating, in mm, to be not taken greater than:
1.05 pt NP = 14.9s
R eH
s : Plate width, in m, to be taken equal to the width of the corrugation flange or web, whichever is greater.
The net thickness of the lower part of corrugations is to be maintained for a distance from the inner bottom (if nolower stool is fitted) or the top of the lower stool not less than 0.15lC, where lC is the span of the corrugations, in m,
to be obtained according to Ch 3, Sec 6, 10.4.4. The net thickness is also to comply with the requirements in 3.2.1,
Sec 2, 3.6.1 and 3.6.2, and Sec 3, 6.
The net thickness of the middle part of corrugations is to be maintained for a distance from the deck (if no upperstool is fitted) or the bottom of the upper stool not greater than 0.3lC. The net thickness is also to comply with therequirements in 3.2.1 and Sec 2, 3.6.1 and 3.6.2.
Fig. 5

Parts of Corrugation－183－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 1)

3.2.3 bis1 Net thickness of lower stool and upper stool
The net thickness and material of the stool top plate of lower stool are to be not less than those for the corrugatedbulkhead plating above required by 3.2.3.
The net thickness and material of the upper portion of vertical or sloping stool side plating of lower stool within
the depth equal to the corrugation flange width from the stool top are to be not less than the flange plate at the lower
end of the corrugation required by 3.2.3, as applicable, whichever is the greater.
The net thickness and material of the stool bottom plate of upper stool are to be the same as those of the bulkhead
plating below required by 3.2.3, as applicable, whichever is the greater.
The net thickness of the lower portion of stool side plating is to be not less than 80% of the upper part of thebulkhead plating required by 3.2.3, as applicable, whichever is the greater, where the same material is used.
The net thicknesses of lower stool and upper stool are to be not less than those required by 3.2.1, 3.2.2 and 3.2.4.
3.2.3 bis2 Net thickness of supporting floors of corrugated bulkhead
The net thickness and material of the supporting floors and pipe tunnel beams of corrugated bulkhead, when nostool is fitted, are to be not less than those of the corrugation flanges required by 3.2.3.
When a lower stool is fitted, the net thickness of supporting floors are to be not less than that of the stool side
plating required by the first sentence of 3.2.2.
3.2.4 Testing conditions
The plating of compartments or structures as defined in Ch 4, Sec 6, 4 is to be checked in testing conditions. To
this end, its net thickness is to be not less than the value obtained, in mm, from the following formula:t = 15.8c a c r s

pT
1.05RY－184－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

Section 2

ORDINARY STIFFENERS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Rule length LCSR-B, but to be taken not greater than 300 m: Net moment of inertia, in m4, of the hull transverse section about its horizontal neutral axis, to be calculated
according to Ch 5, Sec 1, 1.5, on gross offered thickness reduced by 0.5tC for all structural members: Net moment of inertia, in m4, of the hull transverse section about its vertical neutral axis, to be calculated
IZ
according to Ch 5, Sec 1, 1.5, on gross offered thickness reduced by 0.5tC for all structural membersN: Z co-ordinate with respect to the reference co-ordinate system defined in Ch 1, Sec 4, 4, in m, of the centreof gravity of the hull net transverse section defined in Ch 5, Sec 1, 1.2, considering gross offered thickness
reduced by 0.5tC for all structural members
pS, pW : Still water and wave pressure, in kN/m2, in intact conditions, defined in 3.1.2: Pressure, in kN/m2, in flooded conditions, defined in 3.1.3
pF: Pressure, in kN/m2, in testing conditions, defined in 3.1.4
pT
sX: Normal stress, in N/mm2, defined in 3.1.5s: Spacing, in m, of ordinary stiffeners, measured at mid-span along the chordl: Span, in m, of ordinary stiffeners, measured along the chord between the supporting members, see Ch 3,
Sec 6, 4.2: Web height, in mm
hw: Net web thickness, in mmtw: Face plate width, in mm
bf: Net face plate thickness, in mm
tf: Width, in m, of the plating attached to the stiffener, for the yielding check, defined in Ch 3, Sec 6, 4.3
bpw: Net section modulus, in cm3, of the stiffener, with an attached plating of width bp, to be calculated as
specified in Ch 3, Sec 6, 4.4
Ash : Net shear sectional area, in cm2, of the stiffener, to be calculated as specified in Ch 3, Sec 6, 4.4m: Coefficient taken equal to:m = 10 for vertical stiffeners
m = 12 for other stiffenersta: Allowable shear stress, in N/mm2, taken equal to:Rta = Y
3
L2
IY

1.

General1.1
Application
1.1.1
The requirements of this Section apply for the yielding check of ordinary stiffeners subjected to lateral pressure
and, for ordinary stiffeners contributing to the hull girder longitudinal strength, to hull girder normal stresses.
The yielding check is also to be carried out for ordinary stiffeners subjected to specific loads, such as concentrated
loads.
In addition, the buckling check of ordinary stiffeners is to be carried out according to Ch 6, Sec 3.
1.2
Net scantlings
1.2.1
As specified in Ch 3, Sec 2, all scantlings referred to in this Section are net, i.e. they do not include any corrosion
addition.

－185－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

The gross scantlings are obtained as specified in Ch 3, Sec 2, 3.
1.3
Pressure combination
1.3.1 Elements of the outer shell
The still water and wave lateral pressures are to be calculated considering independently the following cases:
・ the still water and wave external sea pressures・ the still water and wave internal pressure considering the compartment adjacent to the outer shell as being
loaded. If the compartment adjacent to the outer shell is intended to carry liquids, this still water and wave
internal pressures are to be reduced from the corresponding still water and wave external sea pressures.
1.3.2 Elements other than those of the outer shell
The still water and wave lateral pressures to be considered as acting on an element which separates two adjacentcompartments are those obtained considering the two compartments individually loaded.
1.4
Load calculation point
1.4.1 Horizontal stiffeners
Unless otherwise specified, lateral pressure and hull girder stress, if any, are to be calculated at mid-span of theordinary stiffener considered.
1.4.2 Vertical stiffeners
The lateral pressure p is to be calculated as the maximum between the value obtained at mid-span and the value
obtained from the following formula:p + pL, when the upper end of the vertical stiffener is below the lowest zero pressure level
・ p= U2l p
・ p = 1 L , when the upper end of the vertical stiffener is at or above the lowest zero pressure level (see Fig. 1)
l 2
where:
l1: Distance, in m, between the lower end of vertical stiffener and the lowest zero pressure levelpU, pL : Lateral pressures at the upper and lower end of the vertical stiffener span l, respectively.
Fig. 12.
2.1

Definition of pressure for vertical stiffeners

General requirements(void)
Fig. 2(void)

2.2
Net thicknesses of webs of ordinary stiffeners
2.2.1 Minimum net thicknesses of webs of ordinary stiffeners other than side frames of single side bulk carriers
The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:・ t = 3.0 + 0.015L2
・ 40% of the net required thickness of the attached plating, to be determined according to Ch.6, Sec.1.

－186－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

2.2.2 Minimum net thicknesses of side frames of single side bulk carriers
The net thickness of side frame webs within the cargo area, in mm, is to be not less than the value obtained fromthe following formula:tMIN = 0.75 a (7 + 0.03LCSR-B)
where:
a : Coefficient taken equal to:a = 1.15
for the frame webs in way of the foremost holda = 1.00
for the frame webs in way of other holds.
2.2.3 Maximum net thickness of web of ordinary stiffener
The net thickness of the web of ordinary stiffeners, in mm, is to be less than 2 times the net offered thickness of theattached plating.
2.3
Net dimensions of ordinary stiffeners
2.3.1 Flat bar
The net dimensions of a flat bar ordinary stiffener (see Fig. 3) are to comply with the following requirement:hw£ 20 ktw
Net dimensions of a flat bar

twhw

Fig. 32.3.2 T-section
The net dimensions of a T-section ordinary stiffener (see Fig. 4) are to comply with the following requirements:hw£ 65 ktwtf£ 33 kbf t f ³

hwt w
6

Fig. 4

Net dimensions of a T-section

tw

hw

bf

tf

bf

－187－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

2.3.3 Angle
The net dimensions of an angle ordinary stiffener (see Fig. 5) are to comply with the following requirements:hw£ 55 ktwbf
tf£ 16.5 k

bf t f ³

hwt w
6

Net dimensions of an angle

hw

Fig. 5

tw
tf
bf

2.4
Struts connecting ordinary stiffeners
2.4.1
The net sectional area ASR, in cm2, and the minimum net moment of inertia ISR about the axes perpendicular to thestrut, in cm4, of struts connecting ordinary stiffeners are to be not less than the values obtained from the following
formulae:p sl
ASR = SR20
0.75sl( p SR1 + p SR 2 )A ASR l 2SR
SR =47.2 A ASR - sl( p SR1 + p SR 2 )where:: Pressure to be taken equal to the greater of the values obtained, in kN/m2, from the following formulae:pSR
pSR = 0.5( p SR1 + pSR 2 )pSR = pSR3

pSR1 : External pressure in way of the strut, in kN/m2, acting on one side, outside the compartment in which
the strut is located
pSR2 : External pressure in way of the strut, in kN/m2, acting on the opposite side, outside the compartment
in which the strut is located
pSR3 : Internal pressure at mid-span of the strut, in kN/m2, in the compartment in which the strut is locatedl: Span, in m, of ordinary stiffeners connected by the strut (see Ch 3, Sec 6, 4.2.3)
lSR : Length, in m, of the strut
AASR : Actual net sectional area, in cm2, of the strut.
2.5
Ordinary stiffeners of inner bottom loaded by steel coils on a wooden support
2.5.1 General
The requirements of this sub-article apply to the ordinary stiffeners located on inner bottom plate, bilge hopper
sloping plate and inner hull plate when loaded by steel coils on a wooden support (dunnage), as indicated in Fig 2 of
Ch 6, Sec 1.
2.5.2 Ordinary stiffeners located on inner bottom plating
The net section modulus w , in cm3, and the net shear sectional area Ash , in cm2, of single span ordinary stiffeners
located on inner bottom plating are to be not less than the values obtained from the following formulae:－188－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

w = K3{g (cos(CZP F) cos(CZRq ) ) + aZ }F

8lS RY
5{g (cos(C ZP F) cos(C ZR q )) + a Z }F -3Ash =10t a sin fwhere:
K3 : Coefficient defined in Table 1. When n2 is greater than 10, K 3 is to be taken equal to 2l/3
aZ : Vertical acceleration, in m/s2, defined in Ch 6, Sec1, 2.7.1 bis1
F : Single pitch amplitude, in deg, defined in Ch 4, Sec 2, 2.2
q : Single roll amplitude, in deg, defined in Ch 4, Sec 2, 2.1
CZP, CZR : Load combination factor defined in Ch 4, Sec 4, 2.2
F : Force, in kg, defined in Ch 6, Sec 1, 2.7.2
lS : Coefficient defined in Table 3
f : Angle, in deg, defined in 3.2.3.
2.5.3 Ordinary stiffeners located on bilge hopper sloping plate or inner hull plate
The net section modulus w , in cm3, and the net shear sectional area Ash , in cm2, of single span ordinary stiffeners
located on bilge hopper sloping plate and inner hull plate are to be not less than the values obtained from thefollowing formulae:

w = K3Ash =ahopper F '8lS RY

5ahopper F 't a sin f

10 -3

where:
K3 : Coefficient defined in Table 1. When n2 > 10 , K 3 is taken equal to 2l/3
qh : Angle, in deg, between inner bottom plate and bilge hopper sloping plate or inner hull plateahopper : Acceleration, in m/s2, defined in Ch 6, Sec 1, 2.7.3
F'
lS
f
l'

:
:
:
:

Force, in kg, defined in Ch 6, Sec 1, 2.7.3
Coefficient defined in Table 3
Angle, in deg, defined in 3.2.3
Distance, in m, between between outermost load points per elementary plate panel in ship length
Table 1

n2

1

2

3
'2

K3

l

2.5.4

(void)

l-

l
l

4
'2

l-

2l
3l

5
'2

l-

Coefficient K3

5l
9l

6
'2

l-

l
2l

7
'2

l-

7l
15l

8
'2

l-

4l
9l

9
'2

l-

3l
7l

10
'2

l-

5l
12l

l-

11l ' 227l

2.6
Deck ordinary stiffeners in way of launching appliances used for survival craft or rescue boat
2.6.1
The scantlings of deck ordinary stiffeners are to be determined by direct calculations.
2.6.2
The loads exerted by launching appliance are to correspond to the Safe Working Load of the launching appliance.
2.6.3
The combined stress, in N/mm2, is not to exceed the smaller of:100
54
ReH andRm
235
235
where Rm is the ultimate tensile strength of the stiffener material, in N/mm2.

－189－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

3.

Yielding check

3.1
Load model
3.1.1 General
The still water and wave lateral loads induced by the sea and the various types of cargoes and ballast in intact
conditions are to be considered, depending on the location of the ordinary stiffener under consideration and the typeof the compartments adjacent to it.
Ordinary stiffeners located on plating which constitutes the boundary of compartments not intended to carryliquids (excluding those on bottom and side shell plating) are to be subjected to the lateral pressure in flooded
conditions.
The wave lateral loads and hull girder loads are to be calculated, for the probability level of 10-8, in the mutually
exclusive load cases H1, H2, F1, F2, R1, R2, P1 and P2, as defined in Ch 4, Sec 4.
3.1.2 Lateral pressure in intact conditions
The lateral pressure in intact conditions is constituted by still water pressure and wave pressure.
Still water pressure pS includes:
・ the hydrostatic pressure, defined in Ch 4, Sec 5, 1・ the still water internal pressure, defined in Ch 4, Sec 6 for the various types of cargoes and for ballast.
Wave pressure pW includes for each load case H1, H2, F1, F2, R1, R2, P1 and P2:・ the hydrodynamic pressure, defined in Ch 4, Sec 5, 1・ the inertial pressure, defined in Ch 4, Sec 6 for the various types of cargoes and for ballast.
3.1.3 Lateral pressure in flooded conditions
The lateral pressure in flooded conditions pF is defined in Ch 4, Sec 6, 3.2.1.
3.1.4 Lateral pressure in testing conditions
The lateral pressure pT in testing conditions is taken equal to:
・ pT = pST - pS
for bottom shell plating and side shell platingotherwise,・ pT = pST
where:
pST : Testing pressure defined in Ch 4, Sec 6, 4
pS : Pressure taken equal to:・ if the testing is carried out afloat: hydrostatic pressure defined in Ch 4, Sec 5, 1 for the draught T1,
defined by the Designer, at which the testing is carried out. If T1 is not defined, the testing is
considered as being not carried out afloat
・ if the testing is not carried out afloat: pS = 0
3.1.5 Normal stresses
The normal stress to be considered for the strength check of ordinary stiffeners contributing to the hull girderlongitudinal strength is the maximum value of sX between sagging and hogging conditions, when applicable,
obtained , in N/mm2, from the following formula:
é
ù
M
M
M
s X = êC SW SW ( z - N ) + CWV WV ( z - N ) - CWH WH y ú 10 -3
IY
IY
IZ
ëê
ûú
where:MSW
MWV: Permissible still water bending moments, in kN-m, in hogging or sagging as the case may be: Vertical wave bending moment, in kN-m, in hogging or sagging as the case may be, as definedin Ch 4, Sec 3: Horizontal wave bending moment, in kN-m, as defined in Ch 4, Sec 3
MWH: Combination factor for each load case H1, H2, F1, F2, R1, R2, P1 and P2 and defined in Table
CSW
2
CWV, CWH : Combination factors defined in Ch 4, Sec 4, 2.2 for each load case H1, H2, F1, F2, R1, R2, P1
and P2 and given in Table 2.

－190－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

Table 2
LC

Hogging
CSW

H1
H2

Combination factors CSW, CWV and CWH
Sagging

CWV

CWH

Not Applicable
1

F1

1

CSW

CWV

CWH

-1

-1

0

0

Not Applicable

Not Applicable

-1

-1

0

F2

1

1

0

Not Applicable

R1

1

0

1.2 -

TLC
TS

-1

0

1.2 -

R2

1

0

TLC
- 1.2
TS

-1

0

TLC
- 1.2
TS

P1

1

0.4 -

TLC
TS

0

-1

0.4 -

TLC
TS

0

P2

1

TLC
- 0.4
TS

0

-1

TLC
- 0.4
TS

0

TLC
TS

3.2

Strength criteria for single span ordinary stiffeners other than side frames of single side bulk
carriers
3.2.1 Boundary conditions
The requirements of this sub-article apply to ordinary stiffeners considered as clamped at both ends.
For other boundary conditions, the yielding check is to be considered on a case by case basis.
3.2.2 Groups of equal ordinary stiffeners
Where a group of equal ordinary stiffeners is fitted, it is acceptable that the minimum net section modulus in 3.2.3
to 3.2.7 is calculated as the average of the values required for all the stiffeners of the same group, but this average is
to be taken not less than 90% of the maximum required value.
The same applies for the minimum net shear sectional area.
3.2.3 Net section modulus and net shear sectional area of single span ordinary stiffeners under intact conditions
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of single span ordinary stiffeners
subjected to lateral pressure are to be not less than the values obtained from the following formulae:( p + pW )sl 2 3
10
w= S
m l S RY
5( p S + pW )sl
Ash =t a sin fwhere:
lS : Coefficient defined in Table 3.
f : Angle, in deg, between the stiffener web and the shell plate, measured at the middle of the stiffener
span; the correction is to be applied when f is less than 75 deg.
Table 3

Coefficient lS

Ordinary stiffener

Coefficient lS

Longitudinal stiffener ccontributing to the hull girderæs ö
1.2ç1.0 - 0.85 X, without being taken greater than 0.9
ç
RY ø
è

longitudinal strength
Other stiffeners

0.9

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

3.2.4 Net section modulus of corrugated bulkhead of ballast hold for ships having a length (LCSR-B) less than 150m
The net section modulus w, in cm3, of corrugated bulkhead of ballast hold for ships having a length (LCSR-B) lessthan 150m subjected to lateral pressure are to be not less than the values obtained from the following formula:( p + pW )s C l 2 3
10
w=K S
m l S RY
where:
K : Coefficient given in Table 4 and 5, according to the type of end connection. When d H < 2.5d 0 , both
section modulus per half pitch of corrugated bulkhead and section modulus of lower stool at inner
bottom are to be calculated.
sC : Half pitch length, in m, of the corrugation, defined in Ch 3, Sec 6, Fig. 28
l : Length, in m, between the supports, as indicated in Fig. 6
lS : Coefficient defined in Table 3.
The effective width of the corrugation flange in compression is to be considered according to Ch3, Sec 6, 10.4.10
when the net section modulus of corrugated bulkhead is calculated.
Table 4

Values of K, in case d H ³ 2.5d 0Upper end support

Supported by girders

Welded directly to deck

Welded to stool efficiently
supported by ship structure

1.25

1.00

Table 50.83

Values of K, in case d H < 2.5d 0Upper end support

Section modulus of

Supported by girders

Connected to Deck

Connected to stool

Corrugated bulkhead

0.83

0.71

0.65

Stool at bottom

0.83

1.25

1.13

Fig. 6

Measurement of ld H ³ 2.5d0

d H < 2.5d0

B

B
e

A

d0

e

A

l

d0

dH

dH
e = A(1 - d 0 / 2 B )

－192－

l

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

3.2.5

Net section modulus and net shear sectional area of single span ordinary stiffeners under flooded conditions
excluding corrugations of transverse vertically corrugated bulkhead separating cargo holds
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of single span ordinary stiffeners
excluding corrugations of transverse vertically corrugated bulkhead separating cargo holds subjected to flooding are
to be not less than the values obtained from the following formulae:p F sl 2
10 3
w=
16al S RY
5 p F slAsh =at a sin fwhere:
lS, f : Coefficient and angle defined in 3.2.3, lS being determined by considering sX in flooded condition.
a: Coefficient taken equal to:a = 0.95
for the ordinary stiffeners of collision bulkhead,a = 1.15
for the ordinary stiffeners of other watertight boundaries of compartments.
without taken alS greater than 1.0
3.2.6 (void)3.2.7 Net section modulus and net shear sectional area of single span ordinary stiffeners under testing conditions
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of single span ordinary stiffeners
subjected to testing are to be not less than the values obtained from the following formulae:
p sl 2
10 3
w= T
1.05mRY
5 p T sl
Ash =1.05t a sin fwhere:
f : Angle, in deg, defined in 3.2.3.
3.3
Strength criteria for side frames of single side bulk carriers
3.3.1 Net section modulus and net shear sectional area of side frames
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of side frames subjected to lateralpressure are to be not less, in the mid-span area, than the values obtained from the following formulae:( p + pW )sl 2 3
10
w = 1.125a m S
m l S RY
Ash = 1.1a S

5( p S + pW )sl æ l - 2l B öçt a sin f çè l ø

where:am: Coefficient taken equal to:am = 0.42 for BC-A ships
am = 0.36 for other shipslS: Coefficient taken equal to 0.9l: Side frame span, in m, defined in Ch 3, Sec 6, Fig. 19, to be taken not less than 0.25D
aS: Coefficient taken equal to:aS = 1.1 for side frames of holds specified to be empty in BC-A ships
aS = 1.0 for other side frames: Lower bracket length, in m, defined in Fig 7
lB
ps , pw : Still water and wave pressures, in kN/m2, in intact conditions calculated as defined in 1.3 and1.4.2.
In addition, for side frames of holds intended to carry ballast water in heavy ballast condition, the net section
modulus w, in cm3, and the net shear sectional area Ash, in cm2, all along the span are to be in accordance with 3.2.3, lbeing the span of the side frame as defined in Ch.3, Sec.6, 4.2, with consideration to brackets at ends.

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Fig. 7

Side frame lower bracket lengthll3.3.2 Supplementary strength requirements
In addition to 3.3.1, the net moment of inertia, in cm4, of the 3 side frames located immediately abaft the collisionbulkhead is to be not less than the value obtained from the following formula:( p + pW )l 4
= 0.18 Snwhere:
l : Side frame span, in m
n : Number of frames from the bulkhead to the frame in question, taken equal to 1, 2 or 3
As an alternative, supporting structures, such as horizontal stringers, are to be fitted between the collision bulkhead
and a side frame which is in line with transverse webs fitted in both the topside tank and hopper tank, maintaining thecontinuity of forepeak stringers within the foremost hold.
3.3.3 Lower bracket of side frame
At the level of lower bracket as shown in Ch 3, Sec 6, Fig. 19, the net section modulus of the frame and bracket, or
integral bracket, with associated shell plating, is to be not less than twice the net section modulus w required for theframe mid-span area obtained from 3.3.1.
In addition, for holds intended to carry ballast water in heavy ballast condition, the net section modulus w, in cm3,at the level of lower bracket is to be not less than twice the greater of the net sections moduli obtained from 3.2.3 and3.3.1.
The net thickness tLB of the frame lower bracket, in mm, is to be not less than the net thickness of the side frame
web plus 1.5 mm.
Moreover, the net thickness tLB of the frame lower bracket is to comply with the following formula:h LB・ for symmetrically flanged frames:£ 87 kt LB
h LB
・ for asymmetrically flanged frames :£ 73 kt LB
The web depth hLB of lower bracket may be measured from the intersection between the sloped bulkhead of thehopper tank and the side shell plate, perpendicularly to the face plate of the lower bracket (see Ch 3, Sec 6, Fig. 22).
For the 3 side frames located immediately abaft the collision bulkhead, whose scantlings are increased according to
3.3.2, when tLB is greater than 1.73tw, the thickness tLB may be taken as the value t LB obtained from the following
formula:

(

'
2
t LB
= t LBtw)1

3

where tw is the net thickness of the side frame web, in mm, corresponding to Ash determined in accordance to
3.3.1.
The flange outstand is not to exceed 12k0.5 times the net flange thickness.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

3.3.4 Upper bracket of side frame
At the level of upper bracket as shown in Ch 3, Sec 6, Fig 19, the net section modulus of the frame and bracket, or
integral bracket, with associated shell plating, is to be not less than twice the net section modulus w required for theframe mid-span area obtained from 3.3.1.
In addition, for holds intended to carry ballast water in heavy ballast condition, the net section modulus w, in cm3,at the level of upper bracket is not to be less than twice the greater of the net sections moduli obtained from 3.2.3 and3.3.1.
The net thickness tUB of the frame upper bracket, in mm, is to be not less than the net thickness of the side frame
web.
3.4
Upper and lower connections of side frames of single side bulk carriers
3.4.1
The section moduli of the:・ side shell and hopper tank longitudinals that support the lower connecting brackets,・ side shell and topside tank longitudinals that support the upper connecting brackets
are to be such that the following relationship is separately satisfied for each lower and upper connecting bracket(see also Ch 3, Sec 6, Fig 22):
( p S + pW )l 2 l 12³awdån i i T
16 RY
where:n: Number of the longitudinal stiffeners of side shell and hopper / topside tank that support the lower /upper end connecting bracket of the side frame, as applicable: Net section modulus, in cm3, of the i-th longitudinal stiffener of the side shell or hopper / topsidewitank that support the lower / upper end connecting bracket of the side frame, as applicable: Distance, in m, of the above i-th longitudinal stiffener from the intersection point of the side shelldiand hopper /topside tank
: Spacing, in m, of transverse supporting webs in hopper / topside tank, as applicablel1: Lowest value of equivalent yield stress, in N/mm2, among the materials of the longitudinal stiffeners
Ryof side shell and hopper / topside tanks that support the lower / upper end connecting bracket of theside frameaT: Coefficient taken equal to:aT = 150 for the longitudinal stiffeners supporting the lower connecting brackets
aT = 75 for the longitudinal stiffeners supporting the upper connecting bracketsl: Side frame span, in m, as defined in 3.3.1.
pS , pW : Still water and wave pressures as those for the side frame.
3.4.2
The net connection area, Ai, in cm2, of the bracket to the i-th longitudinal stiffener supporting the bracket is to beobtained from the following formula:
ws k
Ai = 0.4 i2 bkt
l 1 k lg , iwhere:
wi : Net section modulus, in cm3, of the i-th longitudinal stiffener of the side or sloped bulkheads that
support the lower or the upper end connecting bracket of the side frame, as applicable: As defined in 3.4.1
l1
kbkt : Material factor for the bracket
klg,i : Material factor for the i-th longitudinal stiffener.
s: Frame spacing, in m.

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3.5
Strength criteria for multi-span ordinary stiffeners
3.5.1 Checking criteria
The maximum normal stress s and shear stress t in a multi-span ordinary stiffener, calculated according to 3.5.2,
are to comply with the formulae in Table 6.
Table 6Checking criteria for multi-span ordinary stiffeners

Condition

IntactFloodedTesting

Normal stresss £ lS RYs £ alS RY

s £ 1.05RY

Shear stresst £ tat £ at at £ 1.05t a

where:

lS : Coefficient defined in 3.2.3
a : Coefficient defined in 3.2.5
3.5.2 Multi-span ordinary stiffeners
The maximum normal stress s and shear stress t in a multi-span ordinary stiffener are to be determined by a direct
calculation taking into account:・ the distribution of still water and wave pressure and forces, if any
・ the number and position of intermediate supports (decks, girders, etc.)
・ the condition of fixity at the ends of the stiffener and at intermediate supports
・ the geometrical characteristics of the stiffener on the intermediate spans.
3.6

Scantlings of transverse vertically corrugated watertight bulkheads separating cargo holds forflooded conditions
3.6.1 Bending capacity and shear capacity of the corrugations of transverse vertically corrugated watertightbulkheads separating cargo holds
The bending capacity and the shear capacity of the corrugations of watertight bulkheads between separating cargoholds are to comply with the following formulae:
M
0.5WLE + WM ³
103
0.95 ReH
ReH
2
where:
M : Bending moment in a corrugation, to be obtained, in kN.m, from the following formula:
M = FlC / 8
F : Force FF or resultant force, in kN, to be calculated according to Ch 4, Sec 6, 3.3.6 and 3.3.7,
respectively
lC : Span of the corrugations, in m, to be obtained according to 3.6.2
WLE : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the lower end of thecorrugations according to 3.6.2, without being taken greater than the value obtained from the following
formula:æ Q hG - 0.5hG2 sC pG ö 3
WLE , M = WG + çç
10
ReH
è
ø
WG : Net section modulus, in cm3, of one half pitch corrugation, to be calculated in way of the upper end of
shedder or gusset plates, as applicable, according to 3.6.2
Q : Shear force at the lower end of a corrugation, to be obtained, in kN, from the following formula:Q = 0.8Ft£hG : Height, in m, of shedders or gusset plates, as applicable (see Fig. 11 to Fig. 15)
pG : Pressure pF or resultant pressure p, in kN/m2, to be calculated in way of the middle of the shedders or
gusset plates, as applicable, according to Ch 4, Sec 6, 3.3.6 and 3.3.7, respectively
sC : Spacing of the corrugations, in m, to be taken according to Ch 3, Sec 6, Fig.28－196－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

WM : Net section modulus, in cm3, of one half pitch corrugation, to be calculated at the mid-span ofcorrugations according to 3.6.2, without being taken greater than 1.15WLE
t : Shear stress in the corrugation, in N/mm2, to be obtained from the following formula:Qt = 10Ash
Ash : Shear area, in cm2, calculated according to the followings.
The shear area is to be reduced in order to account for possible non-perpendicular between thecorrugation webs and flanges. In general, the reduced shear area may be obtained by multiplying the
web sectional area by (sin ), being the angle between the web and the flange (see Ch 3, Sec 6, Fig.
28). The actual net section modulus of corrugations is to be calculated according to 3.6.2. The net
section modulus of the corrugations upper part of the bulkhead, as defined in Sec 1, Fig. 5, is to be notless than 75% of that of the middle part complying with this requirement and Sec 1, 3.2.1, corrected
for different minimum yield stresses.
3.6.2 Net Section modulus at the lower end of corrugationsa) The net section modulus at the lower end of corrugations (Fig. 11 to Fig. 15) is to be calculated with thecompression flange having an effective flange width bef not larger than that indicated in Ch 3, Sec 6, 10.4.10b) Webs not supported by local brackets
Except in case e), if the corrugation webs are not supported by local brackets below the stool top plate (or below
the inner bottom) in the lower part, the section modulus of the corrugations is to be calculated considering thecorrugation webs 30% effective.
c) Effective shedder plates
Provided that effective shedder plates, as defined in Ch 3, Sec 6, 10.4.11 are fitted (see Fig. 11 and Fig. 12),
when calculating the section modulus of corrugations at the lower end (cross sections 1 in Fig. 11 and Fig. 12),the net area of flange plates may be increased by the value obtained, in cm2, from the following formula:
I SH = 2.5a t f t SHd)without being taken greater than 2.5at f ,where:
a : Width, in m, of the corrugation flange (see Ch 3, Sec 6, Fig. 28)
tSH : Net shedder plate thickness, in mm
tf : Net flange thickness, in mm.
Effective gusset plates
Provided that effective gusset plates, as defined in Ch 3, Sec 6, 10.4.12, are fitted (see Fig. 13 to Fig. 15), whencalculating the net section modulus of corrugations at the lower end (cross-sections 1 in Fig. 13 to Fig. 15), thearea of flange plates may be increased by the value obtained, in cm2, from the following formula:
I G = 7 hG t f

where:
hG : Height, in m, of gusset plates (see Fig. 13 to Fig. 15), to be taken not greater than (10/7) SGU.
SGU : Width, in m, of gusset plates.
tf : Net flange thickness, in mm.
e) Sloping stool top plate
If the corrugation webs are welded to a sloping stool top plate which has an angle not less than 45 with thehorizontal plane, the section modulus of the corrugations may be calculated considering the corrugation webs
fully effective. For angles less than 45 , the effectiveness of the web may be obtained by linear interpolation
between 30% for 0 and 100% for 45 .
Where effective gusset plates are fitted, when calculating the net section modulus of corrugations the net area offlange plates may be increased as specified in d) above. No credit may be given to shedder plates only.
3.6.3 Stiffeners in lower stool and upper stool
The net section modulus of stiffeners in lower stool and upper stool is to be greater of the values obtained from thefollowing formula or required by 3.2.5.
psl 2
10 3
w=
16al s RY
where:－197－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2): Pressure, in kN/m2, as defined in Ch 4 Sec 6, 3.3.7.
a and lS : defined in 3.2.5.
Fig. 11Symmetrical shedder platespshedder platehG①
lower stool

Fig. 12

Asymmetrical shedder plates

shedder platehG①
lower stool

Fig. 13Symmetrical gusset/shedder plates

gusset platehG①
lower stool－198－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

Fig. 14

Asymmetrical gusset/shedder plates

gusset platehG①
lower stool

Fig. 15①

Asymmetrical gusset/shedder plateshG==lower stool4.

Web stiffeners of primary supporting members

4.1
Net scantlings
4.1.1
Where primary supporting member web stiffeners are welded to ordinary stiffener face plates, their net sectional
area at the web stiffener mid-height is to be not less than the value obtained, in cm2, from the following formula:A = 0.1k1 psl
where:
k1 : Coefficient depending on the web connection with the ordinary stiffener, to be taken as:
for connections without collar plate (see Ch 3, Sec 6, Fig 8)
k1 = 0.30
k1 = 0.225
for connections with a collar plate (see Ch 3, Sec 6, Fig 9)
for connections with one or two large collar plates (see Ch 3, Sec 6, Fig 10 and 11)
k1 = 0.20
p : Pressure, in kN/m2, acting on the ordinary stiffener.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

4.1.2
The net section modulus of web stiffeners of non-watertight primary supporting members is to be not less than thevalue obtained, in cm3, from the following formula:w = 2.5s 2 t S S2
where:
s : Length, in m, of web stiffenerst: Web net thickness, in mm, of the primary supporting member
SS : Spacing, in m, of web stiffeners.
4.1.3 Connection ends of web stiffeners
Where the web stiffeners of primary supporting members are welded to ordinary stiffener face plates, the stress atends of web stiffeners of primary supporting members in water ballast tanks, in N/mm2, is to comply with thefollowing formula when no bracket is fitted:s £ 175
where:
Ds
s = K con K longi K stiffcos q
K con : Coefficient considering stress concentration, taken equal to:
K con = 3.5
for stiffeners in the double bottom or double side space (see Fig. 8)
K con = 4.0
for other cases (e.g. hopper tank, top side tank, etc.) (see Fig. 8)
K longi : Coefficient considering shape of cross section of the longitudinal, taken equal to:
K longi = 1.0

for symmetrical profile of stiffener (e.g. T-section, flat bar)

K longi = 1.3

for asymmetrical profile of stiffener (e.g. angle section, bulb profile)K stiff : Coefficient considering the shape of the end of the stiffener, taken equal to:
K stiff = 1.0

for standard shape of the end of the stiffener (see Fig. 9)

K stiff = 0.8

for the improved shape of the end of the stiffener (see Fig. 9)q
Ds: As given in Fig. 10: Stress range, in N/mm2, transferred from longitudinals into the end of web stiffener, as obtained
from the following formula:2W
Ds =0.322h' [( Aw1 l 1 ) + ( Aw 2 l 2 )] + As 0Wp

: Dynamic load, in N, as obtained from the following formula:W = 1000(l - 0.5s )sp: Maximum inertial pressure due to liquid in the considered compartment where the web stiffener isllocated according to Ch 4, Sec 6, 2.2.1, in kN/m2, of the probability level of 10-4. , calculated at
mid-span of the ordinary stiffener: Span of the longitudinal, in ms
: Spacing of the longitudinal, in m
As 0 , Aw1 , Aw 2 : Geometric parameters as given in Fig. 10, in mm2
l1 , l 2: Geometric parameters as given in Fig. 10, in mm: As obtained from following formula, in mm:
h' = h s + h0 'hs
: As given in Fig. 10, in mm
h0 ': As obtained from the following formula, in mm
h0 ' = 0.636b'
for b' £ 150
h0 ' = 0.216b'+63
for 150 < b'h'b'

: Smallest breadth at the end of the web stiffener, in mm, as shown in Fig. 10－200－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 2)

Fig.8

Web stiffeners fitted on primary supporting members

Stiffener

Stiffener

X-X

Fig. 9Y-Y

Shape of the end of the web stiffener

bs

bs

bs

b'
b'
Standard shapes of the end of
the stiffenerFig. 10b'
Shape of the end of thestiffener considering fatigue
strength in comparison withthe standard shape

Definitions of geometric parametersNote:ts : net thickness of the web stiffener, in mm.
tw : net thickness of the collar plate, in mm.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

Section 3

BUCKLING & ULTIMATE STRENGTH OF ORDINARYSTIFFENERS AND STIFFENED PANELS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
In this section, compressive and shear stresses are to be taken positive, tension stresses are to be taken negative.
a : Length in mm of the longer side of the partial plate field in general or length in mm of the side of the partial
plate field according Table 2, BLC 3 10
b : Length in mm of the shorter side of the partial plate field in general or length in mm of the side of the partial
plate field according Table 2, BLC 3 10
a : Aspect ratio of elementary plate panel, taken equal to:aa=bn: Number of elementary plate panel breadths within the partial or total plate panel
Fig. 1

General arrangement of panel
Partial fieldn·bSingle field

bm

b

am

y
x

a

Transverse stiffenerLong. stiffener

Longitudinal ：stiffener in the direction of the length aTransverse ：stiffener in the direction of the breath b

t

sn
tSF
sx
sy
t
l

:
:
:
:
:
:
:

Net plate thickness, in mm
Normal stress resulting from hull girder bending, in N/mm2
Shear stress induced by the shear forces as defined in 2.1.3, in N/mm2
Membrane stress in x-direction, in N/mm2
Membrane stress in y-direction, in N/mm2
Shear stress in the x-y plane, in N/mm2
Reference degree of slenderness, taken equal to:

l=

ReH
Ks e

K : Buckling factor according to Table 2 and Table 3
Reference stress, to be the following for BLC 1 and 2:
s e : Reference stress, taken equal to:2

æ t ös e = 0 .9 E çè b¢ øb ¢ : Shorter side of elementary plate panel
Reference stress, to be the following for BLC 3 through 10:
s e : Reference stress, taken equal to:－202－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)ætös e = 0.9 E ç
èbø

y

S

F1

2

: Edge stress ratio taken equal to:y = s 2 / s1
where:
s1 : maximum compressive stresss2 : minimum compressive stress or tensile stress: Safety factor, taken equal to:
S = 1.0
except for the case mentioned below
S = 1.1
for structures which are exclusively exposed to local loads (e.g. hatch covers, foundations)S = 1.15 for the ultimate strength in lateral buckling mode of longitudinal and transverse ordinary stiffenersof the hatchway coamings, sloping plating of the topside tanks and hopper tanks, inner bottom,
inner side if any, side shell of single side skin construction and top and bottom stools of transverse
bulkheads, assessed according to 4.2.
For constructions of aluminium alloys the safety factors are to be increased in each case by 0.1: Correction factor for boundary condition of stiffeners on the longer side of elementary plate panels according
to Table 1. If the clamping is unequal on the longitudinal sides of the panel, the minimum value of theappropriate F1-parameter has to be used.
Table 1

Correction factor F1
F1(2)

Stiffeners sniped at both ends

Edge stiffener

1.00
1.05

Flat bar

Guidance values where both ends

1.10

Bulb section

are effectively connected to

1.21

Angle and tee-sections

adjacent structures(1)1.30

Girders of high rigidity(e.g. bottom transverses)(1) Exact values may be determined by direct calculations.
(2) An average value of F1 is to be used for plate panels having different edge
stiffeners.

1.

General1.1
1.1.1
The requirements of this Section apply for the buckling check of structural members subjected to compressive
stresses, shear stresses and lateral pressure.
1.1.2
The buckling checks have to be performed for the following elements:(a) according to requirements of 2, 3 and 4 and for all load cases as defined in Ch 4, Sec 4 in intact condition:
・ elementary plate panels and ordinary stiffeners in a hull transverse section analysis,・ elementary plate panels modeled in FEM as requested in Ch 7.
(b) according to requirements of 6 and only in flooded condition:
・ transverse vertically corrugated watertight bulkheads.
1.1.3
The boundary condition for elementary plate panels are to be considered as simply supported. If the boundary
condition differs significantly from simple support, more appropriate boundary condition can be applied according tocases 3, 4 and 7 to 10 of Table 2.

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2.

Application

2.1
Load model for hull transverse section analysis
2.1.1 General
The structural members at a considered hull transverse section are to be checked for buckling criteria under the
combination of:・ the normal stress sn resulting from hull girder bending, as defined in 2.1.2
・ the shear stress tSF as defined in 2.1.3
・ the lateral pressure in intact condition applied on the members as the case may be.
The lateral pressures and hull girder loads are to be calculated, for the probability level of 10-8, in the mutually
exclusive load cases H1, H2, F1, F2, R1, R2, P1 and P2, as defined in Ch 4, Sec 4.
2.1.2 Normal stress sn
The normal stress sn to be considered for each of the mutually exclusive load cases as referred in 2.1.1 is the
maximum compressive stress on the considered structural member according to the formulas given in Ch 6, Sec 1,
3.1.5 and Ch 6, Sec 2, 3.1.5, respectively for elementary plate panels and ordinary stiffeners.
For transverse ordinary stiffeners, the normal stress sn for each of the mutually exclusive load cases is the
maximum compressive stress calculated at each end.
2.1.3 Shear stress
The shear stress tSF to be considered for each of the mutually exclusive load cases as referred in 2.1.1 is the shear
stress induced by the shear forces, in kN, equal to:
Q = Q SW + C QW QWVwhere:QSW : Design still water shear force in intact condition, in kN, at the hull transverse section considered,defined in Ch 4, Sec 3, 2.3
QWV : Vertical wave shear force in intact condition, in kN, at the hull transverse section considered, definedin Ch 4, Sec 3, 3.2
CQW : Load combination factor as defined in Ch 4, Sec 4, Table 3
If the design still water shear force is not available at preliminary design stage, the following default value, in kN,
may be used:
QSW0 = 30 C LCSR-B B (CB + 0.7)10-2
2.1.4 Lateral pressure
The lateral pressure to be considered for the buckling check is defined in Ch 6, Sec 1, 3.1 for curved plate panel
and in Ch 6, Sec 2, 3.1 for ordinary stiffeners.
The load calculation point for the curved plate panel is located at mid distance of the curved plate panel extremities
along the curve.
The load calculation point of ordinary stiffeners is defined in Ch 6, Sec 2, 1.4
2.2
Application
2.2.1
Application of the buckling and ultimate strength criterion is described in App 1.

－204－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

Table 2
Buckling-

Edge stress

Load Case

ratio

Buckling and reduction factors for plane elementary plate panels
Asp. ratio
a = ab

Buckling factor K

Reduction factor

1

t

b

y·sx

K=

1³y ³ 0

sx

sx

a·b

y·sx

0 > y > -1

a ³1

8.4
y + 1.1

kx =1

K = 7.63 - y (6.26 - 10y )

lc =
2

2

t
sy

a ³1

2

1 ö
æ
K = F1 ç1 + 2
è a ø

2.1

(y + 1.1)

b

y·sy

sy

0.88 ö
c æç
1+ 1ç
2è
c ø

K = (1 - y ) 5.975

y £ -1

1³y ³ 0for l £ lc

æ 1 0.22 ö
k x = cç - 2
for l > lcl øèlc = (1.25 - 0.12y ) £ 1.25

y·sy
a·b

1 £ a £ 1.5

2
éæ
1 ö 2.1(1 + y )K = F1 êç1 + 2
1. 1
êëè a øyù
- 2 (13.9 - 10y )ú
aûæ 1 R + F 2 (H - R ) ö
k y = cçç l2øèl
c = (1.25 - 0.12y ) £ 1.25

æ lö
R = lç 1 è cøR = 0.22lc =0 > y > -1

2
éæ1 ö 2.1(1 + y )K = F1 êç1 + 2
1. 1
êëè a øa > 1.5-y(5.87 + 1.87a 2
a2
8.6
ù+ 2 - 10y ) úaû

for l < lc
for l ³ lc

0.88 ö
c æç
1+ 1ç
2è
c ø

K
æ
ö
-1
ç
0
.
91
F = ç1 c1 ³ 0
2
ç
lp
ç
è
ø

l p 2 = l2 - 0.5

2

for 1 £ l p £ 3

c1 = 1 , for s y due to direct loads
æ F ö
c1 = çç1 - 1 ³ 0 , for s y due toa øè1£ a £
3(1 - y )4

æ1 -y öK = F1 çè a ø

bending (in general)
c1 = 0 , for s y due to bending in

2

5.975

extreme

load

cases

(e.g.

bulkheads)
H = l-y £ -1a>3(1 - y )4

éæ 1 - y ö
K = F1 êçëêè a ø2

3.96754

æ 1 -y ö+ 0.5375 ç+1.87 ]
è a øExplanations for boundary conditions

-----

2l

cæç T + T 2 - 4 öèø
14 1
T = l++
15 l 3³R

plate edge freeplate edge simply supported
plate edge clamped

Note: The load cases as listed in Table 2 are general cases. Each stress component ( sx, sy) is to be understood in a local
coordinates.

－205－

wt.

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

3
sx

y·sx

1³y ³ 0

t

b

sx

a·b

y·sx

a >0

1 ö
æ
4ç 0.425 + 2a øèK=
3y + 11 öæK = 4ç 0.425 + 2 (1 + y ) - 5y (1 - 3.42y )aèø

0 > y ³ -1

for l £ 0.7

kx =1

1
kx = 2l + 0,51

4

b

t
sx

for l > 0.7

y·sx

y·sx

1 ³ y ³ -1

a >0

sx

a·b

5

K = Kt

t
t

t

b

t

===

t

a·b

4 ù
é
K t = ê5.34 + 2 úa ûë0 < a <1

5.34 ù
éK t = ê4 + 2 úa ûëK¢ = K
according to load case 5
r = Reductions factor

db

t
b

t

t

t

===

a ³ 1.64

K = 1.28

kx =1

a < 1.64

K=

1

kx =

b

a·b

8
sx

sx

b

t

2
3

K = 6.97

a<

2
3

K=

a·b

sx

sx

b

t

===

a·b

10
sx
t

b

sx

a·b

===

a

+ 0.56 + 0.13a 2
2

a³
===

9

l

for l > 0.84

æ d a öæ d b ö
çç1 ç1 a øçè
b ø
è
d
d
with a £ 0.7 and b £ 0.7
a
b

sx
===

kt =

0.84

r =

a·b

t

for l £ 0.84

kt = 1

K = K¢r

da

7
sx

3

a ³1

6

t

1 ö 3 -yæ
K = ç 0.425 + 2aèø 2

for l £ 0.7

1
l2 + 0.51
for l > 0.7

1+ 2.5 + 5a 2
a2

a ³4

K =4

4 > a >1

é4-a ù
K = 4+ê
ú
ë 3 û

a £1

K=

a³4

K = 6.97

4 > a >1

é4 -a ùK = 6.97 + ê
ú
ë 3 û

a £1

K=

4

a2

kx =1

4

for l £ 0.83

é 1 0.22 ù
k x = 1.13ê - 2 ú
l û
ël

2.74

+ 2.07 + 0.67a 2

for l > 0.83

4

3.1

4
+ 2.07 + 4a 2
a2

Explanations for boundary conditions-----

plate edge freeplate edge simply supported
plate edge clamped

Note: The load cases as listed in Table 2 are general cases. Each stress component ( sx, sy) is to be understood in a local
coordinates.

－206－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

Buckling and reduction factor for curved plate panel with R/t £ 25001

Table 3

Aspect ratiobR

BucklingLoad Case

Buckling factor K

Reduction factor

1a
b

sx

b
R
£ 1.63
R
t

K=

b

+3

Rt

(R t )0.175
b 0.35Rtkx =1
k x = 1.274 - 0.686 l

sx

1b

kx =

with

b

p ·R
sx = e
t
R
t

pe

b
R
> 1.63Rt

K = 0.3

æ R2 ö
b2
çç
2
.
25
+
R2
è bt ø

b
R
£ 0.5
R
t

K = 1+

2 b2
3 Rt

0.65

for l £ 0.4 2
for 0.4 < l £ 1.2
for l > 1.2l22

pe = external pressure in[N/mm2]2bsyR

K = 0.267

t
sy

b
R
> 0.5
R
t

3

b
£
R

b
sx
R
t

sx

b
>
R

K=

R

t

k y = 1.233 - 0.933 l

t ù
ú
R ûú

0.6 b
Rt

æ R2 ö
b
K = 0.3 2 + 0.291çç
Rè bt ø

Rt

K = Kt

b
R
£ 8.7
R
t

as in load case 1a2

kt = 1k t = 1.274 - 0.686 l

0 .5

t

kt =
K t = 0.28

Explanations for boundary conditions

for l > 1.5

k y = 0.2 / l

3é
0.67 b 3 ù
K t = ê28.3 + 1.5 1.5 ú
R t û
ë

b
R
> 8.7
R
t

for 1 < l £ 1.5

2

k y = 0.3 / l
b2
Rt

for 0.25 < l £ 1

3

Rt
Rt
- 0.3 2
b
b

+

2

4
b

b2 é
b
ê3 R t ëê
R

³ 0.4

R
t

for l £ 0.25 2

ky =1

b

2

0.65

l2

for l £ 0.4
for 0.4 < l £ 1.2
for l > 1.2

R Rt

-----

plate edge freeplate edge simply supported
plate edge clamped1

For curved plate fields with a very large radius the -value need not to be taken less than for the expanded plane field2

For curved single fields, e.g. bilge strake, which are located within plane partial or total fields, the reduction factor
may taken as follow:
Load case 1b: k x =

0.8
2

l

£ 1.0

Load case 2: k y =

－207－

0.65

l2

£ 1.0

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

3.

Buckling criteria of elementary plate panels

3.1
Plates
3.1.1 General
The net thickness of the elementary plate panel is to comply with the following:t ³ b / 100
The verification of an elementary plate panel in a transverse section analysis is to be carried out according to 3.1.2.
It is to be performed for the two different following combinations of stresses:
・ stress combination 1: 100% of the normal stress as defined in 2.1.2 and 70% of the shear stress as defined in
2.1.3
・ stress combination 2: 70% of the normal stress as defined in 2.1.2 and 100% of the shear stress as defined in
2.1.3.
The verification of elementary plate panel in a FEM analysis is to be carried out according to 3.2.
3.1.2 Verification of elementary plate panel in a transverse section analysis
Each elementary plate panel is to comply with the following criteria, taking into account the loads defined in 2.1:
・ longitudinally framed platinge1

e3

æt S 3öæ sx S ö
ç
+ç
£ 1.0
çk R
ç kt ReH
è x eH ø
è
ø
e1

・

e3

æt S 3öæ sx S ö
ç
+ç
£ 1.0
çk R
ç kt ReH
è x eH øèøtransversely framed platinge2

for stress combination 2 with sx = 0.7 sn and t = tSF

e3

æ sy S ö
æ t S 3öç
£ 1 .0+çç k y ReHç kt ReH
ø
è
ø
è
e2

for stress combination 1 with sx = sn and t = 0.7 tSF

for stress combination 1 with sy = sn and t = 0.7 tSF

e3

æ sy S ö
æ t S 3öç
£ 1 .0+çç k y ReHç kt ReHøèøè

for stress combination 2 with sy = 0.7 sn and t = tSF

Each term of the above conditions must be less than 1.0.
The reduction factors kx and ky are given in Table 2 and/or Table 3.
The coefficients e1, e2 and e3 are defined in Table 4. For the determination of e3, ky is to be taken equal to 1 incase of longitudinally framed plating and kx is to be taken equal to 1 in case of transversely framed plating.
3.2
Verification of elementary plate panel within FEM analysis
3.2.1 General
The buckling check of the elementary plate panel is to be performed under the loads defined in 3.2.2, according to
the requirements of 3.
The determination of the buckling and reduction factors is made for each relevant case of Table 2 according to thestresses calculated in 3.2.2 loading the considered elementary plate panel.
3.2.2 Stresses
For the buckling check, the buckling stresses are to be determined according to Table 2 and Table 3 including
their stress ratio for the loading conditions required in Ch 4, Sec 7 and according to the requirements of Ch 7.
3.2.3 Poisson effectStresses derived with superimposed or direct method have to be reduced for buckling assessment because of the
Poisson effect, which is taken into consideration in both analysis methods. The correction has to be carried out after
summation of stresses due to local and global loads.
Both stresses s *x and s *y are to be compressive stresses, in order to apply the stress reduction according to thefollowing formulae:s x = (s x* - 0.3s *y ) / 0.91

s y = (s *y - 0.3s x* ) / 0.91
where:－208－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)s x* , s *y : Stresses containing the Poisson effect
Where compressive stress fulfils the condition s *y < 0.3s x* , then s y = 0 and s x = s *x
Where compressive stress fulfils the condition s x* < 0.3s *y , then s x = 0 and s y = s *y
3.2.4 Checking Criteria
Each elementary plate panel is to comply with the following criteria, taking into account the loads defined in 2.1:
e2

e3

e1
æ sy S öæ s xs y S 2 ö æ t S 3 öæ sx S ö
ç
+ç
+ç
£ 1.0
- Bç
2
çk R
ç
ç
ç
k
R
R
eH
è x eH øø è kt ReH øèè y eH ø
In addition, each compressive stress sx and sy, and the shear stress t are to comply with the following formulae:e1

æ sx S öç£ 1 .0çk R
è x eH øæ sy S öçç k y ReH
è
ø

e2

£ 1.0
e3

æt S 3öç£ 1 .0ç kt ReHèø
The reduction factors k x , k y and k t are given in Table 2 and/or Table 3.

・ where s x £ 0 (tensile stress), k x = 1.0.
・ where s y £ 0 (tensile stress), k y = 1.0.
The coefficients e1, e2 and e3 as well as the factor B are defined in Table 4.
Table 4
Exponents e1

Coefficients e1, e2, e3 and factor B

e3

and factor B

Plate panel
planecurved

4
x

1.25

e1

1+ k

e2

1 + k y4e3Bsx and sy positive(compressive stress)Bsx or sy negative(tensile stress)

1.25
2

1 + k x k y kt

2.0

(k k )

0

1

-

5

x

y

3.3
Webs and flanges
3.3.1
For non-stiffened webs and flanges of sections and girders proof of sufficient buckling strength as for elementary
plate panels is to be provided according to 3.1.
4.

Buckling criteria of partial and total panels

4.1
Longitudinal and transverse stiffeners
4.1.1
In a hull transverse section analysis, the longitudinal and transverse ordinary stiffeners of partial and total plate
panels are to comply with the requirements of 4.2 and 4.3.

－209－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

4.2
Ultimate strength in lateral buckling mode
4.2.1 Checking criteria
The longitudinal and transverse ordinary stiffeners are to comply with the following criteria:s a + sb
S £1
R eH
s a : Uniformly distributed compressive stress, in N/mm2 in the direction of the stiffener axis.
s a = snfor longitudinal stiffeners
sa = 0for transverse stiffenerss b : Bending stress, in N/mm2, in the stiffener.
s b calculated as in 4.2.2 with sx = sn and t = tSF
4.2.2 Evaluation of the bending stress sb
The bending stress s b , in N/mm2, in the stiffeners is equal to:
M + M1sb = 0W st 10 3
with:
M0 : Bending moment, in N-mm, due to the deformation w of stiffener, taken equal to:pz w
M 0 = FKic f - pz()

with c f - p z > 0
M1 : Bending moment, in N-mm, due to the lateral load p, taken equal to:
pba 2
M1 =
for longitudinal stiffeners
24 10 32pa(n b )M1 =for transverse stiffeners, with n equal to 1 for ordinary transverse stiffeners.
8c S 10 3
Wst : Net section modulus of stiffener (longitudinal or transverse), in cm3, including effective width ofplating according to 5, taken equal to:・ if a lateral pressure is applied on the stiffener:
Wst is the net section modulus calculated at flange if the lateral pressure is applied on the same side
as the stiffener.
Wst is the net section modulus calculated at attached plate if the lateral pressure is applied on theside opposite to the stiffener.
Note: For stiffeners sniped at both ends, Wst is the net section modulus calculated at attached plate.
However, if M1 is larger than M0 and the lateral pressure is applied on the same side as the stiffener,
Wst is the net section modulus calculated at flange.
・ if no lateral pressure is applied on the stiffener:
Wst is the minimum net section modulus among those calculated at flange and attached plate
Note: For stiffeners sniped at both ends, Wst is the net section modulus calculated at attached plate.
cS : Factor accounting for the boundary conditions of the transverse stiffener
for simply supported stiffeners
cS = 1.0
for partially constraint stiffeners
cS = 2.0
p : Lateral load in kN/m2 , as defined in Ch 4, Sec5 and Ch 4, Sec 6 calculated at the load point as definedin Ch 6, Sec 2, 1.4
FKi : Ideal buckling force, in N, of the stiffener, taken equal to:p2
EI x 10 4for longitudinal stiffenersa2
p2
FKiy =
EI y 10 4
for transverse stiffeners
2(nb): Net moments of inertia, in cm4, of the longitudinal or transverse stiffener including effective width
FKix =

Ix, I yof attached plating according to 5. Ix and Iy are to comply with the following criteria:－210－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

bt 3
12 10 4at 3
Iy ³
12 10 4
: Nominal lateral load, in N/mm2, of the stiffener due to s x , s y and t
Ix ³

pz

2
ö
t æ æpbö
p zx = a ç s xl ç
for longitudinal stiffeners+ 2c y s y + t 1 2
b çè è a ø
ø
2
ö
Ay ö
t a æç
æ p a ö æç+p zy =
2c x s xl + s y ç12t
for transverse stiffeners+
1a çèè nb ø çè at a øøæA ö
s xl = s x çç1 + x
è b ta ø
ta : Net thickness offered of attached plate, in mm
c x , c y : Factor taking into account the stresses vertical to the stiffener's axis and distributed variable along

the stiffener's length taken equal to:
0.5 (1 + y )for 0 £ y £ 1
0.5
for y < 0
1-yAx , Ay : Net sectional area, in mm2, of the longitudinal or transverse stiffener respectively without attachedplatingéæ m m öùt1 = êt - t ReH E ç 21 + 22 ú ³ 0b ø ûú
èaëê

m1, m2 : Coefficients taken equal to:a³ 2.0 : m1 = 1.47 m2 = 0.49b
for longitudinal stiffeners:a< 2.0 : m1 = 1.96 m2 = 0.37b
for transverse stiffeners:a1.96³ 0.5 : m1 = 0.37 m2 = 2
nb
n
a
1.47
< 0.5 : m1 = 0.49 m2 = 2nbnw = w0 + w1

generallyw = w0 + w1

for stiffeners sniped at both ends, on which the same side lateral pressure as the stiffeneris applied.
w0 : Assumed imperfection, in mm, taken equal to:ab,, 10) for longitudinal stiffeners
w0 = min(250 250
a n b,, 10) for transverse stiffeners
w0 = min(250 250
For stiffeners sniped at both ends w0 must not be taken less than the distance from the midpoint of
attached plating to the neutral axis of the stiffener calculated with the effective width of its attachedplating.
w1 : Deformation of stiffener, in mm, at midpoint of stiffener span due to lateral load p. In case of
uniformly distributed load the following values for w1 may be used:
pba 4
w1 =
for longitudinal stiffeners
384 10 7 EI x
w1 =5ap(nb) 4
384 10 7 EI y c S2

for transverse stiffeners

c f : Elastic support provided by the stiffener, in N/mm2, taken equal to:－211－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

・ for longitudinal stiffenersp2
c f = FKix 2 (1 + c px )a1c px =
æ 12 10 4 I x ö-10.91çç
t 3b
è
ø
1+
c xa
c xa : Coefficient taken equal to :

é a 2b ùc xa = ê + ú
ë 2b a û2

for a ³ 2b2

é æ a ö2 ùc xa = ê1 + çúêë è 2b ø úû・ for transverse. stiffeners :for a < 2bp2
(1 + c py )(n b)2
1c py =
öæ 12 10 4 I y
0.91ç
-1
ç t 3aøè
1+c ya
c f = c S FKiyc ya : Coefficient taken equal to :
é nb 2a ù
c ya = ê + ú
ë 2a nb û2for nb ³ 2a2

é æ nb ö 2 ù
c ya = ê1 + ç
for nb < 2 aúêë è 2a ø úû
4.2.3 Equivalent criteria for longitudinal and transverse ordinary stiffeners not subjected to lateral pressure
Longitudinal and transverse ordinary stiffeners not subjected to lateral pressure, except for sniped stiffeners, areconsidered as complying with the requirement of 4.2.1 if their net moments of inertia Ix and Iy, in cm4, are not lessthan the value obtained by the following formula:öæç
p zx a 2 ç w0 hw
a2
Ix = 2 4+ 2
p 10 ç ReH - s
p E
ç
x
ø
è S
æ
ö
2
p zy (nb) 2 ç w0 hw
nb
(
)
ç
Iy =
+ 2
p 2 10 4 ç ReH - s
p E
ç
y
è S
ø

・ For longitudinal stiffener :・ For transverse stiffener :4.3
Torsional buckling
4.3.1 Longitudinal stiffeners
The longitudinal ordinary stiffeners are to comply with the following criteria:sxS£ 1 .0
k T R eHk T : Coefficient taken equal to:k T = 1.0 for lT £ 0.2
1
kT =for lT > 0.2
2
+
- lT2

(

= 0.5 1 + 0.21(lT - 0.2) + lT2

)

－212－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

lT : Reference degree of slenderness taken equal to:lT =s KiT =

ReH
s KiT

2
2
ö
E æç p I w 10
e + 0.385I T
2
ç
IP è
a
ø

, in N/mm2

I P : Net polar moment of inertia of the stiffener, in cm4, defined in Table 5, and related to the point C asshown in Fig. 2
I T : Net St. Venant's moment of inertia of the stiffener, in cm4, defined in Table 5,
I w : Net sectorial moment of inertia of the stiffener, in cm6, defined in Table 5, related to the point C aseshown in Fig. 2: Degree of fixation taken equal to:e = 1 + 10 -3a4ö
3 4 æbp I w çç 3 + 4h w 3
3t w ø
4
è t

Aw : Net web area equal to: Aw = h w t w

A f : Net flange area equal to: A f = b f t f

e f = hw +tf
2

, in mmFig. 2

Table 5
ProfileFlat bar

Sections with bulb
or flange

Dimensions of stiffeners

Moments of inertia

IP

IT

Iw

3
w w

hwt w3 æt ö
ç1 - 0.63 w
4 ç
3 10 è
hw ø

hw3 t w3
36 10 6hwt w3 æt ö
ç1 - 0.63 w
4 ç
3 10 è
hw øfor bulb and angle sections:A f e 2f b 2f æ A f + 2.6 Aw öç
12 10 6 çè A f + Aw øht
3 10 4

öæ Aw hw2
çç+ A f e 2f 10 - 4
ø
è 3

+
3
f f

æ
t ö
ç1 - 0.63 f
3 10 çè
bf øbt

4

for tee-sections
b3f t f e 2f
12 1064.3.2 Transverse stiffeners
Transverse stiffeners loaded by axial compressive stresses and which are not supported by longitudinal stiffeners
are to comply with the requirements of 4.3.1 analogously.
5.

Effective width of attached plating

5.1
Ordinary stiffeners
5.1.1
The effective width of attached plating of ordinary stiffeners is determined by the following formulae (see also Fig.
1):
－213－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)

・ for longitudinal stiffeners:

bm = min(k x b, k s s)・ for transverse stiffeners:

a m = min(k y a, k s s )where:
32

æ l eff öæ l eff öæ l eff ö
k s = 0.0035 çç- 0.0056 , to be taken not greater than 1.0- 0.0673 çç+ 0.4422 çç
è s ø
è s ø
è s ø
s : Spacing of the stiffener, in mm
leff : Value taken as follows:
・ for longitudinal stiffeners:
if simply supported at both ends
leff = aleff = 0.6a if fixed at both ends
・ for transverse stiffeners:
if simply supported at both ends
leff = bleff = 0.6b if fixed at both ends

5.2
Primary supporting members
The effective width e m' of stiffened flange plates of primary supporting members may be determined as describedin (a) and (b), with the notations:e : Width of plating supported, in mm, measured from centre to centre of the adjacent unsupported fields
em : Effective width, in mm, of attached plating of primary supporting member according to Table 6 considering thetype of loading (special calculations may be required for determining the effective width of one-sided or
non-symmetrical flanges).
em1 is to be applied where primary supporting members are loaded by uniformly distributed loads or else by notless than 6 equally spaced single loads.
em2 is to be applied where primary supporting members are loaded by 3 or less single loads.
Stiffening parallel to web of the primary supporting member (see Fig. 3)
Fig. 3

Stiffening parallel to web
e
em
em'

sx,em(y)sx,em'(y)

a)

bm

bm

b

b

b

b

y

b < eme m' = n bm

n : Integral number of the stiffener spacing b inside the effective width em, taken equal to:æe ö
n = int çç m
è b ø

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 3)b)

Stiffening perpendicular to web of the primary supporting member (see Fig. 4)
Fig. 4

Stiffening perpendicular to web
e
em

e

sx2

sx(y)

sx1

em'

am

a

y

a ³ eme m' = na m < e mem, to be taken not greater than 1.0a
For b ³ e m or a < e m respectively, b and a must be exchanged.
n = 2.7

Table 6

Effective Width of attached plating

l/e

0

1

2

3

4

5

6

7

³8

em1 /e

0

0.36

0.64

0.82

0.91

0.96

0.98

1.00

1.00

em2 /e

0

0.20

0.37

0.52

0.65

0.75

0.84

0.89

0.90

Intermediate values may be obtained by direct interpolation.
l : Length between zero-points of bending moment curve, i.e. unsupported span in case of simply supported girders
and 0.6 times the unsupported span in case of constraint of both ends of girder

6.

Transverse vertically corrugated watertight bulkhead in flooded conditions

6.1
General6.1.1 Shear buckling check of the bulkhead corrugation webs
The shear stress , calculated according to Ch 6, Sec 2, 3.6.1, is to comply with the following formula:t £ tC
where:
2
C : Critical shear buckling stress to be obtained, in N/mm , from the following formulae:R
tc = tEfort E £ eH2 3
ReH æç
ReH öR
fort E > eH1ç3 è 4 3t E ø
2 32
E : Euler shear buckling stress to be obtained, in N/mm , from the following formula:

tc =

2

æ t ö
t E = 0.9k t E çç w3
è 10 c ø
kt : Coefficient, to be taken equal to 6.34
tW : Net thickness, in mm, of the corrugation webs
c : Width, in m of the corrugation webs (see Ch 3, Sec 6, Fig. 28).

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

Section 4

PRIMARY SUPPORTING MEMBERS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Rule length LCSR-B, but to be taken not greater than 300 m: Net moment of inertia, in m4, of the hull transverse section about its horizontal neutral axis, to be calculated
according to Ch 5, Sec 1, 1.5, on gross offered thickness reduced by 0.5tC for all structural members: Net moment of inertia, in m4, of the hull transverse section about its vertical neutral axis, to be calculated
IZ
according to Ch 5, Sec 1, 1.5, on gross offered thickness reduced by 0.5tC for all structural membersN: Z co-ordinate with respect to the reference co-ordinate system defined in Ch 1, Sec 4, 4, in m, of the centreof gravity of the hull net transverse section defined in Ch 5, Sec 1, 1.2, considering gross offered thickness
reduced by 0.5tC for all structural members
pS, pW : Still water and wave pressure, in kN/m2, in intact conditions, defined in 2.1.2
sX: Normal stress, in N/mm2, defined in 2.1.5s: Spacing, in m, of primary supporting membersl: Span, in m, of primary supporting members, measured between the supporting members, see Ch 3, Sec 6,
5.3: Web height, in mm
hw: Net web thickness, in mmtwbf: Face plate width, in mm: Net face plate thickness, in mm
tf: Width, in m, of the plating attached to the member, for the yielding check, defined in Ch 3, Sec 6, 4.3
bpw: Net section modulus, in cm3, of the member, with an attached plating of width bp, to be calculated as
specified in Ch 3, Sec 6, 4.4
Ash : Net shear sectional area, in cm2, of the member, to be calculated as specified in Ch 3, Sec 6, 5.5m: Coefficient taken equal to 10
ta: Allowable shear stress, in N/mm2, taken equal to:ta = 0.4 RYk: Material factor, as defined in Ch 1, Sec 4, 2.2.1
x, y, z : X, Y and Z co-ordinates, in m, of the evaluation point with respect to the reference co-ordinate systemdefined in Ch 1, Sec 4
L2
IY

1.

General1.1

Application

1.1.1
The requirements of this Section apply to the strength check of pillars and primary supporting members, subjectedto lateral pressure and/or hull girder normal stresses for such members contributing to the hull girder longitudinalstrength.
The yielding check is also to be carried out for such members subjected to specific loads, such as concentrated
loads.
1.2
Primary supporting members for ships less than 150 m in length (LCSR-B)
1.2.1
For primary supporting members for ships having a length (LCSR-B) less than 150 m, the strength check of suchmembers is to be carried out according to the provisions specified in 2 and 4.

－216－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

1.2.2
Notwithstanding the above, the strength check of such members may be carried out by a direct strength assessment
deemed as appropriate by the Society.
1.3
Primary supporting members for ships of 150 m or more in length (LCSR-B)
1.3.1
For primary supporting members for ships having a length (LCSR-B) of 150 m or more, the direct strength analysis is
to be carried out according to the provisions specified in Ch 7, and the requirements in 4 are also to be complied with.
In addition, the primary supporting members for BC-A and BC-B ships are to comply with the requirements in 3.
1.4
Net scantlings
1.4.1
As specified in Ch 3, Sec 2, all scantlings referred to in this Section are net, i.e. they do not include any corrosion
addition.
The gross scantlings are obtained as specified in Ch 3, Sec 2, 3.
1.5
1.5.1

Minimum net thicknesses of webs of primary supporting members

The net thickness of the web of primary supporting members, in mm, is to be not less than 0.6 L2 .
1.6
Flooding check of primary supporting members
1.6.1 General
Flooding check of primary supporting members is to be carried out according to the requirements in 5.
2.

Scantling of primary supporting members for ships of less than 150 m in length (LCSR-B)

2.1
Load model
2.1.1 General
The still water and wave lateral loads induced by the sea and the various types of cargoes and ballast in intact
conditions are to be considered, depending on the location of the primary supporting members under considerationand the type of the compartments adjacent to it.
The wave lateral loads and hull girder loads are to be calculated, for the probability level of 10-8, in the mutually
exclusive load cases H1, H2, F1, F2, R1, R2, P1 and P2, as defined in Ch 4, Sec 4.
2.1.2 Lateral pressure in intact conditions
The lateral pressure in intact conditions is constituted by still water pressure and wave pressure.
Still water pressure (pS) includes:
・ the hydrostatic pressure, defined in Ch 4, Sec 5, 1・ the still water internal pressure, defined in Ch 4, Sec 6 for the various types of cargoes and for ballast.
Wave pressure (pW) includes for each load case H1, H2, F1, F2, R1, R2, P1 and P2:・ the hydrodynamic pressure, defined in Ch 4, Sec 5, 1・ the inertial pressure, defined in Ch 4, Sec 6 for the various types of cargoes and for ballast.
2.1.3 Elements of the outer shell
The still water and wave lateral pressures are to be calculated considering separately:・ the still water and wave external sea pressures・ the still water and wave internal pressure, considering the compartment adjacent to the outer shell as being
loadedIf the compartment adjacent to the outer shell is not intended to carry liquids, only the external sea pressures are to
be considered.
2.1.4 Elements other than those of the outer shell
The still water and wave lateral pressures to be considered as acting on an element which separates two adjacentcompartments are those obtained considering the two compartments individually loaded.

－217－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

2.1.5 Normal stresses
The normal stress to be considered for the strength check of primary supporting members contributing to the hull
girder longitudinal strength is the maximum value of sX between sagging and hogging conditions, when applicable,
obtained, in N/mm2, from the following formula:
é
ù
M
M
M
s X = êC SW SW ( z - N ) + CWV WV ( z - N ) - CWH WH y ú 10 -3
IZ
IY
IY
ëê
ûú
where:MSW : Permissible still water bending moments, in kN-m, in hogging or sagging as the case may be
MWV : Vertical wave bending moment, in kN-m, in hogging or sagging as the case may be, as defined in Ch
4, Sec 3
MWH : Horizontal wave bending moment, in kN-m, as defined in Ch 4, Sec 3
CSW : Combination factor for each load case H1, H2, F1, F2, R1, R2, P1 and P2 and defined in the Table 1
CWV, CWH : Combination factors defined in Ch 4, Sec 4, 2.2 for each load case H1, H2, F1, F2, R1, R2, P1
and P2 and given in the Table 1
Table 1
LC

Hogging
CSW

H1
H2

Combination factors CSW, CWV and CWH

CWV

Sagging
CWH

Not Applicable
1

F1

1

CSW

CWV

CWH

-1

-1

0

0

Not Applicable

Not Applicable

-1

-1

0

F2

1

1

0

Not Applicable

R1

1

0

1.2 -

TLC
TS

-1

0

1.2 -

R2

1

0

TLC
- 1.2
TS

-1

0

TLC
- 1.2
TS

P1

1

0.4 -

TLC
TS

0

-1

0.4 -

TLC
TS

0

P2

1

TLC
- 0.4
TS

0

-1

TLC
- 0.4
TS

0

TLC
TS

2.2
Center Girders and Side Girders
2.2.1 Net web thickness
The net thickness of girders in double bottom structure, in mm, is not to be less than the greatest of either of thevalue t1 to t3 specified in the followings according to each location:2
pS x - x c ìï
æ y ö üïç
t1 = C 1
1
4
where x - x c is less than 0.25l DB , x - x c is to be taken as(d 0 - d1 )t a íïî çè B DB ø ýïþ
0.25l DBt 2 = 1.75 3t3 =H 2 a 2t a
t1
¢
C1

C1¢¢a

k
where:p: Differential pressure given by the following formula in kN/m2:

p = ( p S , IB + pW , IB ) - ( p S , BM + pW , BM )p S , IB : Cargo or ballast pressure of inner bottom plating in still water, in kN/m2, as calculated at the centreof the double bottom structure under consideration, according to Ch 4, Sec 6－218－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

pW , IB : Cargo or ballast pressure of inner bottom plating due to inertia, in kN/m2, as calculated at the centreof the double bottom structure under consideration, according to Ch 4, Sec 6
p S , BM : External sea and ballast pressure of bottom plating in still water, in kN/m2, as calculated at the centreof the double bottom structure under consideration, according to Ch 4, Sec 5 and Ch 4, Sec 6
pW , BM : External sea and ballast pressure of bottom plating due to inertia, in kN/m2, as calculated at thecentre of the double bottom structure under consideration, according to Ch 4, Sec 5 and Ch 4, Sec 6
Distance between the centre of the two spaces adjacent to the centre or side girder underconsideration, in m
Depth of the centre or side girder under consideration, in m
Depth of the opening, if any, at the point under consideration, in m
Length of the double bottom, in m. Where stools are provided at transverse bulkheads, l DB may be

S

:

d0
d1
l DB

:
:
:

xc

taken as the distance between the toes.
: X co-ordinate, in m, of the centre of double bottom structure under consideration with respect to the

BDB
C1

reference co-ordinate system defined in Ch 1, Sec 4: Distance between the toes of hopper tanks at the midship part, in m, see Fig 3: Coefficient obtained from Table 2 depending on B DB / l DB . For intermediate values of B DB / l DB ,C 1 is to be obtained by linear interpolation

a

S1
C1¢

: Depth of girders at the point under consideration, in m. However, where horizontal stiffeners are
fitted on the girder, a is the distance from the horizontal stiffener under consideration to the bottom
shell plating or inner bottom plating, or the distance between the horizontal stiffeners underconsideration: Spacing, in m, of vertical ordinary stiffeners or floors: Coefficient obtained from Table 3 depending on S1 / a . For intermediate values of S1 / a , C1¢ isH

to be determined by linear interpolation: Value obtained from the following formulae:
・ where the girder is provided with an unreinforced opening :

f
a
C1¢¢

H = 1+ 0.5

fa

H = 1 .0・ In other cases:: Major diameter of the openings, in m
: The greater of a or S1 , in m.

: Coefficient obtained from Table 4 depending on S1 / a . For intermediate values of S1 / a , C1¢¢ isto be obtained by linear interpolation.
Table 2
BDB / l DB

0.4 and

C1

0.5

under

Coefficient C1
0.8

1.0

1.2

1.4

0.71

0.83

0.88

0.95

0.98

0.3 and

C1¢

64

under

C1¢¢

0.3 and
under

1.00

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

1.4 and over

38

25

19

15

12

10

9

8

7

Coefficient C1¢¢

Table 4S1aover

Coefficient C1¢

Table 3S1a

1.6 and

0.6

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

1.4

1.6 andoverCentre girder

4.4

5.4

6.3

7.1

7.7

8.2

8.6

8.9

9.3

9.6

9.7

Side girder

3.6

4.4

5.1

5.8

6.3

6.7

7.0

7.3

7.6

7.9

8.0

－219－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

2.3
Floors
2.3.1 Net web thickness
The net thickness of floors in the double bottom structure, in mm, is not to be less than the greatest of values t1 to t3
specified in the following according to each location:2
æ x - xc ö üï
pSBDB æ 2 y öìïç
t1 = C2ýí1 - 2çç
'(d0 - d1 )t a çè BDB
è l DB ø ïþøïî'where x - xc is less than 0.25l DB , x - xc is to be taken as 0.25l DB , and where y is less than BDB/4,'
y is to be taken as BDB/4

t2 = 1.75 3t3 =H 2 a 2t a
t1
C2¢

8.5S 2kwhere:S: Spacing of solid floors, in m
d 0 : Depth of the solid floor at the point under consideration in m
d 1 : Depth of the opening, if any, at the point under consideration in m'
B DB
: Distance between toes of hopper tanks at the position of the solid floor under consideration, in m

: Coefficient obtained from Table 5 depending on B DB / l DB . For intermediate values of B DB / l DB ,C 2 is to be obtained by linear interpolationp , BDB , x c , l DB : As defined in 2.2.1

C2

a

S1
C 2¢

H

: Depth of the solid floor at the point under consideration, in m. However, where horizontal stiffeners
are fitted on the floor, a is the distance from the horizontal stiffener under consideration to the bottom
shell plating or the inner bottom plating or the distance between the horizontal stiffeners underconsideration: Spacing, in m, of vertical ordinary stiffeners or girders: Coefficient given in Table 6 depending on S1 / d0 . For intermediate values of S1 / d0 , C 2¢ is to be
determined by linear interpolation.
: Value obtained from the following formulae:(a) where openings with reinforcement or no opening are provided on solid floors:i) where slots without reinforcement are provided:
H = 4.0

d2- 1.0 , without being taken less than 1.0
S1ii) where slots with reinforcement are provided: H = 1.0(b) where openings without reinforcement are provided on solid floors:i) where slots without reinforcement are provided:

ii)

æ
d
f
f ö
H = çç1 + 0.5
4.0 2 - 1.0 , without being taken less than 1 + 0.5
d
S
d
0
0 ø
1
è
where slots with reinforcement are provided:

d2

f
d0
: Depth of slots without reinforcement provided at the upper and lower parts of solid floors, in m,f
S2

whichever is greater: Major diameter of the openings, in m
: The smaller of S1 or a , in m.

H = 1 + 0.5－220－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

Table 5BDB
l DB

0.4 and

C2

0.48

under

Coefficient C 2
0.8

1.0

1.2

1.4

0.47

0.45

0.43

0.40

0.37

0.34

0.3 and

C 2¢

64

under

over

Coefficient C 2¢

Table 6
S1 / d 0

1.6 and

0.6

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

38

25

19

15

12

10

9

8

1.4 andover
7

2.4
Stringer of double side structure
2.4.1 Net web thickness
The net thickness of stringers in double side structure, in mm, is not to be less than the greatest of either of thevalue t1 to t3 specified in the followings according to each location:
pS x - x c, where x - x c is under 0.25l DS , x - x c is to be taken as 0.25l DS
t1 = C 3(d 0 - d 1 )t a
t 2 = 1.75 3t3 =H 2 a 2t a
t1
C 3¢

8 .5 S 2kwhere :p
: Differential pressure given by the following formula in kN/m2:
p = ( p S , SS + pW , SS ) - ( p S , LB + pW , LB )p S ,SS : External sea and ballast pressure of side shell plating in still water, in kN/m2, as measured verticallyat the upper end of hopper tank, longitudinally at the centre of l DS , according to Ch 4, Sec 5 and
Ch 4, Sec 6
pW , SS : External sea and ballast pressure of side shell plating due to inertia, in kN/m2, as measured verticallyat the upper end of hopper tank, longitudinally at the centre of l DS , according to Ch 4, Sec 5 and
Ch 4, Sec 6
p S , LB : Ballast pressure of longitudinal bulkhead in still water, in kN/m2, as measured vertically at the upper
end of hopper tank, longitudinally at the centre of l DS , according to Ch 4, Sec 6
pW , LB : Ballast pressure of longitudinal bulkhead due to inertia, in kN/m2, as measured vertically at theupper end of hopper tank, longitudinally at the centre of l DS , according to Ch 4, Sec 6
S
d0
d1
xc
l DS
h DS
C3

a

S1

:
:
:
:

Breadth of part supported by stringer, in m
Depth of stringers, in m
Depth of opening, if any, at the point under consideration, in m.
X co-ordinate, in m, of the center of double side structure under consideration with respect to thereference co-ordinate system defined in Ch 1, Sec 4: Length of the double side structure between the transverse bulkheads under consideration, in m
: Height of the double side structure between the upper end of hopper tank and the lower end of
topside tank, in m
: Coefficient obtained from Table 7 depending on h DS / l DS . For intermediate values of h DS / l DS ,C 3 is to be obtained by linear interpolation.
: Depth of stringers at the point under consideration, in m. However, where horizontal stiffeners are
fitted on the stringer, a is the distance from the horizontal stiffener under consideration to the side
shell plating or the longitudinal bulkhead of double side structure or the distance between thehorizontal stiffeners under consideration: Spacing, in m, of transverse ordinary stiffeners or web frames－221－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

C 3¢: Coefficient obtained from Table 8 depending on S1 / a . For intermediate values of S1 / a , C 3¢ isH

to be obtained by linear interpolation.
: Value obtained from the following formulae:
・ where the stringer is provided with an unreinforced opening:

f
a
S2

・
:
:
:

H = 1+ 0.5

fa

H = 1 .0
in other cases:
Major diameter of the openings, in m
The greater of a or S1 , in m
The smaller of a or S1 , in m

Table 7hDS
l DS

0.5 and

C3

0.16

under

S1
a

0.3 and

C 3'

64

under

Coefficient C 3

0.6

0.7

0.8

0.9

1.0

1.1

1.2

0.23

0.30

0.36

0.41

0.44

0.47

0.50

Table 8

Coefficient C 3¢

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

38

25

19

15

12

10

9

8

1.3 andover
0.54

1.4 andover
7

2.5
Transverse web in double side structure
2.5.1 Net web thickness
The net thickness of transverse webs in double side structure, in mm, is not to be less than the greatest of either ofthe value t1 to t3 specified in the followings according to each location:
pSh DS æz - z BH ö
ç1 - 1.75
t1 = C 4çh DS ø
(d 0 - d 1 )t a è
where z - z BH is greater than 0.4h DS , z - z BH is to be taken as 0.4h DS
t 2 = 1.75 3t3 =H 2 a 2t a
t1
C 4¢

8 .5 S 2kwhere :S
: Breadth of part supported by transverses, in m
d 0 : Depth of transverses, in m
d 1 : Depth of opening at the point under consideration, in m
C 4 : Coefficient obtained from Table 9 depending on h DS / l DS . For intermediate values of h DS / l DS ,C 4 is to be obtained by linear interpolationz BH : Z co-ordinates, in m, of the upper end of hopper tank with respect to the reference co-ordinate systemdefined in Ch 1, Sec 4
p , h DS and l DS : as defined in the requirements of 2.4.1
a

S1
C 4¢

: Depth of transverses at the point under consideration, in m. However, where vertical stiffeners are
fitted on the transverse, a is the distance from the vertical stiffener under consideration to the side
shell or the longitudinal bulkhead of double side hull or the distance between the vertical stiffeners
under consideration.
: Spacing, in m, of horizontal ordinary stiffeners or stringers: Coefficient obtained from Table 10 depending on S1 / a . For intermediate values of S1 / a , C 4¢ isH

to be obtained by linear interpolation.
: Value obtained from the following formulae :－222－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)・ where the transverse is provided with an unreinforced opening: H = 1+ 0.5

f
a

S2

f
a

H = 1 .0
・ in other cases:: Major diameter of the openings, in m
: The greater of a or S1 , in m
: The smaller of a or S1 , in m

Table 9hDS
l DS

0.5 and

C4

0.62

under

S1
a

C 4'

Coefficient C 4

0.6

0.7

0.8

0.9

1.0

1.1

1.2

0.61

0.59

0.55

0.52

0.49

0.46

0.43

0.3 and
under
64

Table 10

Coefficient C 4¢

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

38

25

19

15

12

10

9

8

1.3 andover
0.41

1.4 andover7

2.6
Primary supporting member in bilge hopper tanks and topside tanks and other structures
2.6.1 Load calculation point
For horizontal members, the lateral pressure and hull girder stress, if any, are to be calculated at mid-span of the
primary supporting members considered, unless otherwise specified.
For vertical members, the lateral pressure p is to be calculated as the maximum between the values obtained at
mid-span and the pressure obtained from the following formula:p + pL・ p= U, when the upper end of the vertical member is below the lowest zero pressure level2
l p
・ p = 1 L , when the upper end of the vertical member is at or above the lowest zero pressure level (see Fig. 1)
l 2
where:
l1: Distance, in m, between the lower end of vertical member and the lowest zero pressure level
pU , p L : Lateral pressures at the upper and lower end of the vertical member span l, respectively
Fig. 1

Definition of pressure for vertical members

2.6.2 Boundary conditions
The requirements of this sub-article apply to primary supporting members considered as clamped at both ends. For
boundary conditions deviated from the above, the yielding check is to be considered on a case by case basis.
2.6.3 Net section modulus, net shear sectional area and web thickness under intact conditions
The net section modulus w , in cm3, the net shear sectional area Ash , in cm2, and the net web thickness t w , in mm,
subjected to lateral pressure are to be not less than the values obtained from the following formulae:－223－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)w=( p S + pW )sl 2

Ash =m l S RY

10 3

5( p S + pW )sl
t a sin f

t w = 1.75 3

hwt a
10 4 C 5

Ashwhere:
lS : Coefficient defined in Table 11
f : Angle, in deg, between the primary supporting member web and the shell plate, measured at the
middle of the member span; the correction is to be applied when f is less than 75 deg.
C 5 : Coefficient defined in Table 12 according to s1 and d 0 . For intermediate values of s1 / d 0 ,coefficient C 5 is to be obtained by linear interpolation.
s1 : Spacing of stiffeners or tripping brackets on web plate, in m
d 0 : Spacing of stiffeners parallel to shell plate on web plate, in m
Coefficient lS

Table 11
Primary supporting members

Coefficient lS

Longitudinal members contributing to the hull girderæs ö
1.1ç1.0 - 0.85 X , without being taken greater than 0.8
ç
RY ø
è

longitudinal strength
Other members

0.8

Table 12
s1/d0
C5

3.

Coefficient C5

0.3 and less

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.5

2.0 and over

60.0

40.0

26.8

20.0

16.4

14.4

13.0

12.3

11.1

10.2

Additional requirements for primary supporting members of BC-A and BC-B ships

3.1
Evaluation of double bottom capacity and allowable hold loading in flooded conditions
3.1.1 Shear capacity of the double bottom
The shear capacity of the double bottom is to be calculated as the sum of the shear strength at each end of:・ all floors adjacent to both hopper tanks, less one half of the shear strength of the two floors adjacent to eachstool, or transverse bulkhead if no stool is fitted (see Fig. 2); the floor shear strength is to be calculated
according to 3.1.2,
・ all double bottom girders adjacent to both stools, or transverse bulkheads if no stool is fitted; the girder shear
strength is to be calculated according to 3.1.3.
Where in the end holds, girders or floors run out and are not directly attached to the boundary stool or hopper tankgirder, their strength is to be evaluated for the one end only.
The floors and girders to be considered in calculating the shear capacity of the double bottom are those inside thehold boundaries formed by the hopper tanks and stools (or transverse bulkheads if no stool is fitted). The hopper tankside girders and the floors directly below the connection of the stools (or transverse bulkheads if no stool is fitted) tothe inner bottom may not be included.
When the geometry and/or the structural arrangement of the double bottom is/are such as to make the above
assumptions inadequate, the shear capacity of the double bottom is to be calculated by means of direct calculations to
be carried out according to the requirements specified in Ch 7, as far as applicable.
3.1.2 Floor shear strength
The floor shear strength, in kN, is to be obtained from the following formulae:
・ in way of the floor panel adjacent to the hopper tank:－224－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

S f 1 = Aft A -310h1・ in way of the openings in the outermost bay (i.e. that bay which is closer to the hopper tank):t
S f 2 = A f ,h A 10 -3h2
where:
Af : Net sectional area, in mm2, of the floor panel adjacent to the hopper tankAf,h : Net sectional area, in mm2, of the floor panels in way of the openings in the outermost bay (i.e. that bay
which is closer to the hopper tank): Allowable shear stress, in N/mm2, equal to the lesser of:
A
0.6
R
R eH
t A = 0.645
and t A = eH
0.8
(s / t N )
3
tN
s

:
:
:
:

Floor web net thickness, in mm
Spacing, in m, of stiffening members of the panel considered
Coefficient to be taken equal to 1.1
1
Coefficient to be taken equal to 1.2. It may be reduced to 1.1 where appropriate reinforcements are2
fitted in way of the openings in the outermost bay, to be examined by the Society on a case-by-casebasis.
3.1.3 Girder shear strength
The girder shear strength, in kN, is to be obtained from the following formulae:
・ in way of the girder panel adjacent to the stool (or transverse bulkhead, if no stool is fitted):t
S g1 = Ag A 10 -3
h1
・ in way of the largest opening in the outermost bay (i.e. that bay which is closer to the stool, or transversebulk-head, if no stool is fitted):t
S g 2 = Ag ,h A 10 -3
h2: Net sectional area, in mm2, of the girder panel adjacent to the stool (or transverse bulkhead, if no stool
is fitted)
Ag,h : Net sectional area, in mm2, of the girder panel in way of the largest opening in the outermost bay (i.e.
that bay which is closer to the stool, or transverse bulkhead, if no stool is fitted): Allowable shear stress, in N/mm2, defined in 3.1.2, where tN is the girder web net thickness
A: Coefficient to be taken equal to 1.1
1: Coefficient to be taken equal to 1.15. It may be reduced to 1.1 where appropriate reinforcements are2
fitted in way of the largest opening in the outermost bay, to be examined by the Society on acase-by-case basis.
3.1.4 Allowable hold loading
The allowable hold loading is to be obtained, in t, from the following formula:1
W = r CVF
where:
F: Coefficient to be taken equal to:
F = 1.1
in general
F = 1.05
for steel mill products
V: Volume, in m3, occupied by cargo at a level hB
hB : Level of cargo, in m2, to be obtained from the following formula:
X
hB =
rC g
Ag

X

: Pressure, in kN/m2, to be obtained from the following formulae:
・ for dry bulk cargoes, the lesser of:－225－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

X =Z + rg (z F - 0.1D1 - hF )1+r
( perm - 1)
rC

X = Z + rg ( z F - 0.1D1 - h F perm )・ for steel mill products:
Z + rg (z F - 0.1D1 - hF )
X =
r
1rC
D1
hF

: Distance, in m, from the base line to the freeboard deck at side amidships: Inner bottom flooding head is the distance, in m, measured vertically with the ship in the uprightposition, from the inner bottom to a level located at a distance zF, in m, from the baseline.
: Flooding level, in m, defined in Ch 4, Sec 6, 3.4.3
zF
perm : Permeability of cargo, which need not be taken greater than 0.3
Z: Pressure, in kN/m2, to be taken as the lesser of:CHZ=
ADB , H
Z=

CH

CE

CE
ADB , E: Shear capacity of the double bottom, in kN, to be calculated according to 3.1.1, considering, for eachfloor, the lesser of the shear strengths Sf1 and Sf2 (see 3.1.2) and, for each girder, the lesser of theshear strengths Sg1 and Sg2 (see 3.1.3): Shear capacity of the double bottom, in kN, to be calculated according to 3.1.1, considering, for eachfloor, the shear strength Sf1 (see 3.1.2) and, for each girder, the lesser of the shear strengths Sg1 and Sg2(see 3.1.3)
n・ADB, H = å S i B DB,i
i =1
n

・

ADB, E = å S i (B DB - s )i =1n: Number of floors between stools (or transverse bulkheads, if no stool is fitted)
Si: Space of i-th floor, in m
BDB,i : Length, in m, to be taken equal to :BDB,i = BDB s for floors for which Sf1 < Sf2 (see 3.1.2)
BDB,i = BDB,hfor floors for which Sf1 Sf2 (see 3.1.2)
BDB : Breadth, in m, of double bottom between the hopper tanks (see Fig. 3)
BDB,h : Distance, in m, between the two openings considered (see Fig. 3)s: Spacing, in m, of inner bottom longitudinal ordinary stiffeners adjacent to the hopper tanks.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

4.

Fig. 2

Double bottom structure

Fig. 3

Dimensions BDB and BDB,hPillars

4.1
Buckling of pillars subjected to compressive axial load
4.1.1 General
It is to be checked that the compressive stress of pillars does not exceed the critical column buckling stresscalculated according to 4.1.2.
4.1.2 Critical column buckling stress of pillars
The critical column buckling stress of pillars is to be obtained, in N/mm2, from the following formulae:Rs cB = s E1for s E1 £ eH
2
æR eH ö
R eH
for s E1 >s cB = ReH çç1 2
è 4s E1 ø
where:
sE1 : Euler column buckling stress, to be obtained, in N/mm2, from the following formula:I
s E1 = p 2 E
10 - 4
2
A( fl )I
A
f

: Minimum net moment of inertia, in cm4, of the pillar: Net cross-sectional area, in cm2, of the pillar: Coefficient to be obtained from Table 13.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Section 4)

Table 13

Coefficient f

Boundary conditions of the pillarfBoth ends fixed

0.5

One end fixed, one end pinned22Both ends pinned

1.0

5.

Flooding check of primary supporting members

5.1
Net section modulus and net shear sectional area under flooded conditions
5.1.1
The net section modulus w , in cm3, the net shear sectional area Ash, in cm2 subjected to flooding are to be not lessthan the values obtained from the following formulae:
pF sl 2w=
103
16alS RYAsh =5 p F sl
at a sin f

Where :
a : Coefficient taken equal to:a = 0.95
for the primary supporting member of collision bulkhead
a = 1.15
for the primary supporting member of other watertight boundaries of compartmentslS : Coefficient defined in Ch 6, Sec 4 Table 11, determined by considering s X in flooded condition.
pF : Pressure, in kN/m2, in flooded conditions, defined in Ch 4, Sec 6, 3.2.1.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Appendix 1)

Appendix 11.

BUCKLING & ULTIMATE STRENGTH

Application of Ch 6, Sec 3

1.1
General application
1.1.1 Mutable shear stress
If shear stresses are not uniform on the width b of the elementary plate panel, the greater of the two following
values is to be used:・ mean value of・ 0.5 max
1.1.2 Change of thickness within an elementary plate panel
If the plate thickness of an elementary plate panel varies over the width b, the buckling check may be performed
for an equivalent elementary plate panel a b' having a thickness equal to the smaller plate thickness t1.
The width of this equivalent elementary plate panel is defined by the following formula:
1.5

æt ö
b ' = b1 + b2 çç 1
è t2 ø
where:
b1 : Width of the part of the elementary plate panel with the smaller plate thickness t1
b2 : Width of the part of the elementary plate panel with the greater plate thickness t2

Fig. 1b1

Plate thickness change within the field breath
b2

t1

t2
b

1.1.3 Evaluation of floors or other high girders with holes
The following procedure may be used to assess high girders with holes:a) Divide the plate field in sub elementary plate panels according the Fig. 2b) Assess the elementary plate panel and all sub elementary plate panels separately with the following boundary
conditions:・ for sub panels 1 to 4: all edges are simply supported (load cases 1 and 2 in Ch 6, Sec 3, Table 2)・ for sub panels 5 and 6: simply supported, one side free (load case 3 in Ch 6, Sec 3, Table 2).

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Appendix 1)

Fig. 2Elementary plate panels of high girder with hole

3

1

1

r
5

6
4

2
2

r/3

1.2
Application to hull transverse section analysis
1.2.1 Idealization of elementary plate panels
The buckling check of the elementary plate panel is to be performed under the loads defined in Ch 6, Sec 3, 2.1,
according to the requirements of Ch 6, Sec 3, 3.
The determination of the buckling and reduction factors is made according to the Ch 6, Sec 3, Table 2 for theplane plate panel and Ch 6, Sec 3, Table 3 for the curved plate panel.
For the determination of the buckling and reduction factors in Ch 6, Sec 3, Table 2, the following cases are to be
used according to the type of stresses and framing system of the plating:・ For the normal compressive stress:
・ Buckling load case 1 for longitudinally framed plating, the membrane stress in x-direction s x being the normal
stress sn defined in Ch 6, Sec 3, 2.1.2
・ Buckling load case 2 for transversely framed plating, the membrane stress in y-direction s y being the normal
stress sn defined in Ch 6, Sec3, 2.1.2, and the values a and b being exchanged to obtain a value greater than 1
as it is considered in load case 2.
・ For the shear stress: Buckling case 5, t being the shear stress tSF defined in Ch 6, Sec 3, 2.1.3.
Fig. 3

Idealization of elementary plate panels
s1u
sx global

s1u

1

Load
case

2

Load
case

s1l = y × s1u

s1l

s2u

s2u
s2l

s2l = y × s2u

sy localsx global

1.2.2 Ordinary stiffeners
The buckling check of the longitudinal and transverse ordinary stiffeners of partial and total plate panels (see Ch 6,
Sec 3, Fig. 1) is to be performed under the loads defined in Ch 6, Sec 3, 2.1, according to Ch 6, Sec 3, 4 with:・ s x = normal stress sn defined in Ch 6, Sec 3, 2.1.2
・ sy =0－230－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Appendix 1)

The effective width of the attached plating of the stiffeners is to be determined in accordance with Ch 6, Sec 3, 5.
A constant stress is to be assumed corresponding to the greater of the following values:
・ stress at half length of the stiffener・ 0.5 of the maximum compressive stress of adjacent elementary plate panels
1.2.3 Primary supporting members with stiffeners in parallel
The effective width of the attached plating of the primary supporting members is to be determined in accordancewith Ch 6, Sec 3, 5.2.
In addition, when ordinary stiffeners are fitted on the attached plate and parallel to a primary supporting member,the buckling check is to consider a moment of inertia Ix taking account the moments of inertia of the parallel ordinary
stiffeners connected to its attached plate (see Ch 6, Sec 3, Fig. 3).
1.2.4 Primary supporting members with stiffener perpendicular to girder
The effective width of the attached plating of the primary supporting members is to be determined in accordancewith Ch 6, Sec 3, 5.2.
In addition, when ordinary stiffeners are fitted on the attached plate and perpendicular to a primary supporting
member, the buckling check is to consider a moment of inertia Ix taking account the effective width according to (seeCh 6, Sec 3, Fig. 4).
1.3
Additional application to FEM analysis
1.3.1 Non uniform compressive stresses along the length of the buckling panel
If compressive stresses are not uniform over the length of the unloaded plate edge (e.g. in case of girders subjected
to bending), the compressive stress value is to be taken at a distance of b/2 from the transverse plate edge having thelargest compressive stress (see Fig. 4). This value is not to be less than the average value of the compressive stressalong the longitudinal edge.
Fig. 4

Non uniform compressive stress along longitudinal edge a

b

sx
b/2

1.3.2 Buckling stress calculation of non rectangular elementary plate panelsa) Quadrilateral panels
According to Fig. 5, rectangles that completely surround the irregular buckling panel are searched. Among
several possibilities the rectangle with the smallest area is taken. This rectangle is shrunk to the area of theoriginal panel, where the aspect ratio and the centre are maintained. This leads to the final rectangular panel withthe dimensions a, b.

－231－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Appendix 1)

Fig. 5

Approximation of non rectangular elementary plate panelsbaOriginal irregular panel ()
Intermediate rectangles ()
Rectangle with smallest area (Final rectangle ()b))

Trapezoidal elementary plate panel
A rectangle is derived with a being the mean value of the bases and b being the height of the original panel.
Fig. 6

Approximation of trapezoidal elementary plate panel

b

a

c)

Right triangle
The legs of the right triangle are reduced by
Fig. 7

0.5 to obtain a rectangle of same area and aspect ratio.

Approximation of right triangle

b
a

d)

General triangle
General triangle is treated according to a) above.
1.3.3 Buckling assessment of side shell plates
In order to assess the buckling criteria for vertically stiffened side shell plating, the following cases have to beconsidered:
In case vertical and shear stresses are approximately constant over the height of the elementary plate panel:－232－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Appendix 1)

・ Buckling load cases 1, 2 and 5, according to Ch 6, Sec 3, Table 2 are to be considered・ y = f (s , s ) for horizontal stresses
1 2・ y = 1.0 for vertical stresses
・ t = tmin (Elementary plate panel)
In case of distributed horizontal, vertical and shear stresses over the height of the elementary plate panel, thefollowing stress situations are to be considered separately:a) Pure vertical stress・ The size of buckling field to be considered is b times b ( a = 1 )・ y = 1.0b)c)・ The maximum vertical stress in the elementary plate panel is to be considered in applying the criteria
Shear stress associated to vertical stress・ The size of buckling field to be considered is 2b times b ( a = 2 )・ y = 1.0
・ The following two stress combinations are to be considered:・ The maximum vertical stress in the elementary plate panel plus the shear stress and longitudinal stressat the location where maximum vertical stress occurs
・ The maximum shear stress in the elementary plate panel plus the vertical stress and longitudinal stressat the location where maximum shear stress occurs
・ The plate thickness t to be considered is the one at the location where the maximum vertical/shear stressoccursDistributed longitudinal stress associated with vertical and shear stress・ The actual size of the elementary plate panel is to be used ( a = f (a, b) ).

・ The actual edge factor for longitudinal stress is to be used
・ The average values for vertical stress and shear stress are to be used.
・ t = tmin (Elementary plate panel)
1.3.4 Buckling assessment of corrugated bulkheads
The transverse elementary plate panel (face plate) is to be assesed using the normal stress parallel to thecorrugation. The slanted elementary plate panel (web plate) is to be assessed using the combination of normal andshear stresses.
The plate panel breadth b is to be measured according to Fig. 8.
Fig. 8

Measuring b of corrugated bulkheads
Face plate

Web plate

b

a)

b)

Face plate assessment
・ The buckling load case 1, according to Ch 6, Sec 3, Table 2, is to be used
・ The size of the buckling field to be considered is b times b ( a = 1 )・ y = 1.0
・ The maximum vertical stress in the elementary plate panel is to be considered in applying the criteria
・ The plate thickness t to be considered is the one at the location where the maximum vertical stress occurs
Web plate assessment
・ The buckling load cases 1 and 5, according to Ch 6, Sec 3, Table 2, are to be used.
・ The size of the buckling field to be considered is 2b times b ( a = 2 )・ y = 1.0－233－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 6 Appendix 1)

・ The following two stress combinations are to be considered:・ The maximum vertical stress in the elementary plate panel plus the shear stress and longitudinal stressat the location where maximum vertical stress occurs
・ The maximum shear stress in the elementary plate panel plus the vertical stress and longitudinal stressat the location where maximum shear stress occurs
・ The plate thickness t to be considered is the one at the location where the maximum vertical/shear stressoccurs.

－234－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 1)

Chapter 7
Section 1

1.

DIRECT STRENGTH ANALYSISDIRECT STRENGTH ASSESSMENT OF THE PRIMARYSUPPORTING MEMBERS

General1.1
Application
1.1.1
Direct strength assessment of primary supporting members based on a three-dimensional (3D) finite element (FE)analysis is to be applied to ships having length L of 150 m or above.
1.1.2
Three kinds of FE analysis procedures are specified in this Chapter:a) global strength FE analysis (first FE analysis step) to assess global strength of primary supporting members of
the cargo hold structure, according to Sec 2.
b) detailed stress assessment (second FE analysis step) to assess highly stressed areas with refined meshes,according to Sec 3c) hot spot stress analysis (third FE analysis step) to calculate hot spot stresses at stress concentration points withvery fine meshes for fatigue strength assessment, according to Sec 4.
A flowchart of FE analysis procedure for direct strength assessment is shown in Fig. 1.
1.2
Computer program
1.2.1
Computer programs for FE analysis are to be suitable for the intended analysis. Reliability of unrecognizedprograms is to be demonstrated to the satisfaction of the Society prior to the commencement of the analysis.
1.3
Submission of analysis report
1.3.1
A detailed report of direct strength FE analysis is to be submitted, including background information of theanalysis. This report is to include the following items:a) list of drawings/plans used in the analysis, including their versions and datesb) detailed description of structural modeling principles and any deviations in the model from the actual structuresc) plots of structural modeld) material properties, plate thickness and beam properties used in the modele) details of boundary conditionsf) all loading conditions analyzedg) data for loads applicationh) summaries and plots of calculated deflectionsi) summaries and plots of calculated stressesj) details of buckling strength assessmentk) tabulated results showing compliance with the design criterial) reference of the finite element computer program, including its version and date.
1.4
Net scantling
1.4.1
Direct strength analysis is to be based on the net scantling approach according to Ch 3, Sec 2.
1.5
Applied loads
1.5.1 Design loads
Direct strength analysis is to be carried out by applying design loads given in Ch 4 at a probability level of 10-8,
except for fatigue strength assessment where probability level is 10-4. Combination of static and dynamic loads which
are likely to impose the most severe load regime are to be applied to the 3D FE model.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 1)

1.5.2 Structural weight
Effect of the hull structure weight is to be included in static loads, but is not to be included in dynamic loads.
Standard density of steel is to be taken as 7.85 t/m3.
1.5.3 Loading conditions
The loading conditions specified in Ch 4, Sec 7 are to be considered in 3D FE analysis.
Fig. 1

Flowchart of FE analysis procedure
Bulk Carrier

150 m

Direct Strength Assessment

Loading conditions(Ch 4, Sec 7)

Boundary Conditions

Global FE analysis of

Design Loads (Ch 4)

cargo hold structures
Corrosion additions (Ch 3,Sec 3)

Hull Girder loads

Yielding Assessment

Fatigue Assessment(Sec 4 & Ch 8)

Buckling Assessment

Refined mesh FE analysis
of highly stressed areas

Very fine mesh FE analysis
of fatigue sensitive areas－236－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)

Section 2

GLOBAL STRENGTH FE ANALYSIS OF CARGO HOLD
STRUCTURES

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Design vertical bending moment as defined in Ch 4, Sec 7, Table 2.
MSW: Vertical wave bending moment, in hogging or sagging condition, as defined in Ch 4, Sec 3, 3.1.1
MWV
MWH: Horizontal wave bending moment, as defined in Ch 4, Sec 3, 3.3.1: Allowable still water shear force at the considered bulkhead position as provided in Ch 4, Sec 7, Table 3
QSW: Vertical wave shear force as defined in Ch 4, Sec 3, 3.2.1
QWV
CWV, CWH : Load combination factors, as defined in Ch 4, Sec 4, Table 3.

1.

General1.1
Application
1.1.1
The procedure given in this Section focuses on direct strength analysis of cargo hold structures in midship area.
1.1.2
The global strength FE analysis of cargo hold structures is intended to verify that the following are within theacceptance criteria under the applied static and dynamic loads:a) stress level in the hull girder and primary supporting membersb) buckling capability of primary supporting membersc) deflection of primary supporting members.
2.

Analysis model

2.1
Extent of model
2.1.1
The longitudinal extent of FE model is to cover three cargo holds and four transverse bulkheads. The transverse
bulkheads at the ends of the model extent are to be included, together with their associated stools. Both ends of themodel are to form vertical planes and to include any transverse web frames on the planes if any. The details of theextent of the model are given in App 1.
2.1.2
FE model is to include both sides of ship structures considering unsymmetrical wave-induced loads in thetransverse direction.
2.1.3
All main structural members are to be represented in FE model. These include inner and outer shell, floor andgirder system in double bottom, transverse and vertical web frames, stringers, transverse and longitudinal bulkhead
structures. All plates and stiffeners on these structural members are to be modelled.
2.2
Finite element modeling
2.2.1
All main structural members (plates and stiffeners) detailed in 2.1.3 are to be represented in FE model.
2.2.2
Mesh boundaries of finite elements are to simulate the stiffening systems on the actual structures as far as practicaland are to represent the correct geometry of the panels between stiffeners.

－237－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)

2.2.3
Stiffness of each structural member is to be represented correctly by using proper element type for the structuralmember. The principle for selection of element type is given below.
(1) Stiffeners are to be modeled by beam or bar element having axial, torsional, bi-directional shear and bending
stiffness. However, web stiffeners and face plates of primary supporting members may be modeled by rod
element having only axial stiffness and a constant cross-sectional area along its length.
(2) Plates are to be modeled by shell element having out-of-plane bending stiffness in addition to bi-axial andin-plane stiffness. However, membrane element having only bi-axial and in-plane stiffness can be used for plates
that are not subject to lateral pressures.
For membrane and shell elements, only linear quad or triangle elements, as shown in Fig. 1, are to be adopted.
Fig. 1

Linear membrane and shell quad and triangle elements

Triangle elements are to be avoided as far as possible, especially in highly stressed areas and in such areas
around openings, at bracket connections and at hopper connections where significant stress gradient should be
predicted.
(3) Stiffened panels may be modeled by two-dimensional (2D) orthotropic elements that can represent the stiffnessof the panels properly.
2.2.4
When orthotropic elements are not used in FE model:
・ mesh size is to be equal to or less than the representative spacing of longitudinal stiffeners or transverse side
frames・ stiffeners are to be modeled by using rod and/or beam/bar elements
・ webs of primary supporting members are to be divided at least three elements height-wise
However, for transverse primary supporting members inside hopper tank and top side tank, which are less inheight than the space between ordinary longitudinal stiffeners, two elements on the height of primary supporting
members are accepted.
・ side shell frames and their end brackets are to be modeled by using shell elements for web and shell/beam/rod
elements for face plate. Webs of side shell frames need not be divided along the direction of depth
・ aspect ratio of elements is not to exceed 1:4.
An example of typical mesh is given in App 1.
2.2.5
When orthotropic elements are used in FE model for stiffened panels:
・ for the members such as the double bottom girder or floor, the element height is to be the double bottom height.
・ where a stiffener is located along the edge between two orthotropic elements, either it is to be modelled by using
beam/rod element, or it is virtually modelled by reporting the stiffness of the stiffener onto the two orthotropic
elements
・ where a stiffener is located along the edge between an orthotropic element and a membrane/shell element, it is tobe modelled by using beam/rod element
・ where a stiffener is located along the edge between two membrane/shell elements, it is to be modelled by using
beam/rod element
・ where a double hull is fitted, the web of the primary supporting members is to be modelled with one element on
its height・ where no double hull construction is fitted, at least one over three frame and its associated end brackets are to bemodelled by using shell elements for the webs and shell/beam elements for the flanges
・ the aspect ratio of the elements is not to exceed 1:2.
－238－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)

2.3
Boundary conditions
2.3.1
Both ends of the model are to be simply supported according to Table 1 and Table 2. The nodes on thelongitudinal members at both end sections are to be rigidly linked to independent points at the neutral axis on thecentreline as shown in Table 1. The independent points of both ends are to be fixed as shown in Table 2.
Table 1

Rigid-link of both ends

Nodes on longitudinal members

Translational

at both ends of the model
All longitudinal members

Rotational

Dx

Dy

Dz

Rx

Ry

Rz

RL

RL

RL

-

-

-

RL means rigidly linked to the relevant degrees of freedom of the independent point

Table 2

Support condition of the independent point
Translational

Location of the independent point

Rotational

Dx

Dy

Dz

Rx

Ry

Rz

Independent point on aft end of model

-

Fix

Fix

Fix

-

-

Independent point on fore end of model

Fix

Fix

Fix

Fix

-

-

2.4
Loading conditions
2.4.1 General
The loading conditions, combined with loading patterns and load cases, as illustrated in Ch 4, App 2, are to beconsidered as mandatory conditions for the conventional designs.
2.5
Consideration of hull girder loads
2.5.1 General
Each loading condition is to be associated with its corresponding hull girder loads. The load combination is to beconsidered using Load Combination Factors (LCFs) of the wave-induced vertical and horizontal bending moments
and of the wave-induced vertical shear forces specified in Ch 4, Sec 4 for each Load Case.
2.5.2 Vertical bending moment analysis
Vertical bending moment analysis is to be performed for cases listed in Ch 4, Sec 7, Table 2, the minimum
required cases being listed in Ch 4, App 2.
In vertical bending moment analysis the target hull girder loads are the maximum vertical bending moments which
may occur at the centre of the mid-hold in the FE model. The target values of hull girder loads are to be obtained inaccordance with Table 3 with considering still water vertical bending moments specified in Ch 4, Sec 7, Table 2,
and in Ch 4, App 2.
Table 3

Target loads for vertical bending moment analysis

Hull girder effect

Still water

Wave

Considered Location

Vertical bending moment

MSW

CWV MWV

Centre of mid-hold

Vertical shear force

00Centre of mid-holdHorizontal bending moment---

CWH MWH

Centre of mid-holdHorizontal shear force---

0

Centre of mid-hold

2.5.3 Vertical shear force analysis
Vertical shear force analysis is to be performed for cases listed in Ch 4, Sec 7, Table 3, the minimum required
cases being listed in Ch 4, App 2.
In vertical shear force analysis the target hull girder loads are the maximum vertical shear force which may occur
at one of the transverse bulkheads of the mid-hold in the FE model. Reduced vertical bending moments are－239－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)

considered simultaneously. The target values of hull girder loads are to be obtained in accordance with Table 4 withconsidering still water vertical bending moments and shear forces specified in Ch 4, Sec 7, Table 2 and Ch 4, Sec 7,
Table 3, and in Ch 4, App 2.
Table 4

Target loads for vertical shear force analysis

Hull girder effect

Still water

Wave

Location

Vertical bending moment

0.8MSW

0.65 CWV MWV

Transverse bulkhead

Vertical shear force

QSW

QWV

Transverse bulkhead

Horizontal bending moment---

0

Transverse bulkhead

Horizontal shear force---

0

Transverse bulkhead

2.5.4 Influence of local loads
The distribution of hull girder shear force and bending moment induced by local loads applied on the model arecalculated using a simple beam theory for the hull girder.
Reaction forces at both ends of the model and distributions of shearing forces and bending moments induced by
local loads can be determined by following formulae:r råi ( xi - x aft ) f i zr r
RV _ fore = RV _ aft = å f i z + RV _ fore
x fore - x aftir rå ( xi - x aft ) f i yr r
R H _ fore = i
R H _ aft = -å f i y + R H _ fore
x fore - x aftir r
when xi < x
QV _ FEM ( x) = RV _ aft - å f i z
ir rwhen xi < x
Q H _ FEM ( x) = R H _ aft + å f i yir rwhen xi < x
M V _ FEM ( x) = ( x - x aft ) RV _ aft - å ( x - x i ) f i z
ir rwhen xi < x
M H _ FEM ( x) = ( x - x aft ) R H _ aft + å ( x - x i ) f i yiwhere:
x aft : Location of the aft end support,
x fore : Location of the fore end support,x: Considered location,
RV _ aft , RV _ fore , R H _ aft and R H _ fore

: Vertical and horizontal reaction forces at the fore and aft

ends
QV _ FEM , Q H _ FEM , M V _ FEM and M H _ FEM : Vertical and horizontal shear forces and bending moments
created by the local loads applied on the FE model. Sign of
QV _ FEM , M V _ FEM and M H _ FEM is in accordance with the

r
fi

xi

sign convention defined in Ch 4, Sec 3. The sign convention
for reaction forces is that a positive creates a positive shear
force.
: Applied force on node i due to all local loads,: Longitudinal coordinate of node i.

2.5.5 Methods to account for hull girder loads
For bending moment analysis, two alternative methods can be used to consider the hull girder loads/stresses in theassessment of the primary supporting members:a) to add the hull girder loads directly to FE model (direct method), or－240－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)b)

to superimpose the hull girder stresses separately onto the stresses obtained from the structural analysis using thelateral loads (superimposition method).
For shear force analysis, the direct method is to be used.
2.5.6 Direct method
In direct method the effect of hull girder loads are directly considered in 3D FE model. The equilibrium loads areto be applied at both model ends in order to consider the hull girder loads as specified in 2.5.2 and 2.5.3 and influenceof local loads as specified in 2.5.4.
In order to control the shear force at the target locations, two sets of enforced moments are applied at both ends ofthe model. These moments are calculated by following formulae:( x fore - x aft )M Y _ aft _ SF = M Y _ fore _ SF =QV _ T ( x eq ) - QV _ FEM ( x eq )2
( x fore - x aft )M Z _ aft _ SF = M Z _ fore _ SF =Q H _ T ( x eq ) - Q H _ FEM ( x eq )2In order to control the bending moments at the target locations, another two sets of enforced moments are appliedat both ends of the model. These moments are calculated by following formulae:éæ x eq - x aftöù-1 ú
M Y _ aft _ BM = - M Y _ fore _ BM = - êM V _ T ( x eq ) - M V _ FEM ( x eq ) - M Y _ aft _ SF ç 2
ç x fore - x aft
è
øûú
ëê
é
æ x eq - x aftöù-1 ú
M Z _ aft _ BM = - M Z _ fore _ BM = - ê M H _ T ( x eq ) - M H _ FEM ( x eq ) - M Z _ aft _ SF ç 2
ç x fore - x aftêëèøúû
where:
x eq : Considered location for the hull girder loads evaluation,

[

]

[

]

QV _ FEM , Q H _ FEM , M V _ FEM , M H _ FEM : Asdefined in 2.5.4
QV _ T , Q H _ T , M V _ T , M H _ T : Target vertical and horizontal shear forces and bending moments, definedin Table 3 or Table 4, at the location x eq . Sign of QV _ T , M V _ T and
M H _ T is in accordance with sign convention defined in Ch 4, Sec 3.
M Y _ aft _ SF , M Y _ fore _ SF , M Y _ aft _ BM , M Y _ fore _ BM : Enforced moments to apply at the aft and fore ends forvertical shear force and bending moment control,
positive for clockwise around y-axis. The sign
convention for M Y _ aft _ SF , M Y _ fore _ SF , M Y _ aft _ BM
and M Y _ fore _ BM is that of the FE model axis. The
sign convention for other bending moment, shear
forces and reaction forces is in accordance with thesign convention defined in Ch 4, Sec 3.
M Z _ aft _ SF , M Z _ fore _ SF , M Z _ aft _ BM , M Z _ fore _ BM : Enforced moments to apply at the aft and fore ends forhorizontal shear force and bending moment control,
positive for clockwise around z-axis. The sign
convention for M Z _ aft _ SF , M Z _ fore _ SF , M Z _ aft _ BM
and M Z _ fore _ BM is that of the FE model axis. The
sign convention for other bending moment, shear
forces and reaction forces is in accordance with thesign convention defined in Ch 4, Sec 3.
The enforced moments at the model ends can be generated by one of the following methods:
・ to apply distributed forces at the end section of the model, with a resulting force equal to zero and a resulting
moment equal to the enforced moment. The distributed forces are applied to the nodes on the longitudinal
members where boundary conditions are given according to Table 1. The distributed forces are to be determinedby using the thin wall beam theory
・ to apply concentrated moments at the independent points defined in 2.3.1.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)

2.5.7 Superimposition method
For vertical bending moment analysis in the superimposition method, the stress obtained from the following
formula is to be superimposed to the longitudinal stress of each element in longitudinal members obtained from 3D
FE analysis. Vertical shear force analyses are to be in accordance with 2.5.6.
MV _T
M H _Ts SIM =I Y / (z - N ) I Z / y
where
MV_T , MH_T : Target vertical and horizontal bending moments at considering section, respectively, withcorrections due to local loads, taken equal to:M V _ T = M SW + CWV M WV - M V _ FEM
M H _ T = CWH M WH - M H _ FEM

IY :
IZ :
N :
y :
z :
3.

Vertical inertia of the section around horizontal neutral axis, calculated according to Ch 3, Sec 2, 3.2.1
Horizontal inertia of the section, calculated according to Ch 3, Sec 2, 3.2.1
Z co-ordinate of the centre of gravity of the hull transverse section, as defined in Ch 5, Sec 1
Y co-ordinate of the element
Z co-ordinate of the element.

Analysis criteria

3.1
General3.1.1 Assessment holds
All the primary supporting members in the mid-hold of the three-hold (1+1+1) FE model, including bulkheads, areto be evaluated in 3D FE analysis.
3.1.2
The results of the structural analysis are to satisfy the criteria for yielding strength, buckling strength and deflectionof primary members.
3.2
Yielding strength assessment
3.2.1 Reference stresses
Reference stress is Von Mises equivalent stress at the centre of a plane element (shell or membrane) or axial stressof a line element (bar, beam or rod) obtained by FE analysis through considering hull girder loads according to 2.5.4
or 2.5.5.
Where the effects of openings are not considered in the FE model, the reference stresses in way of the openings areto be properly modified with adjusting shear stresses in proportion to the ratio of web height and opening height.
Where elements under assessment are smaller than the standard mesh size specified in 2.2.4 or 2.2.5, the reference
stress may be obtained from the averaged stress over the elements within the standard mesh size.
3.2.2 Equivalent stress
Von Mises equivalent stress is given by the following formula:seq = s x2 - s xs y + s y 2 + 3t xy2

sx, sy : Element normal stresses, in N/mm2
txy: Element shear stress, in N/mm2
In superimposition method, the stress sSIM, defined in 2.5.7, is to be superimposed onto to longitudinal stresscomponent.
3.2.3 Allowable stress
The reference stresses in FE model that does not include orthotropic elements, as specified in 2.2.4, are not toexceed 235/k N/mm2, where k is the material factor defined in Ch 3, Sec 1.
The reference stresses in FE model that includes orthotropic elements, as specified in 2.2.5, are not to exceed 205/k
N/mm2, where k is the material factor defined in Ch 3, Sec 1.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)

3.3
Buckling and ultimate strength assessment
3.3.1 General
Buckling and ultimate strength assessment is to be performed for the panels on primary supporting members
according to Ch 6, Sec 3.
3.3.2 Stresses of panel
The stresses in each panel are to be obtained according to the following procedures:
1) when the mesh model differs from the elementary plate panel geometry, the stresses sx ,sy and t acting on anelementary plate panel are to be evaluated by extrapolation and/or interpolation of surrounding meshes using theelements stresses or using the displacement based method described in App 2.
2) stresses obtained from with superimposed or direct method have to be reduced for buckling assessment becauseof the Poisson effect, which is taken into consideration in both analysis methods. The correction has to be
carried out after summation of stresses due to local and global loads.
When the stresses s *x and s *y are both compressive stresses, a stress reduction is to be made according to thefollowing formulae:s x = (s x* - 0.3s *y ) / 0.91

s y = (s *y - 0.3s x* ) / 0.91
Where compressive stress fulfils the condition s *y < 0.3s x* , then s y = 0 and s x = s *x
Where compressive stress fulfils the condition s x* < 0.3s *y , then s x = 0 and s y = s *y

s x* , s *y : Stresses containing the Poisson effect3)
4)

determine stress distributions along edges of the considered buckling panel by introducing proper linear
approximation as shown in Fig. 2.
calculate edge factor y according to Ch 6, Sec 3.
Fig. 2Stresses of panel for buckling assessment

sy*

yysy*

sx*

sx*
t
t

t
t

yxsx*
sy*

yxsx*
yysy*

3.3.3 Boundary conditions
Buckling load cases 1, 2, 5 or 6 of Ch 6, Sec 3, Table 2 are to be applied to the buckling panel under evaluation,
depending on the stress distribution and geometry of openings.
If the actual boundary conditions are significantly different from simple support condition, another case in Ch 6,
Sec 3, Table 2 can be applied.
3.3.4 Safety factor
The safety factor for the buckling and ultimate strength assessment of the plate is to be taken equal to 1.0.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 2)

3.4
Deflection of primary supporting members
The relative deflection, d max in mm, in the outer bottom plate obtained by FEA is not to exceed the following
criteria:

d max £

li
150

where:
d max : Maximum relative deflection, in mm, obtained by the following formula, and not including secondary
deflection
d max = max( d B1 , d B 2 )liwhere, d B1 and d B 2 are shown in Fig. 3.
: Length or breadth of the flat part of the double bottom, in mm, whichever is the shorter.
Fig. 3

Definition of relative deflection

li

dB1
dB2

li

dB1

dB2

－244－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 3)

Section 3
1.

DETAILED STRESS ASSESSMENT

General1.1
Application
1.1.1
This Section describes the procedure for the detailed stress assessment with refined meshes to evaluate highly
stressed areas of primary supporting members.
Where the global cargo hold analysis of Sec 2 is carried out using a model complying with the modelling criteria of
Sec 2, 2.2.4, the areas listed in Tab 1 are to be refined at the locations whose calculated stresses exceed 95% for
non-orthotropic elements or 85 % for orthotropic element but do not exceed 100% of the allowable stress as specified
in Sec 2, 3.2.3.
2.

Analysis model

2.1
Areas to be refined
2.1.1
Where the global cargo hold analysis of Sec 2 is carried out using a model complying with the modeling criteria of
Sec 2, 2.2.4, the areas listed in Table 1 are to be refined at the locations whose calculated stresses exceed 95% of theallowable stress as specified in Sec 2, 3.2.3.
2.1.2
Where the global cargo hold analysis of Sec 2 is carried out using a model complying with the modeling criteria of
Sec 2, 2.2.5, all the high stressed areas listed below are to be refined:
・ areas whose calculated stresses exceed 85% of the allowable stress as specified in Sec 2, 3.2.3.
・ typical details of the primary supporting members as shown in Table 1.
・ typical details of the transverse bulkheads of the considered hold as shown in Table 1.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 3)

Table 1
StructuralmemberArea of interest

Typical details to be refined
Additional specifications

Refining of the most stressed
Most stressedtransverse primary
supporting member
for double side skinconstruction

transverse primary
supporting members locatedin:double bottom
hopper tankdouble skin side
topside tankPrimary
supporting
memberRefining of the most stressedtransverse primary
Most stressedtransverse primary
supporting member
for single side skinconstrution

supporting members locatedin:double bottom
hopper tanktopside tankside shell frame with end
brackets and connections tohopper tank and topside tank

Most stressedHigh stressed elements,

connection of the

including the diaphragm(s)corrugations with theof the lower stool, are to belower stool

modelled

Transverse
bulkhead and its
associated lower
stool
Most stressed
connection of theHigh stressed elements are tolower stool with the

be modelled

inner bottom－246－

Description

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 3)

StructuralmemberArea of interest

Inner bottom andAdditional specifications

Refining of the most stressed

hopper sloping

Most stressedfollowing members:

plates with theirconnection of theinner bottom

associatedinner bottom with the hopper sloping plate

supporting

hopper sloping plate

membersfloor
girderDeck plating in way
Deck plating

Descriptionof the most stressed
hatch corners

High stressed elements are to
be modelled

2.2
Refining method
2.2.1
Two methods can be used for refining the high stressed areas:・ refined areas can be directly included in FE model used for the global cargo hold analysis of Ch 7, Sec 2 (SeeFig. 1).
・ detailed stresses in refined areas can be analysed by separate sub-models.
Fig. 1

Direct modeling with refined meshes

2.3
Modeling
2.3.1 Element type
Each structural members is to be modeled by using proper element type for the structure in accordance with theprinciple in Sec 2, 2.2.3. Orthotropic elements are not to be used in refined areas.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 3)

2.3.2 Mesh
The element size in refined areas is to be approximately one fourth of the representative spacing of ordinary
stiffeners in the corresponding area, i.e. 200 x 200 mm mesh size for structures whose ordinary stiffener spacing is
800 mm.
In addition, the web height of primary supporting members and web frames of single side bulk carriers is to be
divided at least into 3 elements.
The aspect ratio of element is not to exceed 3. Quad elements are to have 90 angles as much as practicable, or tohave angles between 45 and 135 .
2.3.3 Extent of sub-model
The minimum extent of sub-model is to be such that the boundaries of the sub-model correspond to the locations ofadjacent supporting members (see Fig. 2).
Fig. 2

Boundaries of sub-models

Model boundaries corresponding
to supporting member locations

2.4
Loading conditions
2.4.1
Loading conditions, which are applied to 3D FE model for the global cargo hold analysis according to Sec 2 andwhich induce stresses at considered locations exceeding the criteria specified in 2.1, are to be considered in thedetailed stress assessment.
2.5
Boundary conditions
2.5.1
Boundary conditions as specified in Sec 2, 2.3.1 are to be applied to the global cargo hold FE model with refined
meshes.
2.5.2
Nodal forces or nodal displacements obtained from the global cargo hold analysis of Sec 2 are to be applied to thesub-models. Where nodal forces are given, the supporting members located at the boundaries of a sub-model are to
be included in the sub-model. Where nodal displacements are given and additional nodes are provided in sub-models,
nodal displacements at the additional nodes are to be determined by proper interpolations.
3.

Analysis criteria

3.1
Allowable stress
3.1.1
Von Mises equivalent stresses in plate elements and axial stresses in line elements within refined areas are not toexceed 280/k N/mm2, where k is the material factor defined in Ch3, Sec 1.
In case elements significantly smaller than the size defined in 2.3.2 are used, this criteria applies to the average
stress of all elements included in an area corresponding to a single element having the size specified in 2.3.2.

－248－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 4)

Section 4

1.

HOT SPOT STRESS ANALYSIS FOR FATIGUE STRENGTHASSESSMENT

General1.1
Application
1.1.1
This Section describes the procedure to compute hot spot stresses for fatigue strength assessment of each location
specified in Ch 8, Sec 1, Table 1 by using finite element method.
1.1.2
The loading conditions and the load cases specified in 2.2 are to be considered for hot spot stress analysis.
2.

Analysis model

2.1
Modeling
2.1.1
Hot spot stresses for fatigue assessment are to be obtained by the global cargo hold models where the areas forfatigue assessment are modeled by very fine meshes, as shown in Fig. 1.
Alternatively, hot spot stresses can be obtained from sub-models, by using the similar procedures specified in Sec
3, 2.
2.1.2
Areas within at least a quarter of frame spacing in all directions from the hot spot position are to be modeled byvery fine meshes. The element size in very fine mesh areas is to be approximately equal to the representative net
thickness in the assessed areas, and the aspect ratio of elements is to be close to 1.
2.1.3
The mesh size is to be gradually changed from very fine mesh to fine mesh through the transition areas as shown in
Fig. 2. All structural members, including brackets, stiffeners, longitudinals and faces of transverse rings, etc., withintransition areas are to be modeled by shell elements with bending and membrane properties. Geometries of welds are
not to be modeled.
Fig. 1

Example of very fine mesh model(a) Part of global cargo hold model with very fine mesh－249－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 4)(b) Bilge hopper knuckle part(c) End of hold frameFig. 2(d) Longitudinal

Very fine mesh area, transition area and fine mesh area

Fine meshTransition

Very fine mesh

Fine mesh－250－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 4)

2.2
Loading conditions
2.2.1
The loading conditions, specified in Ch 8, Sec 1, Table 2 and illustrated in Ch 4, App 3, are to be considered.
2.2.2
Probability level of 10-4 is to be used for calculation of design loads.
2.3
Boundary conditions
2.3.1
The boundary conditions specified in Sec2, 2.3.1 are to be applied to the cargo hold model with localized very finemeshes or the mother model for sub-models. When using sub-models, nodal displacements or forces obtained fromthe mother model are to be applied to sub-models.
3.

Hot spot stress

3.1
Definition
3.1.1
The hot spot stress is defined as the structural geometric stress on the surface at a hot spot.
3.1.2
The hot spot stresses obtained by using superimposition method are to be modified according to Ch 8, Sec 3, 2.2
and 3.2.
3.2
Evaluation of hot spot stress
3.2.1
The hot spot stress in a very fine mesh is to be obtained using a linear extrapolation. The surface stresses located at
0.5 times and 1.5 times the net plate thickness are to be linearly extrapolated at the hot spot location, as described inFig. 3 and Fig.4.
The principal stress at the hot spot location having an angle with the assumed fatigue crack greater than 45 is to beconsidered as the hot spot stress.
Fig. 3

Definition of hot spot stress at an intersection of two plates

Hot spot stress
Thickness= t

0.5t
1.5t

－251－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 4)

Fig. 4

Definition of hot spot stress at an intersection of plating and bracket

Hot spot stress

Thickness= t

0.5t
1.5t
3.2.2
The hot spot stress at the intersection of two plates, as obtained from 3.2.1, is to be multiplied by the correction
factor l defined below, considering the difference between the actual hot spot location and assumed location and thedifference of stress gradient depending on the angle q, in deg, between the two plates, to be measured between 0 and
90 .
: q £ 75ìï0.8
l = í0.8 - 0.2 (q - 75) : 75 < q・ welded intersection between plane plates:ïî
15
・ welded intersection between bent plate and plane plate: l = 0.7 (i.e. bend type bilge knuckle part)
3.2.3
The hot spot stress in a non-welded area or along free edge is to be determined by extrapolating the principal
stresses of the two adjacent elements, as shown in Fig. 5.
Fig. 5

Definition of the hot spot stress along free edge
Free edge

Principal stress
Extrapolation
Hot spot stress

3.3
Simplified method for the bilge hopper knuckle part
3.3.1
At the bilge knuckle part, the hot spot stress hotspot may be computed by multiplying the nominal stressthe stress concentration factor Kgl defined in 3.3.3.
s hotspot = K gl s nominal－252－

nominal with

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 4)

3.3.2
The nominal stress at the hot spot location is to be determined by extrapolating the membrane stresses located at
1.5 times and 2.5 times the frame spacing from the hot spot location, as shown in Fig. 6.
Fig. 6

Definition of nominal stress at the bilge hopper knuckle part

:Nominal stress:Available data
1.5 frame spacings

2.5 frame spacings

3.3.3
The geometrical stress concentration factor Kgl for the bilge hopper knuckle part is given by the following
equation:
K gl = K 0 K 1 K 2 K 3 K 4
where:
K0 : Stress concentration factor depending on the dimensions of the considered structure, defined in Table 1
K1 : Correction coefficient depending on the type of knuckle connection, defined in Table 2
K2 : Correction coefficient depending on the thickness increment of the transverse web, defined in Table 2
or taken equal to 1.0 if there is no thickness increment
K3 : Correction coefficient depending on the insertion of horizontal gusset or longitudinal rib (see Fig. 7),
defined in Table 2 or taken equal to 1.0 if there is no horizontal gusset or longitudinal rib
K4 : Correction coefficient depending on the insertion of transverse rib, defined in Table 2 (see Fig. 8) or
taken equal to 1.0 if there is no transverse rib
Table 1
Plate net thickness
in FE model

Angle of hopper slope plate to the horizontal

(deg)

40

45

50

90

16

3.0

3.2

3.4

4.2

18

2.9

3.1

3.3

4.0

20

2.8

3.0

3.2

3.8

22

2.7

2.9

3.1

3.6

24

2.6

2.8

3.0

3.5

26

2.6

2.7

2.9

3.4

28

2.5

2.7

2.8

3.3

30

2.4

2.6

2.7

3.2

t (mm)

Note:

Stress concentration factor K0

Alternatively, K0 can be determined by the following formula.
0.14q (1.15 - 0.0033q )K0 =(0.5t ) ( 0.2 + 0.0028 q )－253－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Section 4)

Table 2Type of knuckle

K1

Weld Type

1.7
1.75 ;
2.80 ;

Bend Type

Correction coefficients
K2

K3

K4

0.9
0.9

R t<4
R t>8

0.85 ;
0.55 ;

R t<4
R t>8

0.9

Notes :The linear interpolation is applied between 4 £ R t £ 8
R denotes the radius of bend part and t denotes the plate thickness
In using the correction coefficient K2, the members should be arranged such that the bending deformation of the radius partis effectively suppressed.
The increase in web thickness is taken based on the plate thickness of the inner bottom plating.

Fig. 7

Example of insertion of horizontal gusset or longitudinal rib

Fig. 8

Example of insertion of transverse rib

about 500mm－254－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Appendix 1)

Appendix 1
1.

LONGITUDINAL EXTENT OF THE FINITE ELEMENT MODELS

Longitudinal extent

A three-hold length finite element model is recommended for the analysis, with the mid-hold as the target ofassessment.
The three-hold length finite element model reduces the adverse effects of the boundary conditions to a minimum inthe assessed mid-hold.
Fig. 1Longitudinal extent of the finite element model(Assessment target)

Fig. 2 Example of a finite element model－255－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Appendix 1)

2.

Typical Mesh
Fig. 3

Typical mesh of a web framesss : Spacing between longitudinal stiffeners

s

－256－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Appendix 2)

Appendix 2

DISPLACEMENT BASED BUCKLING ASSESSMENT IN FINITEELEMENT ANALYSES

SymbolsabxyCFor symbols not defined in this Section, refer to Ch 1, Sec 4.
: Length of the longer plate panel side
: Length of the shorter plate panel side
: Direction parallel to a, taken as the longitudinal direction: Direction parallel to b, taken as the transverse direction: Coefficient taken equal to:E
C=
For 4-node buckling panel:2(1 - n 2 )For 8-node buckling panel:C=E
4(1 - n 2 )n : Poisson ratiom : Coefficient taken equal to:m = 1-n1.

Introduction

1.1
1.1.1
This Appendix provides a method to obtain the buckling stresses and edge stress ratios for elementary plate panels(EPP) from a finite element calculation. This method is called Displacement Method .
2.

Displacement method

2.1
General
2.1.1
As the mesh of the finite elements does not correspond, in general, to the buckling panels the nodal points of the
EPP can be mapped onto the FE-mesh and the displacements of these nodes can be derived from the FE-calculation.
Whenever operations on displacements are performed, full numerical accuracy of the displacements should be
used.
2.1.2 4-node and 8-node panels
When the aspect ratio of the EPP is less than 3 and the variation of the longitudinal stresses in longitudinal
direction of the EPP is small, a 4-node panel may be used. Otherwise an 8-node panel is to be taken.
2.1.3 Calculation of nodal displacements
Three different node locations are possible:・ If a node of the buckling panel is located at an FE-node, then the displacements can be transferred directly.
・ If a node of the buckling panel is located on the edge of a plane stress element, then the displacements can belinearly interpolated between the FE-nodes at the edge.
・ If a node of the buckling panel is located inside of an element, then the displacements can be obtained usingbi-linear interpolation of all nodes of the element.
2.1.4 Transformation in local system
The transformation of the nodal displacements from the global FE-system into the local system of the buckling
panel is performed by(u ) = [l ] u g

( )

－257－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Appendix 2)

where:(u ) : Local displacement vectoru g : Global displacement vector( )[l] : Transformation matrix (2 3), of direction cosines of angles formed between the two sets of axes.
2.2
Calculation of buckling stresses and edge stress ratios
2.2.1
The displacements, derived at the corners of the elementary plate panel, are to be considered as input from which
the stresses at certain stress-points are derived. In the 4-node buckling panel these points are identical but in the
8-node buckling panel they differ. The locations and the numbering convention may be taken from Fig. 1 and Fig. 2.
The derived stresses at EPP corner nodes can be directly used as input for the buckling assessment according Ch 6,
Sec 3. The buckling load cases, which have to be considered in the FEM buckling assessment and defined in Ch 7 arebuckling load cases 1, 2 and 5 of Ch 6, Sec 3, Table 2 and 1a, 1b, 2 and 4 of Ch 6, Sec 3, Table 3. In special cases,
other buckling load cases may be used for the buckling assessment by a hand calculation.
2.2.2 4-node buckling panel
Stress displacement relationship for a 4-node buckling panel (compressive Stresses are positive)
Fig. 1

4-node buckling panel

a
4

3

vj

b

iy
2

1

uj
ix
From the displacements of the EPP corner nodes the stresses of these nodes can be obtained usingæ s 1*x ö00002v / b öæ - 2 / a - 2n / b 2 / a
ç
ç
*
0
0
0
0
2/b
ç s 1yç - 2n / a - 2 / b 2v / açç-m/b -m/ a
0
0
0
0
m/a
m/b
æ u1 ö
ç t1
çç
ç s 2*xç -2/a0
2 / a - 2n / b
02v / b
0
0
ç v1
ç *
ç
çu
2
/
0
2
/
2
/
0
2
/
0
0
n
a
v
a
b
b
ç s 2x
ç
ç 2
çt
ç
ç v2
0
/
/
/
/
0
0
0
m
a
m
b
m
a
m
b
ç 2* = -C çç- 2n / b 2 / a 2v / b - 2 / a000ç s 3x
ç 0
ç u3
çs *
ç 0
ç v3
- 2 / b 2v / a 2 / b - 2n / a
0
0
0
ç 3y
ç
ç
*
-m/b
- m / a çu4000m/b m/a
ç t3
ç 0
ç *
ç 0
- 2n / b
-2/a
0
0
2/a
0
2v / b çè v 4 øç s 4xçç s 4* yç 0-2/b- 2n / a 2 / b
00
2v / a
0
çç
ç
0
0
0
0
m/a
m / b - m / aø
è -m/bè t4 ø
where:(s1*x , s1*y , t1, L , s 4* x , s 4* y , t 4 )T = s *( )T(u1 , v1 ,L, u4 , v4 ) = (u )If both s

*
x

and s
*
x

*
y

: Element stress vector: Local node displacement vector

are compressive stresses then the stresses sx and sy must be obtained as follows:*ys x = (s - 0.3s ) / 0.91
s y = (s *y - 0.3s x* ) / 0.91

－258－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Appendix 2)

Where compressive stress fulfils the condition s *y < 0.3s x* , then s y = 0 and s x = s *x
Where compressive stress fulfils the condition s x* < 0.3s *y , then s x = 0 and s y = s *yThis leads to the following stress vector:(s ) = (s 1x , s 1 y , t 1 , L , s 4 x , s 4 y , t 4 ) T
Finally the relevant buckling stresses and edge stress ratios are obtained by:・ LC 1: longitudinal compression
æ s + s 4x s 2x + s 3x ö
s l = maxçç 1x
,
2
2
è
ø
1
(- s 1x + s 4 x - s 2 x + s 3 x )2s x = s l + 0 . 5 Ds l

Ds l =

y x = 1 - Ds l / s x
・ LC 2: transverse compression4

s t = 0.25å s iy
i =1

1
Ds t = - s 1 y - s 4 y + s 2 y + s 3 y2
s y = s t + 0 . 5 Ds t()

y y = 1 - Ds t / s y・ LC 5: shear
t +t +t +t
t= 1 2 3 4
4
2.2.3 8-node buckling panel
Stress displacement relationship for a 8-node buckling panel (compressive stresses are positive)
Fig. 2

8-node buckling panel(a) Displacement Nodes

a
4

8

7

3
b

1

2

5

a
4

uj

6

(b) Stress Nodes

6

3

b

1

vj

2

5

－259－

iy

ix

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 7 Appendix 2)

From the displacements of the EPP corner nodes the stresses of these nodes and on mid positions can be obtainedusing:
æ s 1*x ö000004n / b
12 / a
0
0
0
0
0
0
0 ö
æ - 12 / a - 4n / b
ç *
ç
0
0
0
0
0
4/b
12n / a
0
0
0
0
0
0
0
æ u1 ö
ç s 1yç - 12n / a - 4 / bççç - 2m / b - 6m / a00002m / b00
6m / a
0
0
0
0
0
0
ç v1
ç t1
ç
çu
*
çs 2x
0
0
12 / a - 4n / b
04n / b
0
0
0
0
0
0
0
0
0
- 12 / a
ç
ç 2
ç *
ç
a
b
b
a
0
0
12
/
4
/
0
4
/
0
0
0
0
12
/
0
0
0
0
0
n
n
ç v2
çs 2 y
ç
ç
çt
ç
0
0
0
0
0
0
0
0
0
0
0
0
- 2m / b 6m / a 2m / b- 6m / a
2
ç u3
ç *
ç
ç v3
b
a
b
a
0
0
0
4
/
12
/
4
/
0
0
0
0
0
0
12
/
0
0
0
n
n
s
ç 3x
ç
ç
çs *
ç
0
0
0
0
0
0
0
0
0
0
0
0
- 4 / b 12n / a 4 / b- 12n / a
çu4
y
3
ç
ç
çv
0
0
0
2m / b 6m / a
0
0
0
0
0
0
0
0
0
- 2m / b- 6m / a
ç t3
ç
ç 4
C
=
ç *
ç
0
0
0
0
0
4n / b00000012 / a0- 4n / b- 12 / a
çu5
çs 4x
ç
çv
*
çs 4 y
ç
0
0
0
0
0
4/b
0
0
0
0
0
0
12n / a0-4/b- 12n / a
ç 5
ç
ç
0
0
0
0
0
2m / b - 6m / a
0
0
0
0
0
0
0
6m / a ç u 6
ç t4
ç - 2m / b
ç
çs *
ç
0
0
0
0
0
0
0
0
12 / a02n / b02n / b ç v 6- 12 / a - 2n / b- 2n / bç 5* x
ç
çu7
a
b
a
b
b
b
0
0
0
0
0
0
0
0
12
/
2
/
12
/
2
/
0
2
/
0
2
/
n
n
s
ç 5y
ç
ç
çt
ç
m/b
m/b
0
0
0
0
0
0
0
0
6m / a00- m / b - 6m / a - m / b
ç v7
5
ç
ç
ç s 6*x
0
0
0
0
0
0
0
0
0
0
12 / a2n / b2n / b ç u 8- 2n / b- 2n / b- 12 / a
ç
ç
ç *
ç
çv
0
0
0
0
0
0
0
0
0
0
12n / a
2/b
2/b
-2/b
-2/b
- 12n / a
è 8ø
çs 6 y
ç
ç
çt
m
b
m
b
m
b
m
a
m
b
m
a
0
0
0
0
0
0
0
0
/
0
/
0
/
6
/
/
6
/
ø
è
è 6 ø

where:
s * = (s 1*x , s 1*y , t 1 , L , s 6*x , s 6* y , t 6 ) T( )(u ) = (u1x , v1 y , L , u 8 x , v 8 y ) T
If both s *x and s *y are compressive stresses then the stresses sx and sy must be obtained as follows:s x = (s x* - 0.3 s *y ) / 0.91
s y = (s *y - 0.3 s x* ) / 0.91
Where compressive stress fulfils the condition s *y < 0.3s x* , then s y = 0 and s x = s *x
Where compressive stress fulfils the condition s x* < 0.3s *y , then s x = 0 and s y = s *yThis leads to the following stress vector:(s ) = (s 1x , s 1 y , t 1 , L , s 6 x , s 6 y , t 6 ) T
The relevant buckling stresses can be obtained by:・ LC 1: longitudinal compression
æ s + s 4 x s 6 x + s 5 x s 2 x + s 3x ö
s l = maxçç 1x
,
,
2
2
2
è
ø
1
(s 4 x - s 1x + s 6 x - s 5 x + s 3 x - s 2 x )3s x = s l + 0.5 Ds l

Ds l =

y x = 1 - Ds l / s x
・ LC 2: transverse compression
1 6
s t = å s iy
6 i =1
1
Ds t = - s 1 y - s 4 y + s 2 y + s 3 y2
s y = s t + 0 . 5 Ds t()

y y = 1 - Ds t / s y・ LC 5: shear
ì t +t +t +t
t +t +t +t ü
t = max í 1 4 5 6 , 2 3 5 6 ý
4
4
î
þ

－260－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 1)

Chapter 8

FATIGUE CHECK OF STRUCTURAL DETAILS

Section 1
1.

GENERAL CONSIDERATION

General1.1
Application
1.1.1
The requirements of this Chapter are to be applied to ships having length LCSR-B of 150 m or above, with respect to25 years operation life in North Atlantic.
1.1.2
The requirements of this Chapter apply to fatigue cycles induced by wave loads. Fatigue induced by vibrations,low cycle loads or impact loads such as slamming, is out of the scope of this Chapter.
1.1.3
The requirements of this Chapter are applicable where steel materials have a minimum yield stress less than
400 N/mm2.
1.2
Net scantlings
1.2.1
All scantlings and stresses referred to in this Chapter are net scantlings obtained in accordance with Ch 3, Sec 2.
1.3
Subject members
1.3.1
Fatigue strength is to be assessed, in cargo hold area, for all the connected members at the considered locations
described in Table 1.
Table 1

Members and locations subjected to fatigue strength assessment

Members
Inner bottom plating
Inner side plating
Transverse bulkhead
Hold frames of single side bulk carriers

Details
Connection with sloping and /or vertical plate of lower stool
Connection with sloping plate of hopper tankConnection with sloping plate of hopper tankConnection with sloping plate of lower stool
Connection with sloping plate of upper stool
Connection to the upper and lower wing tankConnection of longitudinal stiffeners with web frames andOrdinary stiffeners in double side spacetransverse bulkhead
Connection of transverse stiffeners with stringer or similar

Ordinary stiffeners in upper and lower wing tankOrdinary stiffeners in double bottom
Hatch corners

2.

Connection of longitudinal stiffeners with web frames andtransverse bulkhead
Connection of longitudinal stiffeners with floors and floors in
way of lower stool or transverse bulkheadFree edges of hatch corners

Definitions

2.1
Hot spot
2.1.1
Hot spot is the location where fatigue crack may initiate.

－261－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 1)

2.2
Nominal stress
2.2.1
Nominal stress is the stress in a structural component taking into account macro-geometric effects but disregarding
the stress concentration due to structural discontinuities and to the presence of welds.
Nominal stresses are to be obtained either with the coarse mesh FE analysis specified in Ch 7, Sec 4, or with thesimplified procedure specified in Sec4.
2.3
Hot spot stress
2.3.1
Hot spot stress is defined as the local stress at the hot spot. The hot spot stress takes into account the influence ofstructural discontinuities due to the geometry of the connection but excludes the effects of welds.
Hot spot stresses are to be obtained either by fine mesh FE analysis specified in Ch 7, Sec 4, or by multiplying
nominal stresses by stress concentration factors defined in Sec 4.
2.4
Notch stress
2.4.1
Notch stress is defined as the peak stress at the weld toe taking into account stress concentrations due to the effectsof structural geometry as well as the presence of welds.
Notch stress is to be obtained by multiplying hot spot stress by fatigue notch factor defined in Sec 2, 2.3.1,
Table 1.
3.

Loading

3.1
Loading condition
3.1.1
The loading conditions to be considered are defined in Table 2 depending on the ship type. The standard loading
conditions illustrated in Ch 4, App 3 are to be considered.
Table 2
Ship type

Loading conditions

Full load condition
Homogeneous

Ballast condition

Alternate

Normal ballast

Heavy ballast

BC-A

ü

ü

ü

ü

BC-B

ü

---

ü

ü

BC-C

ü

---

ü

ü

3.2
Load case
3.2.1 Load cases
For each loading condition, the load cases to be considered, defined in Ch 4, Sec 4, 2, are:(a) H1 and H2 corresponding to the EDW H (head sea)(b) F1 and F2 corresponding to the EDW F (following sea)(c) R1 and R2 corresponding to the EDW R (beam sea)(d) P1 and P2 corresponding to the EDW P (beam sea)
3.2.2
In the case of fatigue assessment of hatch corners, only oblique sea is to be considered, taking into account thewave torsional moments defined in Ch 4, Sec 3, [3.4].
3.2.3 Predominant load case
From the above mentioned load cases and for each loading condition, the load case where the combined stressrange is maximum, corresponds to the predominant load case.

－262－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 2)

Section 2

FATIGUE STRENGTH ASSESSMENT

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Suffix which denotes load case H , F , R or P specified in Ch 4, Sec 4
i1 denotes load case H1 , F1 , R1 or P1 and i2 denotes load case H2 , F2 , R2 or P2(k): Suffix which denotes loading condition homogeneous condition , alternate condition , normal ballast
condition or heavy ballast condition as defined in Sec 1, Table 2
DsW , i(k) : Hot spot stress range, in N/mm2, in load case i of loading condition (k)smean , i(k) : Structural hot spot mean stress, in N/mm2, in load case i of loading condition (k)i1.

General1.1
Application
1.1.1
This Section gives the linear cumulative damage procedure for the fatigue strength assessment of this Chapter.
1.1.2
Fatigue strength is assessed based on an equivalent notch stress range obtained by multiplying an equivalent hot
spot stress range by a fatigue notch factor.
1.1.3
Hot spot stress ranges and hot spot mean stresses of primary members, longitudinal stiffeners connections andhatch corners are to be assessed respectively by Sec 3, Sec 4 and Sec 5.
1.1.4 Primary members and longitudinal stiffeners connections
Predominant load cases and condition 1 are to be obtained respectively in 2.1 and 2.2. The hot spot stress ranges
calculated in Sec 3 or Sec 4, corresponding to the predominant load case for each loading condition, are to be used in
2.3.2 to calculate the equivalent hot spot stress range.
1.1.5 Hatch corners
The hot spot stress range calculated in Sec 5 is to be used in 2.3.2 to calculate the equivalent hot spot stress range.
2.

Equivalent notch stress range

2.1
Predominant load case
2.1.1
The predominant load case I in fatigue assessment for each loading condition is the load case for which the
combined stress range for the considered member is the maximum among the load cases H , F , R and P
specified in Sec 1, 3.2.1.
D s W , I ( k ) = max D sW , i ( k )i()

where:

DsW , i (k) : Combined hot spot stress range, in N/mm2, defined either in Sec 3, 2.1.1, 2.2.1 or Sec 4, 2.3.1.
I: Suffix which denotes the selected predominant load case of loading condition (k) .
2.2
Loading condition 1
2.2.1
The condition 1 is the condition in which the maximum stress calculated by the equation below for theconsidered member is the largest on the tension side among the loading conditions homogeneous , alternate ,normal ballast and heavy ballast specified in Sec 1, Table 2.
DsW , I (k ) öæs max,1 = maxçç s mean, I ( k ) +
k
2
è
ø

－263－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 2)

where:

smean ,I (k) : Structural hot spot mean stress, in N/mm2, in predominant load case of loading condition (k)defined in 2.1.1
DsW , I (k) : Hot spot stress range, in N/mm2, in predominant load case of loading condition (k) defined in
2.1.1
2.2.2
Further to the determination of condition 1 according to 2.2.1, the corresponding loading condition is to beindexed with the suffix j equal 1.
2.3
Equivalent notch stress range
2.3.1 Equivalent notch stress range
The equivalent notch stress range, in N/mm2, for each loading condition is to be calculated with the following
formula:Ds eq, j = K f Ds equiv, jwhere:

Dsequiv , j : Equivalent hot spot stress range, in N/mm2, in loading condition j obtained by [2.3.2].
: Fatigue notch factor defined in Table 1.
Kf
Table 1

Fatigue notch factors Kf

Subject

Without weld grinding

With weld grinding(not applicable forordinary stiffeners andboxing fillet welding *1)

Butt welded joint

1.25

1.10

Fillet welded joint

1.30

1.15 *2

Non welded part

1.00

-

Note:
*1 Boxing fillet welding is defined as a fillet weld around a corner of a member as an extension of the principal weld.
*2 This is applicable for deep penetration welding, or full penetration welding only.
In case where grinding is performed, full details regarding grinding standards including the extent, smoothness particulars,
final welding profiles, and grinding workmanship as well as quality acceptance criteria are to be submitted to the Society for
approval.
It is preferred that any grinding is carried out by rotary burrs, is to extend below plate surfaces in order to remove any toe
defects and ground areas are to have sufficient corrosion protection.
Such treatments are to procedure smooth concave profiles at weld toes with the depth of these depressions penetrating into
plate surfaces to at least 0.5mm below the bottom of any visible undercuts.
The depth of any grooves produced is to be kept to a minimum and, in general, kept to a maximum of 1mm.
Under no circumstances is grinding depth to exceed 2mm or 7 % of plate gross thickness, whichever is smaller.
Grinding has to extend to 0.5 longitudinal spacing or 0.5 frame spacing at the each side of hot spot locations.

2.3.2 Equivalent hot spot stress range
The equivalent hot spot stress range, in N/mm2, is to be calculated for each loading condition with the following
formula:Ds equiv, j = f mean, j DsW , jwhere:
fmean , j:Correction factor for mean stress :・ for hatch corners fmean , j = 0.77
・ for primary members and longitudinal stiffeners connections, fmean , j corresponding to the condition
j taken equal to:－264－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 2)

0.25 üìé
æ 1 - ln 10 - 4 s m, j ö ù ïïç
f mean, j = max í0.4, êmax 0, +
ú ý
ç 2
4
Ds W , j øú ï
êë
ïî
è
û þ
2
Local hot spot mean stress, in N/mm , in the condition 1 , obtained from the following formulae:
・ if 0.6D s W , 1 ³ 2.5ReH :( )sm, 1 :s m , 1 = -0.18D s W , 1
・ if 0.6D s W , 1 < 2.5 ReH :sm , j :s m , 1 = ReH - 0.6D s W , 1

fors m, 1 = s mean,1 + s res

for0.6D s W , 1 > ReH - s res - s mean, 1
0.6D sW , 1 £ ReH - s res - s mean, 1
2Local hot spot mean stress, in N/mm , in the condition j , obtained from the following formulae:
・ if 0.24D s W , j ³ ReH :s m , j ( j¹1) = -0.18D s W , j
・ if 0.24D s W , j < ReH :s m , j ( j ¹1) = - ReH + 0.24D s W , j

for

0.24D s W , j > ReH + s m ,1 - s mean, 1 + s mean, js m, j ( j ¹1) = s m ,1 - s mean, 1 + s mean, jfor

0.24D s W , j £ ReH + s m ,1 - s mean, 1 + s mean, jsmean , j : Structural hot spot mean stress, in N/mm2, corresponding to the condition jsres : Residual stress, in N/mm2, taken equal to :s res = 0.25ReH for stiffener end connections res = 0
for non welded part and primary members(cruciform joint or butt weld)
3.

Calculation of fatigue damage

3.1
Correction of the equivalent notch stress range
3.1.1
The equivalent notch stress range is to be corrected with the following formula:
Ds E , j = f coat f material f thick Ds eq, jwhere:
fcoat : Correction factor for corrosive environment, taken equal to:fcoat = 1.05
for water ballast tanks and fuel oil tankfor dry bulk cargo holds and void spacefcoat = 1.03
fmaterial : Correction factor for material, taken equal to:1200
f material =965 + ReH
fthick: Correction factor for plate thickness, taken equal to 1.0 for hatch corners, flat bar or bulb stiffeners,
otherwise to be taken equal to:æ t ö
f thick = çè 22 ø
f thick = 1.0

0.25

for

t ³ 22 mmfort < 22 mmt: Net thickness, in mm, of the considered member, taken as the flange in case of stiffeners
Dseq , j : Equivalent notch stress range, in N/mm2, defined in 2.3.1.

3.2
Long-term distribution of stress range
3.2.1
The cumulative probability density function of the long-term distribution of combined notch stress ranges is to betaken as a two-parameter Weibull distribution:
x
é æ
ù
ö
x
F ( x) = 1 - expê- ç(
ln N R )ú
ê çè D s E , j øúëûwhere:
x : Weibull shape parameter, taken equal to 1.0－265－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 2)

NR : Number of cycles, taken equal to 104.
3.3
Elementary fatigue damage
3.3.1
The elementary fatigue damage for each loading condition is to be calculated with the following formula:a j N L Ds E , j 4 é æ 4
ö -3 æ 7
öùG ç + 1,n + n x g çç + 1,n ú
Dj=
4 ê ç
K (lnN ) x ë è x
ø
èx
øû
R

where:
K : S-N curve parameter, taken equal to 1.014 1015

aj : Coefficient taken equal to 1.0 for the assessment of hatch corners and depending on the loading
condition specified in Table 2 for primary members and longitudinal stiffeners connections.
NL : Total number of cycles for the design ship s life, taken equal to:
NL =0.85TL
4 log LCSR - B

TL : Design life, in seconds, corresponding to 25 years of ship s life, taken equal to 7.884 108
xæ 100.3 ö
ln N Rn =çç Ds E , jèø
G : Type 2 incomplete gamma function
g : Type 1 incomplete gamma function

Table 2LCSR - B < 200 m

LCSR - B ³ 200 m

4.

Coefficient aj depending on the loading condition
Loading Conditions

BC-A

BC-B, BC-C

Homogeneous

0.6

0.7

Alternate

0.1

---

Normal ballast

0.15

0.15

Heavy ballast

0.15

0.15

Homogeneous

0.25

0.5

Alternate

0.25

---

Normal ballast

0.2

0.2

Heavy ballast

0.3

0.3

Fatigue strength criteria

4.1
Cumulative fatigue damage
4.1.1
The cumulative fatigue damage D calculated for the combined equivalent stress is to comply with the following
criteria:
D = å D j £ 1.0
jwhere
Dj : Elementary fatigue damage for each loading condition j .

－266－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 3)

Section 3

STRESS ASSESSMENT OF PRIMARY MEMBERS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Suffix which denotes load case H , F , R or P specified in Ch 4, Sec 4
i1 denotes load case H1 , F1 , R1 or P1 and i2 denotes load case H2 , F2 , R2 or P2(k): Suffix which denotes loading condition, homogeneous condition , alternate condition , normal ballast
condition or heavy ballast condition as defined in Sec 1, Table 2
DsW , i(k) : Hot spot stress range, in N/mm2, in load case i of loading condition (k)smean , i(k) : Structural hot spot mean stress, in N/mm2, in load case i of loading condition (k) .
i

1.

General1.1
Application
1.1.1
Hot spot stress ranges and structural hot spot mean stresses of primary members are to be assessed according to therequirements of this Section, with the requirements given in Ch 7, Sec 4.
2.

Hot spot stress range

2.1
Stress range according to the direct method
2.1.1
The hot spot stress range, in N/mm2, in load case i of loading condition (k) is to be obtained from the following
formula:Ds W , i ( k ) = s W , i 1( k ) - s W , i 2 ( k )where:sW , i1(k), sW , i2(k) : Hot spot stress, in N/mm2, in load case i1 and i2 of loading condition (k) , obtainedby direct FEM analysis using fine mesh model specified in Ch 7, Sec 4.
2.2
Stress range according to the superimposition method
2.2.1 Hot spot stress range
The hot spot stress range, in N/mm2, in load case i of loading condition (k) is to be obtained from the following
formula:Ds W , i ( k ) = s GW , i 1( k ) + s LW , i 1( k ) - s GW , i 2( k ) + s LW , i 2( k )

(

) (

)

where:sLW , i1(k), sLW , i2(k) : Hot spot stress, in N/mm2, due to local loads in load cases i1 and i2 for loading
condition (k) obtained by the direct analysis using fine mesh FE model specified in
Ch 7, Sec 4
sGW , i1(k), sGW , i2(k) : Hot spot stress, in N/mm2, due to hull girder moments in load cases i1 and i2 forloading condition (k) obtained according to 2.2.2.
2.2.2 Stress due to hull girder moments
The hull girder hot spot stress, in N/mm2, in load cases i1 and i2 for loading condition (k) is to be obtained
from the following formula:( j = 1, 2)
s GW , i j ( k ) = CWV , i j s WV , i j - CWH , i j s WH , ( k )where:CWV , i1, CWV , i2, CWH , i1, CWH , i2 : Load combination factors for each load case defined in Ch 4, Sec 4, 2.2
sWV , i1 : Nominal hull girder stress, in N/mm2, in sagging condition induced by vertical wave bending
moment－267－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 3)

sWV , i1 =M WV , S ( z - N )
IY

10 -3

sWV , i2 : Nominal hull girder stress, in N/mm2, in hogging condition induced by vertical wave bending
moments WV , i 2 =M WV , H (z - N )
IY

10 -3

MWV , H, MWV , S : Vertical wave bending moments, in kN-m, in hogging and sagging conditions defined in
Ch 4, Sec 3, 3.1.1, with fp = 0.5
N: Z co-ordinate, in m, of the neutral axis, as defined in Ch 5, Sec 1z: Z co-ordinate, in m, of the point consideredsWH , (k) : Nominal hull girder stress, in N/mm2, induced by horizontal wave bending moment
MysWH , ( k ) = WH , ( k ) 10 -3
IZ
MWH , (k) : Horizontal wave bending moment, in kN-m, in loading condition (k) defined in Ch 4, Sec 3,[3.3.1], with fp = 0.5y: Y co-ordinate, in m, of the point considered, to be taken positive at port side and negative at
starboard side
IY, IZ : Net moments of inertia of hull cross-section, in m4, about transverse and vertical axis respectively,
as defined in Ch 5, Sec 1.
3.

Hot spot mean stress

3.1
Mean stress according to the direct method
3.1.1
The structural hot spot mean stress, in N/mm2, in load case i for loading condition (k) is to be obtained fromthe following formula:s+ s W , i 2( k )s mean, i ( k ) = W , i1( k )2
3.2
Mean stress according to the superimposition method
3.2.1 Hot spot mean stresses
The structural hot spot mean stress, in N/mm2, in load case i for loading condition (k) is to be obtained fromthe following formula:s+ s LW , i 2 ( k )s mean, i ( k ) = s GS , ( k ) + LW , i1( k )2where:
sGS , (k) : Hot spot mean stress, in N/mm2, due to still water hull girder moment in loading condition (k)obtained according to 3.2.2
s LW ,i1( k ) , s LW ,i 2( k ) : As defined in 2.2.1
3.2.2 Stress due to still water hull girder moment
The hot spot stress, in N/mm2, due to still water bending moment in loading condition (k) is to be obtained fromthe following formula:M(z - N ) -3
s GS , ( k ) = S , ( k )10IY
where:MS , (k) : Still water vertical bending moment, in kN-m, depending on the loading condition defined in Ch 4,
Sec 3, 2.2. If the design still water bending moments are not defined at a preliminary design stage,
still water bending moment in each loading condition may be obtained from the following formulae:
M S , (1) = -0.5 FMS M SW , S
homogeneous condition ;alternate condition ;M S , ( 2 ) = FMS M SW , H

normal ballast condition ;M S , (3) = FMS M SW , H－268－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 3)

heavy ballast condition ;xìM SW , Hï 2.66 L
CSR
B
ï
æ
x ö
ï
M SW , Hï 2.66çç 0.3 - L
CSR - B ø
è
ï
æ x
ö
ï
- 0.3 M SW , S
ï- 3.5çç Lè CSR - Bøï
M S , (4) = íæöxï- 3.5ç 0.7 M SW , SçLCSR - B øïèïï 2.66æç x - 0.7 ö M
SW , HçLïè CSR - Bøï
ï 2.66æç1 - x ö M
SW , Hçï
LCSR - B øèî; 0 < x £ 0.15LCSR - B; 0.15LCSR - B < x £ 0.3LCSR - B; 0.3LCSR - B < x £ 0.5 LCSR- B; 0.5LCSR - B < x £ 0.7 LCSR - B; 0.7 LCSR - B < x £ 0.85LCSR - B; 0.85LCSR - B < x £ LCSR -B

MSW,H, MSW,S : Permissible still water bending moment, in kN-m, in hogging and sagging conditions
FMS : Distribution factor defined in Ch 4, Sec 3, Fig. 2－269－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

Section 4

STRESS ASSESSMENT OF STIFFENERS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Suffix which denotes load case H , F , R or P specified in Ch 4, Sec 4
i1 denotes load case H1 , F1 , R1 or P1 and i2 denotes load case H2 , F2 , R2 or P2(k): Suffix which denotes loading condition, homogeneous condition , alternate condition , normal
ballast condition or heavy ballast condition as defined in Sec 1, Table 2
DsW , i(k) : Hot spot stress range, in N/mm2, in load case i of loading condition (k)smean , i(k) : Structural hot spot mean stress, in N/mm2, in load case i of loading condition (k)i1.

General1.1
Application
1.1.1
Hot spot stress ranges and structural hot spot mean stresses of longitudinal stiffeners are to be assessed in line withthe requirements of this Section.
1.1.2
The hot spot stress ranges and structural hot spot mean stresses of longitudinal stiffeners are to be evaluated at theface plate of the longitudinal considering the type of longitudinal end connection and the following locations.
(1) Transverse webs or floors other than those at transverse bulkhead of cargo hold or in way of stools, such that
additional hot spot stress due to the relative displacement may not be considered. These longitudinal end
connections are defined in Table 1. When transverse webs or floors are watertight, the coefficients Kgl and Kgh
as defined in Table 2 are to be considered instead of those defined in Table 1.
(2) Transverse webs or floors at transverse bulkhead of cargo hold in way of stools, such that additional hot spot
stress due to the relative displacement should be considered. These longitudinal end connections are defined inTable 2. When transverse webs or floors at transverse bulkhead of cargo hold or in way of stools are notwatertight, the coefficients Kgl and Kgh as defined in Table 1 are to be considered instead of those defined inTable 2.
2.

Hot spot stress range

2.1
Stress range obtained by the direct method
2.1.1
Hot spot stress ranges, in N/mm2, calculated with direct calculation for each load case H , F , R and P ofeach loading condition, are to be obtained according to Sec 3, 2.1.
2.2
Stress range according to the superimposition method
2.2.1
The hot spot stress ranges, in N/mm2, for each load case H , F , R and P of each loading condition according
to the superimposition method are to be obtained according to Sec 3, 2.2.
2.3
Stress range according to the simplified procedure
2.3.1 Hot spot stress ranges
The hot spot stress range, in N/mm2, due to dynamic loads in load case i of loading condition (k) is to beobtained from the following formula:
Ds W , i ( k ) = s GW , i1( k ) + s W 1, i1( k ) - s W 2, i1( k ) + s d , i1( k ) - s GW , i 2( k ) + s W 1, i 2( k ) - s W 2, i 2( k ) + s d , i 2( k )

(

) (

where

sGW , i1(k), sGW , i2(k) : Stress due to hull girder moment, defined in 2.3.2
－270－

)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

sW1 , i1(k), sW1 , i2(k): Stress sLW, i j(k), sCW, i j (k) and sLCW, i j(k) due to hydrodynamic or inertial pressure when thepressure is applied on the same side as the ordinary stiffener depending on theconsidered casesW2, i1(k), sW2, i2(k) : Stress sLW, i j(k), sCW, i j(k) and sLCW, i j(k) due to hydrodynamic or inertial pressure when thepressure is applied on the side opposite to the stiffener depending on the considered casesLW, i1(k), sLW, i2(k) : Stresses due to wave pressure, defined in 2.3.3
sCW, i1(k), sCW, i2(k) : Stresses due to liquid pressure, defined in 2.3.4
sLCW, i1(k), sLCW, i2(k) : Stresses due to dry bulk cargo pressure, defined in 2.3.5
sd, i1(k), sd, i2(k): Stress due to relative displacement of transverse bulkhead or floor in way of stools,
defined in 2.3.6.
2.3.2 Stress due to hull girder moments
The hull girder hot spot stress, in N/mm2, in load case i1 and i2 for loading condition (k) is to be obtained
from the following formula:s GW , i j ( k ) = K gh (CWV , i j s WV , i j - CWH , i j s WH , ( k ) )( j = 1, 2)
where:Kgh : Geometrical stress concentration factor for nominal hull girder stress Kgh is given in Table 1 and Table
2 for the longitudinal end connection specified in 1.1.2 (1) and 1.1.2 (2), respectively.
The stress concentration factor can be evaluated directly by the FE analysis.
CWV, i1, CWV, i2, CWH, i1, CWH, i2 : Load combination factors for each load case defined in Ch 4, Sec 4, 2.2.
sWV , i1, sWV , i2, sWH , (k): Nominal hull girder stresses, in N/mm2, defined in Sec 3, 2.2.2.
2.3.3 Stress due to wave pressure
The hot spot stress, in N/mm2, due to the wave pressure in load case i1 and i2 for loading condition (k) is tobe obtained from the following formula:æ 6x f 6x f 2 ö
K gl K s pCW , i j ( k ) sl 2 ç1 + 2
ç
l
l ø 3
è
( j = 1, 2)
s LW , i j ( k ) =10
12w
ìï2C NE ,i1( k ) pW ,i1( k ) ; C NE ,i1( k ) < 0.5
pCW ,i1( k ) = í; C NE ,i1( k ) ³ 0.5
ïî pW ,i1( k )ìï0pCW ,i 2( k ) = íïî(2C NE ,i 2( k ) - 1) pW ,i 2( k ); C NE ,i 2( k ) < 0.5; C NE ,i 2( k ) ³ 0.5

where:
pW , i j(k) : Hydrodynamic pressure, in kN/m2, specified in Ch 4, Sec 5, 1.3, 1.4 and 1.5, with fp = 0.5, in loadcase i1 and i2 for loading condition (k) . When the location of the considered member isabove the waterline, the hydrodynamic pressure is to be taken as the pressure at waterline.
Kgl : Geometrical stress concentration factor for stress due to lateral pressure Kgl is given in Table 1 andTable 2 for the longitudinal end connection specified in 1.1.2 (1) and 1.1.2 (2), respectively.
The stress concentration factor can be evaluated directly by the FE.
Ks : Geometrical stress concentration factor due to stiffener geometry
é t f (a 2 - b 2 ) ù éb æw ö ù -3
K s =1 + êú ê1 - çç1 + b ú 10
wa ø úû
2wbêë
úû êë b f èa, b : Eccentricity, in mm, of the face plate as defined in Fig. 1. For angle profile, b is to be taken as half
the net actual thickness of the web.
tf, bf : thickness and breadth of face plate, in mm, respectively, as defined in Fig. 1.
wa, wb : Net section modulus in A and B respectively(see Fig. 1), in cm3, of the stiffener about the neutral
axis parallel to Z axis without attached plating.
CNE , i j(k) : Correction factor for the non linearity of the wave pressure range in load case i1 and i2 ofloading condition (k)－271－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

2.5
ì é æ
pW , i j ( k ), WL ö ùúï ê çï ê ç z - TLC ( k ) +pW , i j ( k ), WLúrgïexpê- çú for z > TLC ( k ) rgpïúC NE , i j ( k ) = í êê çç W , i j ( k ), WL (- ln 0.5)-1 2.5úrgï êë èø ûúïpW , i j ( k ), WL
ï
for z £ TLC ( k ) ï 1 .0
rg
îTLC(k) : Draught, in m, of the considered loading condition (k)pW , i j(k), WL : Hydrodynamic pressure, in kN/m2, at water line in load case i1 and i2 of loading condition(k)z : Z co-ordinate, in m, of the point considereds : Stiffener spacing, in ml : Span, in m, to be measured as shown in Fig. 2. The ends of the span are to be taken at points where thedepth of the end bracket, measured from the face plate of the stiffener is equal to half the depth of thestiffener
xf : Distance, in m, to the hot spot from the closest end of the span l (see Fig. 2)
w : Net section modulus, in cm3, of the considered stiffener. The section modulus w is to be calculated
considering an effective breadth se, in m, of attached plating obtained from the following formulae:ìé p æ l 1 - 1 / 3 öùl6
ï0.67 s sin ê ç
£
ú for
ç
ï
2s
s 1-1/ 3
êë 6 èø úû
se = í
l6
ï0.67 s>forï
s 1 - 1/ 3
î()

Fig. 1

Sectional parameters of a stiffener
Z
bf
tf

b

a

B

A
tw

hw
tp
X

O

bp

Fig. 2

Span and hot spot of longitudinal stiffeners

Trans.

Trans.
hot spot

xf

l

－272－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

Trans.

Trans.
hot spot

d/2

d/2
d
xf

l

Trans.

Trans.
hot spotll
2.3.4 Stress due to liquid pressure
The hot spot stress, in N/mm2, due to the liquid pressure in load case i1 and i2 for loading condition (k) is tobe obtained from the following formula:æ 6 x f 6x f 2 ö
K gl K s C NI , i j ( k ) p BW , i j ( k ) sl 2 ç1 + 2
ç
l
l ø
è
( j = 1, 2)
s CW , i j ( k ) =10 3
12w
where:
pBW , i j(k) : Inertial pressure, in kN/m2, due to liquid specified in Ch 4, Sec 6, 2.2, with fp = 0.5, in load casei1 and i2 for loading condition (k) . Where the considered location is located in fuel oil,other oil or fresh water tanks, no inertial pressure is considered for the tank top longitudinals andwhen the location of the considered member is above the liquid surface in static and uprightcondition, the inertial pressure is to be taken at the liquid surface line.
CNI , i j(k) : Correction factor for the non linearity of the inertial pressure range due to liquid in load case i1
and i2 for loading condition (k)
2.5
ì é æ
ö ù
p
BW
,
i
j
(
k
),
SF
ï ê ç z zú- SF +ï ê çp BW , i j ( k ), SFúrgïexp ê- çú for z > z SF rgpïúC NI , i j ( k ) = í êê çç BW , i j ( k ), SF (- ln 0.5)-12.5úrgï ëê èø ûúïp BW , i j ( k ), SFï
for z £ z SF ï 1 .0
rg
îzSF
: Z co-ordinate, in m, of the liquid surface. In general, it is taken equal to zTOP defined in Ch 4
Sec 6. If the considered location is located in fuel oil, other oil or fresh water tanks, it may betaken as the distance to the half height of the tank.
z: Z co-ordinate, in m, of the point consideredpBW, i j(k), SF : Inertial pressure due to liquid, in kN/m2, taken at the liquid surface in load case i1 and i2 forloading condition (k) . In calculating the inertial pressure according to Ch 4 Sec 6, 2.2.1, x andy coordinates of the reference point are to be taken as liquid surface instead of tank top.

－273－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

Kgl, Ks: the stress concentration factor defined in 2.3.3
2.3.5 Stress due to dry bulk cargo pressure
The hot spot stress, in N/mm2, due to the dry bulk cargo pressure in load case i1 and i2 for loading condition(k) is to be obtained from the following formula:æ 6 x f 6x f 2 ö
K gl K s pCW , i j ( k ) sl 2 ç1 + 2
ç
l
l ø 3
è
s LCW , i j ( k ) =10( j = 1, 2)
12w
where:
pCW , i j(k) : Inertial pressure, in kN/m2, due to dry bulk cargo specified in Ch 4, Sec 6, 1.3 for a cargo density
rC specified in Ch 4, Appendix 3, and with fp = 0.5, in load case i1 and i2 for loading
condition (k)2.3.6 Stress due to relative displacement of transverse bulkhead or floor in way of transverse bulkhead or stool
For longitudinal end connection specified in 1.1.2 (2), the additional hot spot stress, in N/mm2, due to the relative
displacement in the direction perpendicular to the attached plate between the transverse bulkhead or floor in way ofstools and the adjacent transverse web or floor in load case i1 and i2 for loading condition (k) is to be obtained
from the following formula:ìK dF -a s dF - a , i j ( k ) + K dA-a s dA- a , i j ( k ) for point " a"s d , i j (k ) = í( j = 1, 2)
îK dF - f s dF - f , i j ( k ) + K dA- f s dA- f , i j ( k ) for point " f "where:
a, f : Suffix which denotes the location considered as indicated in Table 2
A, F : Suffix which denotes the direction, forward (F) and afterward (A), of the transverse web or floor
where the relative displacement is occurred as indicated in Table 2 (see Fig. 3)
sdF-a, i j(k), sdA-a, i j(k), sdF-f, i j(k), sdA-f, i j(k) : Additional stress at point a and f , in N/mm2, due to the relative
displacement between the transverse bulkhead or floors in way ofstools and the forward (F) and afterward (A) transverse web or floor
respectively in load case i1 and i2 for loading condition (k)æx fA ö -5
3.9d F , i j ( k ) EI A I F ç
1 - 1.15
10s dF -a, i j ( k ) =wAl F (l A I F + l F I A ) çlAèøé 3.9dùæöA, i j ( k ) EI A I F
ç1 - 1.15 x fA - 0.9d A, i j ( k ) EI A x fA ú 10 -5
s dA-a , i j ( k ) = ê3lAê wA l A (l A I F + l F I A ) ç
ú
wAl A
è
ø
ë
û
é 3.9dùæöF , i j ( k ) EI A I F
ç1 - 1.15 x fF - 0.9d F , i j ( k ) EI F x fF ú 10 - 5
s dF - f , i j ( k ) = ê3ê w F l F (l A I F + l F I A ) çúlF
wF l Fèøëû
x fF ö - 5
3.9d A, i j ( k ) EI A I F æç
1 - 1.15
10s dA- f , i j ( k ) =w F l A (l A I F + l F I A ) çlFèødF, i j(k), dA, i j(k) : Relative displacement, in mm, in the direction perpendicular to the attached plate between
the transverse bulkhead or floor in way of stools and the forward (F) and afterward (A)transverse web or floor in load case i1 and i2 for loading condition (k) (see Fig. 3)(a) For longitudinals penetrating floors in way of stools
Relative displacement is defined as the displacement of the longitudinal in relation to the line
passing through the stiffener end connection at the base of the stool measured at the first floor
forward (F) or afterward (A) of the stool.
(a) For longitudinals other than (a)Relative displacement is defined as the displacement of the longitudinal in relation to its original
position measured at the first forward (F) or afterward (A) of the transverse bulkhead.
Where the stress of the face of longitudinal at the assessment point due to relative displacement is
tension, the sign of the relative displacement is positive.
IF, IA: Net moment of inertia, in cm4, of forward (F) and afterward (A) longitudinal－274－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

KdF-a, KdA-a, KdF-f, KdA-f : Stress concentration factor for stiffener end connection at point a and f subject
to relative displacement between the transverse bulkhead and the forward (F) andafterward (A) transverse web or floors in way of stool respectively as defined inTable 2. The stress concentration can be evaluated directly by the FE analysis
when the detail of end connection is not defined in Table 2.
lF, lA : Span, in m, of forward (F) and afterward (A) longitudinal to be measured as shown in Fig. 2
xfF, xfA : Distance, in m, to the hot spot from the closest end of lF and lA respectively (see Fig. 2).
Fig. 3

Definition of the relative displacement (Example of the side longitudinal)

Aft

Fore
IA

dA

IF

a

lA
T. BHD

Trans.

3.

dF

f

lF
Trans.

Hot spot mean stress

3.1
Mean stress according to the direct method
3.1.1
The structural hot spot mean stress, in N/mm2, in each loading condition calculated with the direct method is to beobtained according to Sec 3, 3.1.
3.2
Mean stress according to the superimposition method
3.2.1
The structural hot spot mean stress, in N/mm2, in each loading condition calculated with the superimposition
method is to be obtained according to Sec 3, 3.2.
3.3
Mean stress according to the simplified procedure
3.3.1 Hot spot mean stresses
The structural hot spot mean stress, in N/mm2, in loading condition (k) regardless of load case i is to beobtained from the following formula:s mean, ( k ) = s GS , ( k ) + s S1, ( k ) - s S 2, ( k ) + s dS , ( k )wheresGS, (k) : Stress due to still water hull girder moment, defined in 3.3.2
sS1, (k) : Stress due to static pressure when the pressure is applied on the same side as the ordinary stiffener
depending on the considered case, with consideration of the stresses defined in 3.3.3 to 3.3.5
sS2, (k) : Stress due to static pressure when the pressure is applied on the side opposite to the stiffener
depending on the considered case, with consideration of the stresses defined in 3.3.3 to 3.3.5
sdS, (k) : Stress due to relative displacement of transverse bulkhead in still water, defined in 3.3.6.
3.3.2 Stress due to still water hull girder moment
The hot spot stress due to still water bending moment, in N/mm2, in loading condition (k) is to be obtained withthe following formula:s GS , ( k ) = K gh

M S , ( k ) (z - N )
IY

10 -3

where:MS, (k) : Still water vertical bending moment, in kN-m, defined in Sec 3, 3.2.2.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

3.3.3 Stress due to hydrostatic and hydrodynamic pressure
The hot spot stress due to hydrostatic and hydrodynamic pressure, in N/mm2, in loading condition (k) is to beobtained with the following formula:2
pCW , i 1( k ) + pCW , i 2 ( k ) ü 2 æ 6 x f 6 x f öì+ 2
K gl K s í p S , ( k ) +ý sl çç1 2
l
l ø
þ è
î
s LS , ( k ) =10 3
12w
where:
pS, (k) : Hydrostatic pressure, in kN/m2, in loading condition (k) specified in Ch 4, Sec 5, 1.2.
pCW,ij (k) : Corrected hydrodynamic pressure, in kN/m2, according to 2.3.3, with fp = 0.5, in load case i1 andi2 for loading condition (k) .
i: Suffix which denotes the load case specified in Sec 2 [2.1.1], when calculating the mean stress, "I" is to
be used.
3.3.4 Stress due to liquid pressure in still water
The structural hot spot mean stress due to liquid pressure in still water, in N/mm2, in loading condition (k) is tobe obtained with the following formula:æ 6x f 6x f 2 ö
K gl K s pCS , ( k ) sl 2 ç1 + 2
ç
l
l ø 3
è
s CS , ( k ) =10
12w
where:
pCS, (k) : Liquid pressure in still water, in kN/m2, in loading condition (k) specified in Ch 4, Sec 6, 2.1.
Where the considered location is located in fuel oil, other oil or fresh water tanks, dAP and PPV defined in Ch 4 Sec
6 are to be taken equal to 0 and zTOP specified in Ch 4 Sec 6, 2.1 is to be taken equal to zSF specified in 2.3.4.
3.3.5 Stress due to dry bulk cargo pressure in still water
The structural hot spot mean stress due to dry bulk cargo pressure in still water, in N/mm2, in loading condition(k) is to be obtained with the following formula:æ 6x f 6x f 2 ö2çK gl K s pCS , ( k ) sl 1 + 2
ç
l
l ø 3
è
s LCS , ( k ) =10
12w
where:
pCS, (k) : Dry bulk cargo pressure in still water, in kN/m2, in loading condition (k) specified in Ch 4, Sec6, 1.2
3.3.6 Stress due to relative displacement of transverse bulkhead in still water
The additional hot spot mean stress, in N/mm2, due to the relative displacement in the transverse direction between
the transverse bulkhead and the adjacent transverse web or floor in loading condition (k) , is to be obtained with thefollowing formula:ì K dF - a s dSF - a , ( k ) + K dA- a s dSA- a , ( k ) for point as dS , ( k ) = íî K dF - f s dSF - f , ( k ) + K dA- f s dSA- f , ( k ) for point f
where:

sdSF-a, (k), sdSA-a, (k), sdSF-f, (k), sdSA-f, (k) : Additional stress at point a and f , in N/mm2, due to the relative
displacement between the transverse bulkhead and the forward (F) andafterward (A) transverse web or floor respectively in loading condition(k)s dSF -a , ( k ) =öæ
ç1 - 1.15 x fA 10 -5
wAl F (l A I F + l F I A ) çlAèø
3.9d SF , ( k ) EI A I F

é 3.9dùæöSA, ( k ) EI A I F
ç1 - 1.15 x fA - 0.9d SA, ( k ) EI A x fA ú 10 -5
s dSA-a , ( k ) = ê3lAê w Al A (l A I F + l F I A ) çú
wA l A
è
ø
ë
û

－276－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

é 3.9dùæöSF , ( k ) EI A I F
ç1 - 1.15 x fF - 0.9d SF , ( k ) EI F x fF ú 10 -5
s dSF - f , ( k ) = ê3lFê wF l F (l A I F + l F I A ) çú
wF l Fèøëû
x fF ö -5
3.9d SA, ( k ) EI A I F æç
1 - 1.15
10
s dSA- f , ( k ) =wF l A (l A I F + l F I A ) çlFèødSF, (k), dSA, (k) : Relative displacement, in mm, in still water in the transverse direction between the transverse
bulkhead and the forward (F) and afterward (A) transverse web or floor respectively inloading condition (k)－277－2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

Table 1Stress concentration factors for non-watertight longitudinal end connection at transverse webs or floors
other than transverse bulkheads or floors in way of stools
Assessed

Bracket type

point

Bracket size

Stress concentration factors
Kgl

Kgh

-----

1.65

1.1

dw £ d<1.5dw

1.55

1.1

1.5dw £ d

1.5

1.05

dw £ d<1.5dw

1.5

1.1

1.5dw £ d

1.45

1.05

dw £ d<1.5dw

1.4

1.1

1.5dw £ d

1.4

1.05

dw £ d<1.5dw

1.35

1.1

1.5dw £ d

1.35

1.05

dw £ d<1.5dw

1.15

1.05

1.5dw £ d

1.1

1.05

dw

1

AftA

FFore
f

a

a

dw

2

AftA

F Fore
f

a

a

d
3

F

A

f

a

a

dw

4

AftA

F Fore
f

a

f

d
dw

5

AftA

F Fore
f

a

f

d
dw

6

AftA

F Fore
f

a

d

a

d

－278－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

Table 1Stress concentration factors for non-watertight longitudinal end connection at transverse webs or floors
other than transverse bulkheads or floors in way of stools (continued)
Assessed

Bracket type

point

Bracket size

Stress concentration factors
Kgl

Kgh

dw £ d<1.5dw

1.15

1.05

1.5dw £ d

1.1

1.05

dw £ d<1.5dw

1.1

1.1

1.5dw £ d

1.05

1.05

a

d £ 2h

1.45

1.1

a

d £ 2.5h

1.35

1.1

a

d1 £ 2h

1.15

1.1

1.85

1.1

1.15

1.1

1.35

1.1

1.1

1.1

2.05

1.1

1.1

1.1

1.8

1.1

7

A

F
f

a

dw

8

AftA

F Fore
f

a

d

d

A

F

10

d

F

A

f

a

Tripping
bracketdh11Tripping
bracket

f

a
h

F

A

h £ d2fad1 £ 2.5h
and

f

d1

A

h

F

h £ d2fad1 £ 2h
and

f

a

d2
14
Tripping
brackethFaTripping
bracket

d1

A

d2
13

and

f

a

d2
12
Tripping
bracket

a

d1

A

h

h £ d2

f

F
a

a

d2

d1

d1 £ 2.5hf9Tripping
bracketaandhh £ d2f－279－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

Table 2Stress concentration factors for watertight longitudinal end connection at transverse bulkheads and floors
in way of stools
Assessed

Bracket type

point

Bracket size

Kgl

Stress concentration factors
Kgh
KdF

KdA

1
A

F

2

a

-----

1.5

1.1

1.15

1.5

f

-----

1.1

1.05

1.55

1.05

dw £ d<1.5dw

1.45

1.1

1.15

1.4

1.5dw £ d

1.4

1.05

1.15

1.35

dw £ d<1.5dw

1.1

1.05

1.15

1.1

1.5dw £ d

1.05

1.05

1.1

1.05

dw £ d<1.5dw

1.4

1.1

1.1

1.35

1.5dw £ d

1.35

1.05

1.05

1.3

dw £ d<1.5dw

1.05

1.05

1.1

1.05

1.5dw £ d

1.05

1.05

1.05

1.05

dw £ d<1.5dw

1.1

1.05

1.05

1.25

1.5dw £ d

1.05

1.05

1.05

1.2

dw £ d<1.5dw

1.3

1.1

1.35

1.05

1.5dw £ d

1.3

1.05

1.3

1.05

dw £ d<1.5dw

1.1

1.05

1.05

1.2

1.5dw £ d

1.05

1.05

1.05

1.15

dw £ d<1.5dw

1.3

1.1

1.55

1.1

1.5dw £ d

1.3

1.05

1.5

1.05

dw £ d<1.5dw

1.1

1.05

1.05

1.1

1.5dw £ d

1.05

1.05

1.05

1.05

dw £ d<1.5dw

1.05

1.05

1.1

1.05

1.5dw £ d

1.05

1.05

1.05

1.05

dw
AftA

FFore
a

f

a

f

d
3
A

F
a

f

a

f
4

dw
Aft A

a

a

f

FFore

f

d
5

dw
AftA

FFore

a

f

a

f

d
6

dw
AftA

FFore

a

f

a

d

d

f

－280－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 4)

Table 2Stress concentration factors for watertight longitudinal end connection at transverse bulkheads and floors
in way of stools (continued)
Assessed

Bracket type

point

7

F

A

Bracket size

Kgl

Stress concentration factors
Kgh
KdF

KdA

dw £ d<1.5dw

1.1

1.05

1.05

1.2

1.5dw £ d

1.05

1.05

1.05

1.15

dw £ d<1.5dw

1.05

1.05

1.05

1.05

1.5dw £ d

1.05

1.05

1.05

1.05

dw £ d<1.5dw

1.1

1.1

1.05

1.15

1.5dw £ d

1.05

1.05

1.05

1.1

dw £ d<1.5dw

1.05

1.05

1.1

1.05

1.5dw £ d

1.05

1.05

1.05

1.05

1.4

1.05

1.05

1.75

f

1.6

1.05

1.7

1.05

a

1.3

1.05

1.05

1.75

1.55

1.05

1.3

1.05

1.1

1.05

1.05

1.2

1.75

1.05

1.4

1.05

1.1

1.05

1.05

1.2

1.3

1.05

1.05

1.05

1.05

1.05

1.05

1.15

1.95

1.05

1.55

1.05

1.05

1.05

1.05

1.15

1.7

1.05

1.15

1.05

a

f

dw

8

Aft A

FFore
f

a

d
AftA

FFore
f

a

F

A
a

Tripping
bracket11
Aft A
Tripping
bracket

FFore
a

dd11

h

f

h £ d2

F

A

a

h

d1

d1 £ 2.5h
and

f

a
d2

f

h £ d2FA

aTripping
bracketd1 £ 2h
and

d2

h

d1

f

a

d1

h

d1 £ 2.5h
and

f
d2

h £ d2FA
aTripping
bracketd1 £ 2h
and

f

a
dd2

14

d £ 2.5h
f

d

h

13

d £ 2hdd

h12Tripping
bracketfaTripping
bracket

10

d

f

9

a

f

h £ d2－281－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 5)

Section 5
1.

STRESS ASSESSMENT OF HATCH CORNERS

General1.1
Application
1.1.1
Hot spot stress ranges and structural hot spot mean stresses of hatch corners based on the simplified procedure are
to be assessed according to the requirements of this Section.
2.

Nominal stress range

2.1
Nominal stress range due to wave torsional moment
2.1.1
The nominal stress range, in N/mm2, due to cross deck bending induced by wave torsion to be obtained from thefollowing formula:
Q BH
2
Ds WT =
FS FL
WQ
1000
where:
Q=

1000 u(B H + b S )3
12 EI Qu+

2 .6 B H
EAQ: Displacement of hatch corner in longitudinal direction, in m, taken equal to:
31.2 M WT w
u=1000 I T E DOC

DOC : Deck opening coefficient, taken equal to:
L B
DOC = n C
å LH ,i BH ,ii =1

MWT : Maximum wave torsional moment, in kN-m, defined in Ch 4, Sec 3, 3.4.1, with fp = 0.5
FS : Stress correction factor, taken equal to:
FS = 5FL: Correction factor for longitudinal position of hatch corner, taken equal to:x
for 0.57 £ x / LCSR -B £ 0.85
FL = 1.75
LCSR - B
FL = 1.0
for x/LCSR-B < 0.57 and x/LCSR-B > 0.85

BH
WQ

: Breadth of hatch opening, in m
: Section modulus of the cross deck about z-axis, in m3, including upper stool, near hatch corner (seeFig. 2): Moment of inertia of the cross deck about z-axis, in m4, including upper stool, near the hatch corner(see Fig. 2): Effective shear area of the whole section of the cross deck, in m2, including upper stool, near thehatch corner (see Fig. 2). For the determination of the effective shear area the consideration of only
the plate elements is sufficient, and the stiffeners can be neglected.
: Breadth of remaining deck strip on one side, in m, beside the hatch opening: Torsion moment of inertia of ships cross section, in m4, calculated within cross deck area by
neglecting upper and lower stool of the bulkhead (see Fig. 1). It may be calculated according to App1
: Sector coordinate, in m2, calculated at the same cross section as IT and at the Y and Z location of thehatch corner (see Fig. 1) It may be calculated according to App1
: Length of cargo area, in m, being the distance between engine room bulkhead and collision bulkhead

IQ
AQ

bS
IT

LC

－282－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 5)

BH,i : Breadth of hatch opening of hatch i, in m
LH,i : Length of hatch opening of hatch i, in mn
: Number of hatches.
Fig. 1

Cross section for determination of IT and
Z

Location of hatch corner point
for determination of w

Y

Fig. 2Elements to be considered for the determination of AQ, WQ and IQ

Z
Y

2.2
Nominal mean stress
2.2.1
The mean stress due to still water bending moment within the cross deck is set to 0.
3.

Hot spot stress

3.1
Hot spot stress range
3.1.1
The hot spot stress range, in N/mm2, is to be obtained from the following formula:
Ds W = K gh Ds WT
where:Kgh : Stress concentration factor for the hatch corner, taken equal to:－283－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Section 5)

r + 2rb
K gh = a
3ra

ra :
rb :
l CD :
b :

0.65
ìï æ
0.22l CD ö üï2b
í1 + çç
ý , to be taken not less than 1.0raø ïþïî è 1.23lCD + 1.6b

Radius, in m, in major axis
Radius, in m, in minor axis ( if the shape of corner is a circular arc, rb is to be equal to ra)
Length of cross deck, in m, in longitudinal direction
Distance, in m, from the edge of hatch opening to the ship s side.

－284－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Appendix 1)

Appendix 1
1.

CROSS SECTIONAL PROPERTIES FOR TORSION

Calculation Formulae

1.1
Torsion Function
1.1.1
For any partial area of closed cells the following geometric figures and ratios have to be computed:
1
Ay = ( zi + z k )( yk - yi )2l = ( y k - yi ) 2 + ( z k - zi ) 2

s l
=
t t

Fig.1
z
k
i

i

zi
0

Ay

zk

yk

yi

t

y

The following three versions of algorithms may be applied depending on the type of cross section:
Version A : Asymmetric open cross sections as shown in Fig. 2
Version B : Symmetric cross sections with particular closed cells (closed cells without shared walls) as
shown in Fig. 3. In this case the torsion function can be calculated for each cell separately.
2 å Ay2 å AyCell 0F0 =;F 2 = Cell 2ssååCell 0 t
Cell 2 t
Version C : Symmetric cross sections with multiple closed cells (closed cells with shared walls) as shown in
Fig. 4. In this case the torsion function for each cell i can be calculated by solving a linear
system of equations considering the shared walls.
sæsö= 2 ACell 0
F 0 å + F1 çè t øCommon Wall
Cell 0 tsæsö
F1 å + F 0 ç= 2 ACell1
è t ø Common Wall
Cell 1 t

From this system of equations the torsion functions F 0 and F1 can be derived.
1.2
Co-ordinate system, running coordinate s
1.2.1
A 2-D cartesian co-ordinate system is to be used. The choice of the reference point O (origin of co-ordinate
system) is free, but for symmetric cross sections it is advantageous to define the origin at the line of symmetry of thecross section. The running co-ordinate s starts within symmetric cross sections at the intersection of the line ofsymmetry with the cross section geometry, e.g. in hull cross sections at the intersection of centreline and bottom shellor double-bottom as indicated by 0 in Fig. 2 to Fig. 4. The orientation of s as well as the direction of integration－285－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Appendix 1)

within closed cells is to be considered with respect to the algebraic signs and the assembly of the system of equations
for the torsion function.
1.3
1.3.1

Computation of several properties for each part of the cross section

wi = w k of the preceding partial area or of the preceding point of bifurcation. (to be set equal to zero at the
wk

beginning of the computation)ll= wi + y i z k - y k z i - F i , with F i
ti
ti
=

l

( yk - yi ) 2 + ( z k - z i ) 2

=

lt

Sy =

A

Sz =

A

Sw =

A

Iy =

A

A

=

Iz

Summation
åA2(z i + z k )2(yi + yk )2

(wi + wk )z(z + z z + z )A (y + y y + y )
3
3

2
i

2
i

i

2
k

k

i

k

6

[(2 y k + y i )z k + (2 y i + y k )z i ]3(w + w w + w )

Iw =

A

I wy =[(2 y k + y i )wk + (2 y i + y k )wi ]A [(2 z k + z i )w k + (2 z i + z k )wi ]
6

st =

A

2
i

i

y

2
k

A

3

åS
åS
å Sw
åI
åI
åI
å Iw
å Iw
å Iw
å s t3y

I yz =

I wz =

within closed cells

k

y

yz

2
k

6

lt

y

z

3

－286－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Appendix 1)

1.4

Computation of cross sectional properties for the entire cross section
Symmetric cross section

Asymmetric cross section:

A

=

ys

=

zs

=

Iy

=

Iz

=

I yz

=

IT

=

åA
åS
åA
åS
åA
åI - å Az
åI - åA yåI - å A y z(only half of the section is modeled)

z

y

=

I wy

=

I wz

=

yM

=

zM

=

Iw

=

=

ys

=

zs

=

åA
åS
åA
åS
åA
2(å I - å A z )

2

z

y

y

2
s

Iy

=

z

2
s

Iz

=

2 å I z - å A y s2

(

)

yz

s

IT

=

é
2ê
ê
ë

ù
st3
+
2 A yi F i ú
3 Cell i
ú
û

I wy

=

2

zM

=

-

Iw

=

2å I w + z M I wyst

å 3 + å (2 A F )
yi

2
s

y

s

3

i

Cell i

w0

A

å Sw
åA
å Iw - å A y w
å Iw - å A z w
y

s

0

z

s

0

å

å(

)

å Iw

y

I wz I z - I wy I yz
I y I z - I 2yz
I wz I yz - I wy I y
I y I z - I 2yz

å Iw - å Aw + z Iw - y Iw
2
0

M

y

M

z

I wy
Iz

I y , I z , I yz are to be computed with relation to the centre of gravity.
S x , S y , S w , I w , I wy and I wz are to be computed with relation to shear centre M

The sector-coordinate w has to be transformed with respect to the location of the shear centre M. For crosssections of type A, w0 is to be added to each wi and w k as defined in 1.3
For cross sections of type B and C, Dw can be calculated as follows:
D wi = z M yi
where:
wO: Calculated sector co-ordinate with respect to the centre of the coordinate system (O) selected forthe calculation according to the formulae for w k given in 1.3

w: Transformed sector co-ordinate with respect to shear centre M
y M , z M : Distance between shear centre M and centre of the coordinate system B.
The transformed values of w can be obtained by adding Dw to the values of wO obtained according to theformulae in 1.3.
The transformed value for w is to be equal to zero at intersections of the cross section with the line ofsymmetry (centreline for ship-sections).

－287－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Appendix 1)

Fig. 2

Cross sections of type A
2
1
0
4
3

z
1

3

2

z

5

y

4
y

0

Fig. 3

5

Cross sections of type B
8

z

z
y
1

4

0

Fig. 4

6

y

2

symm.

symm.

7

9

3

4

5

2

0 1

Cross section of type C
6

5

z
y

3

4

7

3

symm.

2
0

1

Main Line
1. Byline
2. Byline

Designation of line types (numbers at particular parts of cross sections) gives the order of the particular parts forthe calculation and therefore the direction of the running coordinate s.

－288－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Appendix 1)

2.

Example calculation for a single side hull cross section

2.1
Cross section data
2.1.1
The cross section is shown in Fig. 5. The co-ordinates of the node-points marked by filled black circles in Fig. 5
are given in the Table 1, where the plate thicknesses and the line segments (marked by circles in Fig. 5) of the crosssection are given in Table 2.
Table 1
Node

Node-coordinates of cross-section
Y Coordinate

Z Coordinate

0

0.00

0.00

1

14.42

0.00

2

16.13

1.72

3

16.13

6.11

4

11.70

1.68

number

5

0.00

1.68

6

16.13

14.15

7

16.13

19.6

8

7.50

20.25

9

7.50

19.63

10

0.00

20.25

2.2
Determination of the torsion function
2.2.1
The first step is to build a linear system of equation for the determination of the torsion function
cell. The cross section and the cells are shown in Fig. 5.
Fig. 5of each closed

Single side hull cross section
8

11
10

Cell 398

9

7

Cell 2

F3

7

F2

10

6

Cell 1

F1

6

3
4

Z
Y

5

5

4

Cell 4
0

－289－

3
2

F4
S

1

2
1

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Appendix 1)

Table 2Dimensions and nodes of line segments of the cross section

Line-No.

Node i

Node k

yi

zi

yk

zk

LengthThickness

1

0

1

0.00

0.00

14.42

0.00

14.42

0.017

2

1

2

14.42

0.00

16.13

1.72

2.43

0.017

3

2

3

16.13

1.72

16.13

6.11

4.39

0.018

4

3

4

16.13

6.11

11.70

1.68

6.26

0.019

5

4

5

11.70

1.68

0.00

1.68

11.70

0.021

6

3

6

16.13

6.11

16.13

14.15

8.04

0.018

7

6

7

16.13

14.15

16.13

19.6

5.45

0.021

8

7

8

16.13

19.60

7.50

20.25

8.65

0.024

9

8

9

7.50

20.25

7.50

19.63

0.62

0.024

10

9

6

7.50

19.63

16.13

14.15

10.22

0.015

11

8

10

7.50

20.25

0.00

20.25

7.50

0.012

Under consideration of the 4 cells (marked by rectangles in Fig. 5) of the cross section, the following systemof equation for the determination of the torsion function can be developed. It should be noted that thedirection of the rotation is to be considered (the rotation directions for the torsion functions i should point in
the same direction for all i to build up the system of equations).
ssss
F 2 - å F 3 - å F 4 = 2å A
å1 t F1 - å
1- 2 t1- 3 t1- 4 t1ss- å F1 + å F 2= 2å A1- 2 t2 t
2ss- å F1+ å F3= 2å A
1- 3 t3 t
3ss- å F1+ å F 4 = 2å A
1- 4 t4 t
4The coefficients of the matrix can be calculated as follows:s 2 11700 2 6265 2 8040 2 10223 2 620 2 7500
å1 t = 21 + 19 + 18 + 15 + 24 + 12 = 5331.81
s 10223 5450 620 8654
å2 t = 15 + 21 + 24 + 24 = 1327.48så3 t = 1327.48
s 2 14420 2 11700 2 6265 2 2425 2 4390
å4 t = 17 + 21 + 19 + 17 + 18 = 4243.34
s 10223 620=+= 707.36
å
15
24
1- 2 ts= 707.36
å
1- 3 ts 2 11700 2 6265
= 1773.76
=
+
å
21
19
1- 4 t
The areas of the cells can be calculated as follows:2å A = 2 2 260.72 = 1042.90 m 2
1

2å A = 2 26.19 = 52.38 m 2
2

2å A = 52.38 m 2
3

2å A = 2 2 35.44 = 141.76 m 2
4

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 8 Appendix 1)

With these results the coefficient matrix will become:
5331.81F1-707.360F 2 -707.36F 3-1773.76F 4- 707.36F 1 + 1327.48F 2- 707.36F 1- 1773.76F 1+ 1327.48F 3+ 4243.34F 4= 1042.90= 52.38= 52.38= 141.76

The solution of this system gives:
F 1 = 0.3018

F 2 = 0.2003
F 3 = 0.2003
F 4 = 0.1596
2.3
Determination of the line-segment properties
2.3.1
The next step is the determination of k according to the formulae given in 1.3. s starts at point 0 (Fig. 5) withæ l i ö isi = 0 and follows the path from point 0 to point 1, 2, 3, 4 up to point 5. It is to be noted, that the term F çè ti ølö where for the line segments 4 andfor the line segments 1 to 3 (between points 0 and 3) calculated as F 4 æç 1K3
t1K3 ø
èlö because line segments 4 and 5 are shared walls of cell 4 and cell 1. The
5 this term becomes (F 4 - F1 ) æç 4K5
t 4K5 øè
rotation direction for the torsion functions together with the direction of integration (direction of path, which one
follows for the calculation) determines the algebraic sign within this term.
For the line segment 6 i has to be set to the value at point 3 and F æç l i ö = F 1 æç l 6 ö . s follows now the pathè ti ø
è t6 ø
from point 6 to point 7, 8, 9 back to point 6. The shared wall between cell 2 and cell 1 has to be considered for theterms which include the torsion function . For the line segment 11 between point 8 and 10, i has to be set to thevalue at point 8.
The other properties of the line segments can be calculated by the formulas given in 1.3.
2.4
Determination of cross-section properties
2.4.1
After the summation of the line-segment properties, the cross section properties can be calculated as described in
1.4.
The sector coordinate has to be transformed with respect to the shear centre as described in 1.4.
The result of the calculations gives the sector co-ordinates, as indicated in Table 3.
Table 3

Sector co-ordinates for the cross section of Fig 5

Point i

O, i

i

i

0

0.00

0.00

0.00

1

-135.9784.99-50.982-134.04

95.07-38.97

3-102.32

95.07

-7.25

4

-99.4968.96-30.53

5

-0.06

0.00

-0.06

6

-108.20

95.07-13.13

7-72.30

95.07

22.77

8

35.07

44.21

79.27

9

33.08

44.21

77.28

10

-2.75

0.00

-2.75

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2.5
Notes
2.5.1
For holds of single side skin construction, the hull cross section normally can be simplified in a section with fourboxes (cell 1 cargo hold, cell 2 and 3 wing tanks and cell 4 hopper tanks and double bottom as shown in thecalculation example) whereas the cross section of holds of double side skin construction can be simplified to a crosssection with two closed cells only (cell 1 cargo hold, cell 2 double hull). For the plate thickness of the line elementswith variable thicknesses an equivalent plate thickness can be used calculated by the following formulae:
t l + t l + K + ti l i + K + t k l kteq = 1 1 2 2
k
å li
i =1

Due to the simplifications, the value of the sector co-ordinate can differ from 0 at the intersections between the
cross section and centreline. The difference between the value of the sector co-ordinate and the value of thetorsional moment of inertia IT for the simplified cross section is in normal cases less than 3% compared to the valuesof the original cross section.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 1)

Chapter 9

OTHER STRUCTURES

Section 1

FORE PART

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
L2 : Rule length LCSR-B, but to be taken not greater than 300 m
TB : Minimum ballast draught, in m, for normal ballast conditions
k : Material factor, defined in Ch 3, Sec 1, 2.2
m : Coefficient taken equal to:m = 10 for vertical stiffeners, vertical primary supporting members
m = 12 for other stiffeners, other primary supporting members
ta : Allowable shear stress, in N/mm2, taken equal to:Rta = Y3s : Spacing, in m, of ordinary stiffeners or primary supporting members, measured at mid-span along the chordl : Span, in m, of ordinary stiffeners or primary supporting members, measured along the chord between the
supporting members, see Ch 3, Sec 6, 4.2 or 5.3 respectively
ca : Aspect ratio of the plate panel, equal to:2sæsöc a = 1.21 1 + 0.33ç
- 0.69 , to be taken not greater than 1.0llè ø

cr : Coefficient of curvature of the panel, equal to:sc r = 1- 0.5 , to be taken not less than 0.4
r
r : Radius of curvature, in m.

1.

General1.1
Application
1.1.1
The requirement of this Section apply to:・ the structures located forward of the collision bulkhead, i.e.:・ the fore peak structures
・ the stem・ the reinforcements of the bow flare area, according to 4.1
・ the reinforcements of the flat bottom forward area, according to 5.1.
1.1.2
Fore part structures which form the boundary of spaces not intended to carry liquids, and which do not belong to theouter shell, are to be subjected to lateral pressure in flooding conditions. Their scantlings are to be determinedaccording to the relevant criteria in Ch 6.
1.2
Net thicknesses
1.2.1
As specified in Ch 3, Sec 2, all thicknesses referred to in this Section are net, i.e. they do not include any corrosion
addition. The gross thicknesses are to be obtained as specified in Ch 3, Sec 2, 3.

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2.

Arrangement

2.1
Structural arrangement principles
2.1.1 General
Scantlings of the shell envelope, upper deck and inner bottom, if any, may be tapered towards the forward end.
Special consideration is to be paid to the structural continuity of major longitudinal members in order to avoid abruptchanges in section.
Structures within the fore peak, such as platforms, decks, horizontal ring frames or side stringers are to be scarphed
into the structure aft into the cargo hold.
Where inner hull structures terminate at the collision bulkhead, the structural continuity is to be ensured forward of
the collision bulkhead by adequate structure with tapering brackets.
Longitudinal stiffeners of deck, bottom and side shell are to be extended as far forward as practicable.
All shell frames and tank boundary stiffeners are to be continuous, or are to be bracketed tat their ends.
Where the brackets are provided to ensure the structural continuity from the forward end to 0.15LCSR-B behind fore
perpendicular, flanged brackets have to be used.
2.1.2 Structures in tanks
Where peaks are used as tanks, stringer plates are to be flanged or face bars are to be fitted at their inner edges.
Stringers are to be effectively fitted to the collision bulkhead so that the forces can be properly transmitted.
2.2
Tripping brackets
2.2.1
For peaks or other tanks forward of the collision bulkhead transversely framed, tripping brackets vertically spaced
not more than 2.6 m are to be fitted, according to Fig. 1, between primary supporting members, decks and/or platforms.
The as-built thickness of the tripping brackets is to be not less than the as-built thickness of the side frame webs towhich they are connected.
Fig. 1

Tripping brackets

2.3
Floors and bottom girders
2.3.1
Where no centreline bulkhead is provided, a centre bottom girder is to be fitted.
In general, the minimum depth of the floor at the centerline and center girders is to be not less than the required depthof the double bottom of the foremost cargo hold.
2.3.2 Solid floors
In case of transverse framing, solid floors are to be fitted at every frame.
In case of the longitudinal framing, the spacing of solid floors is not to be greater than 3.5 m or four transverse frame
spaces, whichever is the smaller. Larger spacing of solid floors may be accepted, provided that the structure is verified
by means of FEA deemed appropriate by the Society.
2.3.3 Bottom girders
In case of transverse framing, the spacing of bottom girders is not to exceed 2.5 m.
In case of longitudinal framing, the spacing of bottom girders is not to exceed 3.5 m.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 1)

Larger spacing of solid floors may be accepted, provided that the structure is verified by means of FEA deemed
appropriate by the Society.
3.

Load model

3.1
Load point
3.1.1
Unless otherwise specified, lateral pressure is to be calculated at load points according to:・ Ch 6, Sec 1, 1.5, for plating
・ Ch 6, Sec 2, 1.4, for stiffeners.
3.2
Pressure in bow area
3.2.1 Lateral pressure in intact conditions
The pressure in bow area, in kN/m2, is to be taken equal to:(pS+ pW)
where:
pS, pW : Hydrostatic and hydrodynamic pressures, according to Ch 4, Sec 5, or internal still water and inertialpressures according to Ch 4, Sec 6, 2, to be considered among load cases H, F, R and P..
3.2.2 Lateral pressure in testing conditions
The lateral pressure pT in testing conditions is taken equal to:
・ pT = pST - pS
for bottom shell plating and side shell plating
・ pT = pST
otherwise,
where:
pST : Testing pressure defined in Ch 4, Sec 6, 4
pS : Pressure taken equal to:・ if the testing is carried out afloat: hydrostatic pressure defined in Ch 4, Sec 5, 1 for the draught T1,
defined by the Designer, at which the testing is carried out. If T1 is not defined, the testing is
considered as being not carried out afloat
・ if the testing is not carried out afloat: pS = 0
3.2.3 Elements of the outer shell
The still water and wave lateral pressures are to be calculated considering separately:・ the still water and wave external sea pressures・ the still water and wave internal pressure considering the compartment adjacent to the outer shell as being loaded.
If the compartment adjacent to the outer shell is intended to carry liquids, this still water and wave internalpressures are to be reduced from the corresponding still water and wave external sea pressures.
3.2.4 Elements other than those of the outer shell
The still water and wave lateral pressures to be considered as acting on an element which separates two adjacentcompartments are those obtained considering the two compartments individually loaded.
3.3
Bow flare area pressure
3.3.1
The bow pressure p FB , in kN/m2, is to be obtained according to Ch 4, Sec 5, 4.1.
3.4
Bottom slamming pressure
3.4.1
The bottom slamming pressure p SL , in kN/m2, in the flat bottom forward is to be obtained according to Ch 4, Sec 5,
4.2.
4.

Scantlings

4.1
Bow flare reinforcement
4.1.1
The bow flare area to be reinforced is that extending forward of 0.9LCSR-B from the aft end and above the normal
ballast waterline according to the applicable requirements in 4.2 to 4.4.

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4.2
Plating
4.2.1
The net thickness of plating are to be not less than those obtained from the formulae in Table 1 and Table 2.
Table 1

Net minimum thickness of plating
Minimum net thickness, in mm

Bottom,5.5 + 0.03LCSR-B

Side

0.85LCSR-B 1/2

Inner bottom

5.5 + 0.03LCSR-B

Strength deck

4.5 + 0.02LCSR-B

Platform and wash bulkhead

6.5

Transverse and longitudinal

0.6 LCSR-B1/2

watertight bulkheads

Table 2

Net thickness of plating
Net thickness, in mm

Intact conditions

t = 15.8ca cr s

pS + pW
0.9 RYBow flare areat = 15.8ca cr s

pFB
0.9 RY

Testing conditions

t = 15.8cacr s

pT
1.05 RY

4.3
Ordinary stiffeners
4.3.1 General
The requirements of this sub-article apply to ordinary stiffeners considered as clamped at both ends. For otherboundary conditions, the yielding check is to be considered on a case by case basis.
4.3.2
The net dimensions of ordinary stiffeners are to comply with the requirements in Ch 6, Sec 2, 2.3
4.3.3
The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:・ t = 3.0 + 0.015L2
・ 40% of the net required thickness of the attached plating, to be determined according to 4.2 and 5.2.
The net dimensions of ordinary stiffeners are to comply with the requirement in Ch 6, Sec 2, 2.2.2 and 2.3.
4.3.4
The net scantlings of single-span ordinary stiffeners are to be not less than those obtained from the formulae in Table
3.

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Table 3

Net scantlings of single span ordinary stiffeners
Net section modulus w, in cm3

Stiffener type
Single span ordinary stiffeners subjected tolateral pressure
Single span ordinary stiffeners located in bow
flare area
Single span ordinary stiffeners subjected totesting pressure( p S + pW )sl 10 3

Net sectional shear area Ash,in cm22w=

0.9mRYw=
w=

pFB sl 2 3
100.9mRYp T sl 2
10 3
1.05mRYAsh =5( p S + pW )sl
t a sin f

Ash =
Ash =

5 p FB sl
t a sin f

5 p T sl
1.05t a sin fwhere:

f : Angle, in deg, between the stiffener web and the shell plate, measured at the middle of the stiffener span;
the correction is to be applied when f is less than 75.

4.3.5
The maximum normal stress s and shear stress t in a multi-span ordinary stiffener are to comply with the formulae in
Table 4.
The maximum normal stress s and shear stress t in a multi-span ordinary stiffener are to be determined by a direct
calculation taking into account:・ the distribution of still water and wave pressure and forces, if any
・ the number and position of intermediate supports (decks, girders, etc.)
・ the condition of fixity at the ends of the stiffener and at intermediate supports
・ the geometrical characteristics of the stiffener on the intermediate spans.
Table 4Checking criteria for multi-span ordinary stiffeners
Condition

IntactTesting

Normal stresss £ 0.9 RYs £ 1.05RY

Shear stresst £ tat £ 1.05t a

4.4
Primary supporting members
4.4.1 Minimum thickness
The net thickness of the web of primary supporting members, in mm, is to be not less than that obtained from thefollowing formula:t = 0 .7 L 2

4.4.2 Side transverses
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of side transverses are to be not lessthan the values obtained from the following formulae:( p + pW )sl 2 3
10
w= S
0.9mRY5( p S + pW )sl
Ash =t a sin f
In addition, the net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of side transverses locatedwithin the bow flare area are to be not less than the values obtained from the following formulae:
p sl 2 3
10
w = FB
0.9mRY
5 p FB sl
Ash =t a sin f
4.4.3 Side girders
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of side girders are to be not less thanthe values obtained from the following formulae:－297－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 1)w=( p S + pW )sl 2
0.9mRY

Ash =

10 3

5( p S + pW )sl
t a sin f

In addition, the net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of side girders locatedwithin the bow flare area are to be not less than the values obtained from the following formulae:
p sl 2 3
10
w = FB
0.9mRY
5 p FB sl
Ash =t a sin f
4.4.4 Deck primary supporting members
The net scantlings of deck primary supporting members are to be not less than those obtained from the formulae in
Table 5. The design pressures in the formulae are taken from intact conditions and testing conditions respectively asstated in 3.2. For a complex deck structure, a calculation deemed appropriate by the Society may be carried out in lieu
of the formulae.
Table 5 Net scantlings of deck primary supporting members
Condition
Primary supporting members subjected tolateral pressure in intact conditions

Net section modulus w, in cm3w=

Primary supporting members subjected tolateral pressure in testing conditions

Net sectional shear area Ash, in cm25( pS + pW )sl
t a sin f( pS + pW )sl 2 103

Ash =pT sl 2103
1.05mRY

Ash =0.9mRYw=

5 pT sl
1.05t a sin fwhere:

f : Angle, in deg, between the primary supporting member s web and the shell plate, measured at the middle of the
primary supporting member s span; the correction is to be applied when f is less than 75.

5.

Strengthening of bottom forward area

5.1
5.1.1

Application

The bottom forward area to be reinforced is the part of the ship's bottom extending forward of 0.2V LCSR- B from thefore perpendicular end, up to a height of 0.05TB or 0.3 m above base line, whichever is the smaller.
5.2
Bottom plating
5.2.1
The net thickness, in mm, of the bottom forward area, is not to be less than:t = 15.8C a C r s

C s p SL
ReH

where:
Cs : Coefficient relating to load patch of impact pressure, taken equal to:
Cs = 1.0
where no intermediate longitudinals is provided between ordinary stiffeners
where intermediate longitudinals are provided between ordinary stiffeners.
Cs = 1.3
5.2.2
For ships with a rise of floor the strengthened plating must at least extend to the bilge curvature.
5.3
Ordinary stiffeners
5.3.1
The net section modulus, in cm3, of transverse or longitudinal ordinary stiffeners of the bottom forward area is not tobe less than:－298－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 1)w=

C s p SL sl 2 3
10
16 ReH

where:
Cs : Coefficient defined in 5.2.1.
5.3.2
The net shear area, in cm2, of transverse or longitudinal ordinary stiffeners of the bottom forward area is not to be less
than:
A=

5 3 p SL s(l - 0.5s )R eH sin f

The area of the welded connection has to be at least twice this value.
5.4
Primary supporting members
5.4.1 Girders
The net thickness of girders in double bottom forward area, in mm, is not to be less than the greatest of either of thevalue t1 to t3 specified in the followings according to each location:c A p SL Sl
t1 =2(d 0 - d1 )t a
t2 = 1.75 3t3 =H 2 a 2t a
t1
¢
C1

C1¢¢a
k

where:
cA : Coefficient taken equal to:cA = 3/A, with 0.3 £ c A £ 1.0: Loaded area, in m2, between the supports of the structure considered, obtained from the following
formula:A=Sl
pSL : As defined in 3.4
S : Spacing of centre or side girders under consideration, in ml : Span of centre or side girders between floors under consideration, in m
d0 : Depth of the centre or side girder under consideration, in m
d1 : Depth of the opening, if any, at the point under consideration, in m
H : Value obtained from the following formulae:f(a) Where the girder is provided with an unreinforced opening : H = 1 + 0.5a(b) In other cases: H = 1.0
f : Major diameter of the openings, in m
a : The greater of a or S1 , in m.
Aa: Depth of girders at the point under consideration, in m, Where, however, if horizontal stiffeners are fitted
on the girder, a is the distance from the horizontal stiffener under consideration to the bottom shell
plating or inner bottom plating, or the distance between the horizontal stiffeners under consideration
S1 : Spacing, in m, of vertical ordinary stiffeners or floors
C1¢ : Coefficient obtained from Table 6 depending on S1 / a . For intermediate values of S1 / a , C1¢ is to be
determined by linear interpolation.
C1¢¢ : Coefficient obtained from Table 7 depending on S1 / a . For intermediate values of S1 / a , C1¢¢ is to beobtained by linear interpolation.

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Coefficient C1¢

Table 6S1a
C1¢

0.3 and under

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

1.4 and over

64

38

25

19

15

12

10

9

8

7

Coefficient C1¢¢

Table 7S1a

C1¢¢

0.3 and
under

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

1.4

1.6 andoverCentre girder

4.4

5.4

6.3

7.1

7.7

8.2

8.6

8.9

9.3

9.6

9.7

Side girder

3.6

4.4

5.1

5.8

6.3

6.7

7.0

7.3

7.6

7.9

8.0

5.4.2 Floors
The net thickness of floors in double bottom forward area, in mm, is not to be less than the greatest of either of thevalue t1 to t3 specified in the followings according to each location:c A pSL Sl
t1 =2(d 0 - d1 )t a
t2 = 1.75 3t3 =H 2 a 2t a
t1
C2¢

8.5S 2kwhere :
cA : Coefficient taken equal to:cA = 3/A, with 0.3 £ c A £ 1.0: Loaded area, in m2, between the supports of the structure considered, obtained from the following
formula:A=Sl
pSL : As defined in 3.4
S : Spacing of solid floors under consideration, in ml : Span of floors between centre girder and side girder or side girders under consideration, in m
d 0 : Depth of the solid floor at the point under consideration in m
d1 : Depth of the opening, if any, at the point under consideration in m
A

H : Value obtained from the following formulae:a) Where openings with reinforcement or no opening are provided on solid floors:
1) Where slots without reinforcement are provided:

H = 4 .0b)d2
- 1.0 , without being taken less than 1.0
S12) Where slots with reinforcement are provided: H = 1.0
Where openings without reinforcement are provided on solid floors:
1) Where slots without reinforcement are provided:
æ
f
d
f ö
H = çç1 + 0.5
4.0 2 - 1.0 , without being taken less than 1 + 0.5
d
d
S
0 ø
1
0
è
2)

Where slots with reinforcement are provided:f
H = 1 + 0 .5
d0

d 2 : Depth of slots without reinforcement provided at the upper and lower parts of solid floors, in m,

whichever is greater
S1 : Spacing, in m, of vertical ordinary stiffeners or girders
f : Major diameter of the openings, in m.

－300－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 1)a: Depth of the solid floor at the point under consideration, in m, Where, however, if horizontal stiffeners
are fitted on the floor, a is the distance from the horizontal stiffener under consideration to the bottom
shell plating or the inner bottom plating or the distance between the horizontal stiffeners underconsideration
S 2 : The smaller of S1 or a , in m
C2¢ : Coefficient given in Table 8 depending on S1 / d 0 . For intermediate values of S1 / d 0 , C2¢ is to be
determined by linear interpolation.
Coefficient C2¢Table 8
S1 / d 0
C 2¢

6.

0.3
and under
64

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.2

38

25

19

15

12

10

9

8

1.4
and over
7

Stem

6.1
Bar stem
6.1.1
The gross cross sectional area, in cm2, of a bar stem below the load waterline is not to be less than:Ab = 1.25LCSR-B
6.1.2
Starting from the load waterline, the cross sectional area of the bar stem may be reduced towards the upper end to
0.75Ab.
6.2
Plate stem and bulbous bows
6.2.1
The gross thickness, in mm, is not to be less than the values obtained from the following formula:t = (0.6 + 0.4 sB )(0.08LCSR - B + 6 ) k , without being taken greater than 22 k

where:
sB : Spacing, in m, between horizontal stringers (partial or not), breasthooks, or equivalent horizontal
stiffening members.
The gross plate thickness is to be not less than the net thickness, obtained according to 4.2, plus the corrosion
addition tC as defined in Ch 3, Sec 3.
Scantlings of the ordinary stiffeners are to be determined according to 4.3.
6.2.2
Starting from 0.6 m above the load waterline up to T+ C, the gross thickness may gradually be reduced to 0.8t, wheret is the gross thickness defined in 6.2.1.
6.2.3
Plate stems and bulbous bows must be stiffened by breasthooks and/or frames.
7.

Forecastle

7.1
General
7.1.1
An enclosed forecastle is to be fitted on the freeboard deck.
The aft bulkhead of the enclosed forecastle is to be fitted in way or aft of the forward bulkhead of the foremost hold,as shown in Fig. 2.
However, if this requirement hinders hatch cover operation, the aft bulkhead of forecastle may be fitted forward of
the forward bulkhead of the foremost cargo hold provided the forecastle length is not less than 7% of ship length forfreeboard as specified in Ch 1, Sec 4, 3.2 abaft the fore side of stem.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 1)

Fig. 2

Forecastle

7.1.2
The forecastle height HF above the main deck is to be not less than the greater of the following values:
・ the standard height of a superstructure as specified in Ch 1, Sec 4, 3.18
・ HC + 0.5 m, where HC is the height of the forward transverse hatch coaming of the foremost cargo hold, i.e. cargohold No.1.
7.1.3
All points of the aft edge of the forecastle deck are to be located at a distance less than or equal to lF:
l F = 5 H F - HCfrom the hatch coaming plate in order to apply the reduced loading to the No.1 forward transverse hatch coaming andNo.1 hatch cover in applying Ch 9, Sec 5, 6.2.2 and Ch 9, Sec 5, 7.3.8.
7.1.4
A breakwater is not to be fitted on the forecastle deck with the purpose of protecting the hatch coaming or hatch
covers. If fitted for other purposes, it is to be located such that its upper edge at centreline is not less than HB/tan20
forward of the aft edge of the forecastle deck, where HB is the height of the breakwater above the forecastle (see Fig. 2).

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 2)

Section 2

AFT PART

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
L1 : Rule length LCSR-B, but to be taken not greater than 200 m
L2 : Rule length LCSR-B, but to be taken not greater than 300 mk: Material factor, defined in Ch 3, Sec 1, 2.2
zTOP : Z co-ordinate, in m, of the top of the tankm : Coefficient taken equal to:m = 10for vertical stiffeners, vertical primary supporting members
m = 12for other stiffeners, other primary supporting members
ta : Allowable shear stress, in N/mm2, taken equal to:Rta = Y3s: Spacing, in m, of ordinary stiffeners or primary supporting members, measured at mid-span along the chordl: Span, in m, of ordinary stiffeners or primary supporting members, measured along the chord between the
supporting members, see Ch 3, Sec 6, 4.2 or 5.3 respectively
ca : Aspect ratio of the plate panel, equal to:2sæsöc a = 1.21 1 + 0.33ç
- 0.69 , to be taken not greater than 1.0
l
l
è ø

cr

r

1.

: Coefficient of curvature of the panel, equal to:sc r = 1- 0.5 , to be taken not less than 0.4
r: Radius of curvature, in m.

General1.1
Introduction
1.1.1
The requirements of this Section apply for the scantlings of structures located aft of the aft peak bulkhead and for thereinforcements of the flat bottom aft area.
1.1.2
Aft peak structures which form the boundary of spaces not intended to carry liquids, and which do not belong to theouter shell, are to be subjected to lateral pressure in flooding conditions. Their scantlings are to be determinedaccording to the relevant criteria in Ch 6.
1.2
Connections of the aft part with structures located fore of the aft peak bulkhead
1.2.1 Tapering
Adequate tapering is to be ensured between the scantlings in the aft part and those fore of the aft peak bulkhead. The
tapering is to be such that the scantling requirements for both areas are fulfilled.
1.3
Net scantlings
1.3.1
As specified in Ch 3, Sec 2, all thicknesses referred to in this Section are net, i.e. they do not include any corrosion
addition. The gross thicknesses are to be obtained as specified in Ch 3, Sec 2, 3.

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2.

Load model

2.1
Load point
2.1.1
Unless otherwise specified, lateral pressure is to be calculated at load points according to:・ Ch 6, Sec 1, 1.5, for plating
・ Ch 6, Sec 2, 1.4, for stiffeners.
2.2
Lateral pressures
2.2.1 Lateral pressure in intact conditions
The aft part lateral pressure in intact conditions, in kN/m2, is to be taken equal to:(pS + pW)
where:
pS, pW : Hydrostatic and hydrodynamic pressures according to Ch 4, Sec 5, or internal still water and inertialpressures according to Ch 4, Sec 6, 2, to be considered among load cases H, F, R and P.
2.2.2 Lateral pressure in testing conditions
The lateral pressure pT in testing conditions is taken equal to:
・ pT = pST - pS
for bottom shell plating and side shell plating
・ pT = pST
otherwise,
where:
pST : Testing pressure defined in Ch 4, Sec 6, 4
pS : Pressure taken equal to:・ if the testing is carried out afloat: hydrostatic pressure defined in Ch 4, Sec 5, 1 for the draught T1,
defined by the Designer, at which the testing is carried out. If T1 is not defined, the testing is
considered as being not carried out afloat
・ if the testing is not carried out afloat: pS = 0
2.2.3 Elements of the outer shell
The still water and wave lateral pressures are to be calculated considering separately:・ the still water and wave external sea pressures・ the still water and wave internal pressure considering the compartment adjacent to the outer shell as being loaded.
If the compartment adjacent to the outer shell is intended to carry liquids, this still water and wave internalpressures are to be reduced from the corresponding still water and wave external sea pressures.
2.2.4 Elements other than those of the outer shell
The still water and wave lateral pressures to be considered as acting on an element which separates two adjacentcompartments are those obtained considering the two compartments individually loaded.
3.

Aft peak

3.1
Arrangement
3.1.1 General
The aft peak is, in general, to be transversely framed.
3.1.2 Floors
Solid floors are to be fitted at every frame spacing.
The floor height is to be adequate in relation to the shape of the hull. Where a sterntube is fitted, the floor height is toextend at least above the sterntube. Where the hull lines do not allow such extension, plates of suitable height withupper and lower edges stiffened and securely fastened to the frames are to be fitted above the sterntube.
In way of and near the rudder post, propeller post and rudder horn, floors are to be extended up to the peak tank top
and are to be increased in thickness; the increase will be considered by the Society on a case by case basis, depending on
the arrangement proposed.
Floors are to be provided with stiffeners located at intervals not exceeding 800 mm.
3.1.3 Side framesSide frames are to be extended up to a deck located above the full load waterline.

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Side frames are to be supported by one of the following types of structure:・ non-tight platforms, to be fitted with openings having a total area not less than 10% of the area of the platforms
・ side girders supported by side primary supporting members connected to deck transverses.
3.1.4 Platforms and side girders
Platforms and side girders within the peak are to be arranged in line with those located in the area immediately
forward.
Where this arrangement is not possible due to the shape of the hull and access needs, structural continuity between
the peak and the structures of the area immediately forward is to be ensured by adopting wide tapering brackets.
Where the aft peak is adjacent to a machinery space whose side is longitudinally framed, the side girders in the aftpeak are to be fitted with tapering brackets.
3.1.5 Longitudinal bulkheads
A longitudinal non-tight bulkhead is to be fitted on the centreline of the ship, in general in the upper part of the peak,and stiffened at each frame spacing.
Where either the stern overhang is very large or the maximum breadth of the space divided by watertight and wash
bulkheads is greater than 20 m, additional longitudinal wash bulkheads may be required.
4.

Scantlings

4.1
Plating
4.1.1
The net thickness of plating are to be not less than those obtained from the formulae in Table 1 and Table 2.
Table 1

Net minimum thickness of plating
Minimum net thickness, in mm

Bottom

5.5 + 0.03LCSR-B
0.85LCSR-B1/2

Side and transom
Inner bottom

5.5 + 0.03LCSR-B

Strength deck

4.5 + 0.02LCSR-B

Platform and wash bulkhead

6.5

Transverse and longitudinalwatertight bulkheads

0.6 LCSR-B1/2

Table 2

Net thickness of plating
Net thickness, in mm

Intact conditions

t = 15.8c a c r s

p S + pW
0.9 RY

Testing conditions

t = 15.8c a c r s

pT
1.05RY

4.2
Ordinary stiffeners
4.2.1 General
The requirements of this sub-article apply to ordinary stiffeners considered as clamped at both ends. For otherboundary conditions, the yielding check is to be considered on a case by case basis.
4.2.2
The net dimensions of ordinary stiffeners are to comply with the requirements in Ch 6, Sec 2, 2.3.
4.2.3
The net thickness of the web of ordinary stiffeners, in mm, is to be not less than the greater of:・ t = 3.0 + 0.015L2
・ 40% of the net required thickness of the attached plating, to be determined according to 4.1.
The net dimensions of ordinary stiffeners are to comply with the requirement in Ch 6, Sec 2, 2.2.2 and 2.3.

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4.2.4
The net scantlings of single-span ordinary stiffeners are to be not less than those obtained from the formulae in Table
3.
Table 3
Net scantlings of single span ordinary stiffeners
Net section modulus w, in cm3

Stiffener type
Single span ordinary stiffeners subjected tolateral pressure
Single span ordinary stiffeners subjected totesting pressurew=

Net sectional shear area Ash,in cm25( p S + pW )sl
t a sin f( p S + pW )sl 2 10 3Ash =p T sl 2
10 3
1.05mRY

Ash =w=

0.9mRY

5 p T sl
1.05t a sin fwhere:

f : Angle, in deg, between the stiffener web and the shell plate, measured at the middle of the stiffener span; thecorrection is to be applied when f is less than 75.

4.2.5
The maximum normal stress s and shear stress t in a multi-span ordinary stiffener are to comply with the formulae in
Table 4.
The maximum normal stress s and shear stress t in a multi-span ordinary stiffener are to be determined by a direct
calculation taking into account:・ the distribution of still water and wave pressure and forces, if any
・ the number and position of intermediate supports (decks, girders, etc.)
・ the condition of fixity at the ends of the stiffener and at intermediate supports
・ the geometrical characteristics of the stiffener on the intermediate spans.
Table 4Checking criteria for multi-span ordinary stiffeners
Condition

IntactTesting

Normal stresss £ 0.9 RYs £ 1.05RY

Shear stresst £ tat £ 1.05t a

4.3
Primary supporting members
4.3.1 Floors
The net thickness of floors is to be not less than that obtained, in mm, from the following formula:t = 0 .7 L 2

4.3.2 Side transverses
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of side transverses are to be not lessthan the values obtained from the following formulae:( p + pW )sl 2 3
10
w= S
0.9mRY5( p S + pW )sl
Ash =t a sin f
4.3.3 Side girders
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of side girders are to be not less thanthe values obtained from the following formulae:( p + pW )sl 2 3
10
w= S
0.9mRY5( p S + pW )sl
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4.3.4 Deck primary supporting members
The net scantlings of deck primary supporting members are to be not less than those obtained from the formulae in
Table 5. The design pressures in the formulae are taken from intact conditions and testing conditions respectively asstated in 2.2. For a complex deck structure, a direct strength calculation may be carried out in lieu of the formulae.
Table 5
Condition
Primary supporting members subjectedto lateral pressure in intact conditions
Primary supporting members subjectedto lateral pressure in testing conditions

Net scantlings of deck primary supporting members
Net section modulus w, in cm3w=

Net sectional shear area Ash, in cm25( pS + pW )sl
t a sin f( pS + pW )sl 2 103

Ash =pT sl 2103
1.05mRY

Ash =w=

0.9mRY

5 pT sl
1.05t a sin fwhere:

f : Angle, in deg, between the primary supporting member s web and the shell plate, measured at the middle of the
primary supporting member s span; the correction is to be applied when f is less than 75.

5.

Connection of hull structures with the rudder horn

5.1
Connection of aft peak structures with the rudder horn
5.1.1 General
The requirement of this sub-article apply to the connection between peak structure and rudder horn where thestern-frame is of an open type and is fitted with the rudder horn.
5.1.2 Rudder horn
Horn design is to be such as to enable sufficient access for welding and inspection.
The scantlings of the rudder horn, which are to comply with Ch 10, Sec 1, 9.2, may be gradually tapered inside thehull.
Connections by slot welds are not acceptable.
5.1.3 Hull structures
The vertical extension of hull structure to support the rudder horn between the horn intersection with the shell and thepeak tank top is in accordance with the requirements of Ch 10, Sec 1, 9.2.6 and 9.2.7.
The thickness of the structures adjacent to the rudder horn, such as shell plating, floors, platforms and side girders,the centreline bulkhead and any other structures, is to be adequately increased in relation to the horn scantlings.
5.2
Structural arrangement above the aft peak
5.2.1 Side transverses
Where a rudder horn is fitted, side transverses, connected to deck beams, are to be arranged between the platform
forming the peak tank top and the weather deck.
The side transverse spacing is to be not greater than:・ 2 frame spacings in way of the horn・ 4 frame spacings for and aft of the rudder horn・ 6 frame spacings in the area close to the aft peak bulkhead.
The side transverses are to be fitted with end brackets and located within the poop. Where there is no poop, thescantlings of side transverses below the weather deck are to be adequately increased with respect to those obtained fromthe formulae in 4.3.2.
5.2.2 Side girders
Where the depth from the peak tank top to the weather deck is greater than 2.6 m and the side is transversely framed,
one or more side girders are to be fitted, preferably in line with similar structures existing forward.
6.

Sternframes

6.1
General
6.1.1
Sternframes may be made of cast or forged steel, with a hollow section, or fabricated from plate.

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6.1.2
Cast steel and fabricated sternframes are to be strengthened by adequately spaced horizontal plates.
Abrupt changes of section are to be avoided in castings; all sections are to have adequate tapering radius.
6.2
Connections
6.2.1 Connection with hull structure
Sternframes are to be effectively attached to the aft structure and the lower part of the sternframe is to be extended
forward of the propeller post to a length not less than 1500 + 6LCSR-B mm, in order to provide an effective connection
with the keel. However, the sternframe need not extend beyond the aft peak bulkhead.
The net thickness of shell plating connected with the sternframe is to be not less than that obtained, in mm, from thefollowing formula:t = 8.5 + 0.045LCSR-B
6.2.2 Connection with the keel
The thickness of the lower part of the sternframes is to be gradually tapered to that of the solid bar keel or keel plate.
Where a keel plate is fitted, the lower part of the sternframe is to be so designed as to ensure an effective connection
with the keel.
6.2.3 Connection with transom floors
Rudder posts and propeller posts are to be connected with transom floors having height not less than that of the
double bottom and net thickness not less than that obtained, in mm, from the following formula:t = 9 + 0.023L1
6.2.4 Connection with centre keelson
Where the sternframe is made of cast steel, the lower part of the sternframe is to be fitted, as far as practicable, witha longitudinal web for connection with the centre keelson.
6.3
Propeller posts
6.3.1 Gross scantlings
With reference to Ch 3, Sec 2, all scantlings and dimensions referred to in 6.3.2 to 6.3.4 are gross, i.e. they include
the margins for corrosion.
6.3.2 Gross scantlings of propeller posts
The gross scantlings of propeller posts are to be not less than those obtained from the formulae in Table 6 for single
screw ships and Table 7 for twin screw ships.
Scantlings and proportions of the propeller post which differ from those above may be considered acceptableprovided that the section modulus of the propeller post section about its longitudinal axis is not less than that calculatedwith the propeller post scantlings in Table 6 or Table 7, as applicable.
6.3.3 Section modulus below the propeller shaft bossing
In the case of a propeller post without a sole piece, the section modulus of the propeller post may be gradually
reduced below the propeller shaft bossing down to 85% of the value calculated with the scantlings in Table 6 orTable 7, as applicable.
In any case, the thicknesses of the propeller posts are to be not less than those obtained from the formulae in thetables.
6.3.4 Welding of fabricated propeller post with the propeller shaft bossing
Welding of a fabricated propeller post with the propeller shaft bossing is to be in accordance with Ch 11, Sec 2.

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Table 6

Single screw ships - Gross scantlings of propeller posts

Fabricated propeller post

Cast propeller post

Bar propeller post, cast or forged,
having rectangular sectionGrossscantlings ofpropeller
posts, in mma

50 LCSR-B1/2

33 LCSR-B1/2

10 7.2 LCSR -B - 256b

35 LCSR-B1/2

23 LCSR-B1/2

10 4.6 LCSR -B - 164

t1(1)2.5 LCSR-B1/2

t2(1)

-

tD

1.3 LCSR-B1/2

R

3.2 LCSR-B1/2-

to be taken not less than 19 mm
4.4 LCSR-B1/2-

to be taken not less than 19 mm
2.0 LCSR-B1/2

-

1/2

-

50 LCSR-B-(1) Propeller post thicknesses t1, and t2 are, in any case, to be not less than (0.05LCSR-B + 9.5) mm.

Table 7

Twin screw ships - Gross scantlings of propeller posts
Cast propeller post

Fabricated propeller post

Bar propeller post, cast orforged, having rectangularsectionGross scantlingsof propeller
posts, in mma

25 LCSR-B 1/2

12.5 LCSR-B 1/2

2.4LCSR-B+6b

25 LCSR-B

1/2

25 LCSR-B 1/2

0.8LCSR-B+2

2.5 LCSR-B

1/2

2.5 LCSR-B

1/2-

3.2 LCSR-B

1/2

3.2 LCSR-B

1/2-

4.4 LCSR-B 1/2

-

1/2

-

t1

(1)

t2

(1)

t3
tD
(1)

1.3 LCSR-B

1/2

2.0 LCSR-B

Propeller post thicknesses t1, t2 and t3 are, in any case, to be not less than (0.05 LCSR-B + 9.5) mm.

6.4
Propeller shaft bossing
6.4.1
In single screw ships, the thickness of the propeller shaft bossing, included in the propeller post, is to be not less than
60% of the dimension b required in 6.3.2 for bar propeller posts with a rectangular section.
6.5
Sterntubes
6.5.1 Sterntubes
The sterntube thickness is considered by the Society on a case by case basis. In no case, however, may it be less than
the thickness of the side plating adjacent to the stern-frame.
Where the materials adopted for the sterntube and the plating adjacent to the sternframe are different, the sterntube
thickness is to be at least equivalent to that of the plating.

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Section 3

MACHINERY SPACE

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
k : Material factor, defined in Ch 3, Sec 1, 2.2
P : Maximum continuous rating, in kW, of the engine
nr : Number of revolutions per minute of the engine shaft at power equal to P
LE : Effective length, in m, of the engine foundation plate required for bolting the engine to the seating, as specified
by the engine manufacturer.

1.

General1.1
Application
1.1.1
The requirements of this Section apply for the arrangement and scantling of machinery space structures as regards
general strength. It is no substitute to machinery manufacturer s requirements that have to be dealt with at Shipyard
diligence.
1.2
Scantlings
1.2.1 Net scantlings
As specified in Ch 3, Sec 2 all scantlings referred to in this Section are net, i.e. they do not include any margin for
corrosion.
The gross scantlings are obtained as specified in Ch 3, Sec 2, 3.1.
1.2.2 General
Unless otherwise specified in this Section, the scantlings of plating, ordinary stiffeners and primary supporting
members in the machinery space are to be determined according to the relevant criteria in Ch 6.
In addition, the minimum thickness requirements specified in this Section apply.
1.2.3 Primary supporting members
The Designer may propose arrangements and scantlings alternative to the requirements of this Section, on the basisof direct calculations which are to be submitted to the Society for examination on a case by case basis.
The Society may also require such direct calculations to be carried out whenever deemed necessary.
1.3
Connections of the machinery space with structures located aft and forward
1.3.1 Tapering
Adequate tapering is to be ensured between the scantlings in the machinery space and those aft and forward. The
tapering is to be such that the scantling requirements for all areas are fulfilled.
1.3.2 Transition zone between engine room and cargo area
In the transition zone between the engine room and the aftermost cargo hold due consideration is to be given to theproper tapering of major longitudinal members within the engine room such as flats, decks, horizontal rings or sidestringers into the cargo hold, and for longitudinal bulkheads (inner skin, upper and lower wing tank) into the engine
room.
Where such structure is in line with longitudinal members aft or forward of the cargo hold bulkhead, adequate
tapering is to be achieved by fitting large tapering brackets inside the wing tanks or engine room.
1.3.3 Deck discontinuities
Decks which are interrupted in the machinery space are to be tapered on the side by means of horizontal brackets.

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2.

Double bottom

2.1
Arrangement
2.1.1 General
Where the machinery space is immediately forward of the after peak, in general, the double bottom is to betransversely framed. In all other cases it may be transversely or longitudinally framed.
2.1.2 Double bottom heightThe double bottom height at the centreline, irrespective of the location of the machinery space, is to be not less thanthe value defined in Ch 3, Sec 6, 6.1. This depth may need to be considerably increased in relation to the type and depthof main machinery seatings.
The above height is to be increased by the Shipyard where the machinery space is very large and where there is aconsiderable variation in draught between light ballast and full load conditions.
Where the double bottom height in the machinery space differs from that in adjacent spaces, structural continuity of
longitudinal members is to be ensured by sloping the inner bottom over an adequate longitudinal extent. The knuckles
in the sloped inner bottom are to be located in way of floors.
2.1.3 Centre bottom girder
In general, the centre bottom girder may not be provided with holes. In any case, in way of any openings formanholes on the centre girder, permitted only where absolutely necessary for double bottom access and maintenance,
local strengthening is to be arranged.
2.1.4 Side bottom girders
In the machinery space the number of side bottom girders is to be adequately increased, with respect to the adjacentareas, to ensure adequate rigidity of the structure. The side bottom girders are to be a continuation of any bottom
longitudinals in the areas adjacent to the machinery space and are generally to have a spacing not greater than 3 times
that of longitudinals and in no case greater than 3 m.
2.1.5 Side bottom girders in way of machinery seatings
Additional side bottom girders are to be fitted in way of machinery seatings.
Side bottom girders arranged in way of main machinery seatings are to extend for the full length of the machinery
space.
Bottom girders are to extend as far aft as practicable in relation to the shape of the bottom and are to be supported byfloors and side primary supporting members at the ends.
Forward of the machinery space forward bulkhead, the bottom girders are to be generally tapered for at least threeframe spaces and are to be effectively connected to the hull structure.
2.1.6 Floors in longitudinally framed double bottom
Where the double bottom is longitudinally framed, the floor spacing is to be not greater than:
・ 1 frame spacing in way of the main engine and thrust bearing
・ 2 frame spacings in other areas of the machinery space.
Additional floors are to be fitted in way of other important machinery.
2.1.7 Floors in transversely framed double bottom
Where the double bottom in the machinery space is transversely framed, floors are to be arranged at every frame.
Furthermore, additional floors are to be fitted in way of boiler foundations or other important machinery.
2.1.8 Floors stiffeners
In addition to the requirements in Ch 3, Sec 6, floors are to have web stiffeners sniped at the ends and spaced not
more than approximately 1 m apart.
The section modulus of web stiffeners is to be not less than 1.2 times that required in Ch 6, Sec 2, 4.1.2.
2.1.9 Manholes and wells
The number and size of manholes in floors located in way of seatings and adjacent areas are to be kept to theminimum necessary for double bottom access and maintenance.
The depth of manholes is generally to be not greater than 40% of the floor local depth, and in no case greater than 750
mm, and their width is to be equal to approximately 400 mm.
In general, manhole edges are to be stiffened with flanges; failing this, the floor plate is to be adequately stiffenedwith flat bars at manhole sides.

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Manholes with perforated portable plates are to be fitted in the inner bottom in the vicinity of wells arranged close to
the aft bulkhead of the engine room.
Drainage of the tunnel is to be arranged through a well located at the aft end of the tunnel.
2.2
Minimum thicknesses
2.2.1
The net thicknesses of inner bottom, floor and girder webs are to be not less than the values given in Table 1.
Table 1

Double bottom - Minimum net thicknesses of inner bottom, floor and girder webs

Element

Minimum net thickness, in mm

Inner bottom

6.6 + 0.024LCSR-B
The Society may require the thickness of the inner bottom in way of the machinery seatingsand on the main thrust blocks to be increased, on a case by case basis.

Margin plate

0.9LCSR-B1/2 + 1

Centre girder

1.55LCSR-B1/3 + 3.5

Floors and side girders

1.7LCSR-B1/3 +1

Girder bounding a duct keel

0.8LCSR-B1/2 + 2.5 , to be taken not less than that required for the centre girder.

3.

Side

3.1
Arrangement
3.1.1 General
The type of side framing in machinery spaces is generally to be the same as that adopted in the adjacent areas.
3.1.2 Extension of the hull longitudinal structure within the machinery space
In ships where the machinery space is located aft and where the side is longitudinally framed, the longitudinal
structure is preferably to extend for the full length of the machinery space.
In any event, the longitudinal structure is to be maintained for at least 0.3 times the length of the machinery space,calculated from the forward bulkhead of the latter, and abrupt structural discontinuities between longitudinally andtransversely framed structures are to be avoided.
3.1.3 Side transverses
Side transverses are to be aligned with floors. One is preferably to be located in way of the forward end and anotherin way of the after end of the machinery casing.
For a longitudinally framed side, the side transverse spacing is to be not greater than 4 frame spacings.
For a transversely framed side, the side transverse spacing is to be not greater than 5 frame spaces. The web height is
to be not less than twice that of adjacent frames and the section modulus is to be not less than four times that of adjacentframes.
Side transverse spacing greater than that above may be accepted provided that the scantlings of ordinary frames are
increased, according to the Society s requirements to be defined on a case by case basis.
4.

Platforms

4.1
Arrangement
4.1.1 General
The location and extension of platforms in machinery spaces are to be arranged so as to be a continuation of thestructure of side longitudinals, as well as of platforms and side girders located in the adjacent hull areas.
4.1.2 Platform transverses
In general, platform transverses are to be arranged in way of side or longitudinal bulkhead transverses.
For longitudinally framed platforms, the spacing of platform transverses is to be not greater than 4 frame spacings.
4.2
Minimum thicknesses
4.2.1
The net thickness of platforms is to be not less than 6.5 mm.

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5.

Pillaring

5.1
Arrangement
5.1.1 General
The pillaring arrangement in machinery spaces is to account both for the concentrated loads transmitted bymachinery and superstructures and for the position of main machinery and auxiliary engines.
5.1.2 Pillars
Pillars are to be arranged in the following positions:・ in way of machinery casing corners and corners of large openings on platforms; alternatively, two pillars may befitted on the centreline (one at each end of the opening)・ in way of the intersection of platform transverses and girders
・ in way of transverse and longitudinal bulkheads of the superstructure.
In general, pillars are to be fitted with brackets at their ends.
5.1.3 Pillar bulkheads
In general, pillar bulkheads, fitted in tween decks below the upper deck, are to be located in way of load-bearing
bulkheads in the superstructures.
Longitudinal pillar bulkheads are to be a continuation of main longitudinal hull structures in the adjacent spaces
forward and aft of the machinery space.
Pillar bulkhead scantlings are to be not less than those required in 6.3 for machinery casing bulkheads.
6.

Machinery casing

6.1
Arrangement
6.1.1 Ordinary stiffener spacing
Ordinary stiffeners are to be located:
・ at each frame, in longitudinal bulkheads
・ at a distance of about 750 mm, in transverse bulkheads.
The ordinary stiffener spacing in portions of casings that are particularly exposed to wave action is considered by theSociety on a case by case basis.
6.2
Openings
6.2.1 General
All machinery space openings, which are to comply with the requirements in Sec 6, 6, are to be enclosed in a steel
casing leading to the highest open deck. Casings are to be reinforced at the ends by deck beams and girders associatedto pillars.
In the case of large openings, the arrangement of cross-ties as a continuation of deck beams may be required.
Skylights, where fitted with openings for light and air, are to have coamings of a height not less than:・ 900 mm, if in position 1
・ 760 mm, if in position 2.
6.2.2 Access doors
Access doors to casings are to comply with Sec 6, 6.2.
6.3
Scantlings
6.3.1 Plating and ordinary stiffeners
The net scantlings of plating and ordinary stiffeners are to be not less than those obtained according to the applicablerequirements in Ch 9, Sec 4.
6.3.2 Minimum thicknesses
The net thickness of bulkheads is to be not less than:・ 5.5 mm for bulkheads in way of cargo holds
・ 4 mm for bulkheads in way of accommodation spaces.

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7.

Main machinery seating

7.1
Arrangement
7.1.1 General
The scantlings of main machinery seatings and thrust bearings are to be adequate in relation to the weight and powerof engines and the static and dynamic forces transmitted by the propulsive installation.
7.1.2 Seating supporting structure
Transverse and longitudinal members supporting the seatings are to be located in line with floors and double orsingle bottom girders, respectively.
They are to be so arranged as to avoid discontinuity and ensure sufficient accessibility for welding of joints and forsurveys and maintenance.
7.1.3 Seatings included in the double bottom structure
Where high-power internal combustion engines or turbines are fitted, seatings are to be integral with the double
bottom structure. Girders supporting the bedplates in way of seatings are to be aligned with double bottom girders andare to be extended aft in order to form girders for thrust blocks.
The girders in way of seatings are to be continuous from the bedplates to the bottom shell.
7.1.4 Seatings above the double bottom plating
Where the seatings are situated above the double bottom plating, the girders in way of seatings are to be fitted withflanged brackets, generally located at each frame and extending towards both the centre of the ship and the sides.
The extension of the seatings above the double bottom plating is to be limited as far as practicable while ensuring
adequate spaces for the fitting of bedplate bolts. Bolt holes are to be located such that they do not interfere with seating
structures.
7.1.5 Seatings in a single bottom structure
For ships having a single bottom structure within the machinery space, seatings are to be located above the floors andto be adequately connected to the latter and to the girders located below.
7.1.6 Number of girders in way of machinery seatings
At least two girders are to be fitted in way of main machinery seatings.
One girder may be fitted only where the following three formulae are complied with:
LCSR-B < 150 m
P < 7100 kW
P < 2.3 nr LE
7.2
Minimum scantlings
7.2.1
The net scantlings of the structural elements in way of the internal combustion engine seatings are to be obtained
from the formulae in Table 2. However, the net cross-sectional area of each bedplate of the seatings may be determinedby the engine manufacturers, provided the information regarding permissible foundation stiffness considering theengine characteristics and engine room arrangement, etc.

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Table 2

Minimum scantlings of the structural elements in way of machinery seatings
Scantling minimum value

Scantling minimum value

2

P
nr LE

Net cross-sectional area, in cm , of each bedplate of the seatings

40 + 70

Bedplate net thickness, in mm

Bedplates supported by two or more girders:
240 + 175

P
nr LE

Bedplates supported by one girder:
5 + 240 + 175

Total web net thickness, in mm, of girders fitted in way of machinery
seatingsP
n r LE

Bedplates supported by two or more girders:
320 + 215

P
n r LE

Bedplates supported by one girder:

Web net thickness, in mm, of floors fitted in way of machinery seatings－315－

95 + 65

P
n r LE

55 + 40P
nr LE

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 4)

Section 4

SUPERSTRUCTURES AND DECKHOUSES

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
L2 : Rule length LCSR-B, but to be taken not greater than 300 m
pD : Lateral pressure for decks, in kN/m2, as defined in 3.2.1
pSI : Lateral pressure for sides of superstructures, in kN/m2, as defined in 3.2.3
k : Material factor, defined in Ch 3, Sec 1, 2.2
s : Spacing, in m, of ordinary stiffeners, measured at mid-span along the chordl : Span, in m, of ordinary stiffeners, measured between the supporting members, see Ch 3, Sec 6, 4.2
c : Coefficient taken equal to:c = 0.75 for beams, girders and transverses which are simply supported on one or both ends
c = 0.55 in other cases
ma : Coefficient taken equal to:2
sé æsö ùsm a = 0.204 ê4 - çú , with £ 1ll êë è l ø úû

1.

General1.1
Definitions
1.1.1 Superstructure
See Ch 1, Sec 4, 3.12.1
1.1.2 Deckhouse
See Ch 1, Sec 4, 3.15.1
1.1.3 Long deckhouse
A long deckhouse is a deckhouse the length of which within 0.4LCSR-B amidships exceeds 0.2LCSR-B. The strength of along deckhouse is to be specially considered.
1.1.4 Short deckhouse
A short deckhouse is a deckhouse not covered by the definition given in 1.1.3.
1.1.5 Non-effective superstructure
For the purpose of this section, all superstructures being located beyond 0.4LCSR-B amidships or having a length ofless than 0.15LCSR-B are considered as non-effective superstructures.
1.1.6 Insulated funnel
Scantlings of insulated funnels are to be determined as for deckhouses.
1.1.7 Effective superstructure
Effective superstructure is a superstructure not covered by the definition given in 1.1.5.
1.2
Gross scantlings
1.2.1
With reference to Ch 3, Sec 2, all scantlings and dimensions referred to in 4 and 5 are gross, i.e. they include themargins for corrosion.
2.

Arrangement

2.1
Strengthening at the ends of superstructures
2.1.1
In way of end bulkheads of superstructures located within 0.4LCSR-B amidships, the thickness of the strength deck in abreadth of 0.1B from the shell, the thickness of the sheerstrake, and the thickness of the superstructure side plating are－316－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 4)

to be increased by the percentage of strengthening specified in Table 1. The strengthening is to be extended over a
region from 4 frame spacings abaft the end bulkhead to 4 frame spacings forward of the end bulkhead.
Table 1

Percentage of strengthening
Strength deck andSide plating ofsheerstrakesuperstructure

Effective

30%

20%

Non-effective

20%

10%

Type of superstructure

2.1.2
Under strength decks in way of 0.6LCSR-B amidships, girders are to be fitted in alignment with longitudinal walls,
which are to extend at least over three frame spacings beyond the end points of the longitudinal walls. The girders are tooverlap with the longitudinal walls by at least two frame spacings.
2.2
Attachment of stiffening members
2.2.1 Attachment of deck beams
Transverse deck beams are to be connected to the frames by brackets according to Ch 3, Sec 6.
Deck beams crossing longitudinal walls and girders may be attached to the stiffeners of longitudinal walls and thewebs of girders respectively by welding without brackets.
2.2.2 Attachment of deck girders and transverses
End attachments of girders at bulkheads are to be so dimensioned that the bending moments and shear forces can betransferred. Bulkhead stiffeners under girders are to be sufficiently dimensioned to support the girders.
Face plates are to be stiffened by tripping brackets according to Ch 3, Sec 6. At girders of symmetrical section, they
are to be arranged alternately on both sides of the web.
2.2.3 End attachment of superstructure frames
Superstructure frames are to be connected to the main frames below, or to the deck. The end attachment may be
carried out in accordance with Fig. 1.
Fig. 1

End attachment of superstructure frames

2.3
Transverse structure of superstructures and deckhouses
2.3.1
The transverse structure of superstructures and deckhouses is to be sufficiently dimensioned by a suitablearrangement of end bulkheads, web frames, steel walls of cabins and casings, or by other measures.
2.4
Openings in enclosed superstructures
2.4.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 12(1))
All access openings in bulkheads at ends of enclosed superstructures are to be fitted with weathertight doors
permanently attached to the bulkhead, and framed, stiffened and fitted so that the whole structure is of equivalent
strength to the un-pierced bulkhead. The doors are to be so arranged that they can be operated from both sides of thebulkhead.
2.4.2
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 12(3))
The height of the sills of access openings in bulkheads at ends of enclosed superstructures shall be at least 380 mm
above the deck.
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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 4)

2.4.3
Any opening in a superstructure deck or in a deckhouse deck directly above the freeboard deck (deckhousesurrounding companionways), is to be protected by efficient weathertight closures.
3.

Load model

3.1
Load calculation point
3.1.1
Unless otherwise specified, lateral pressure is to be calculated at load calculation points defined in:・ Ch 6, Sec 1, 1.5, for plating
・ Ch 6, Sec2, 1.4 for ordinary stiffeners and primary supporting members.
3.2
Loads
3.2.1 Lateral pressure for decks
The lateral pressure for decks of superstructures and deckhouses, in kN/m2, is to be taken equal to:・ the external pressure pD defined in Ch 4, Sec 5, 2.1 for exposed decks
・ 5 kN/m2 for unexposed decks
3.2.2 Lateral pressure for exposed wheel house top
The lateral pressure p for exposed wheel house tops, in kN/m2, is to be obtained according to Ch 4, Sec 5, 3.2.
3.2.3 Lateral pressure for sides of superstructures
The lateral pressure pSI for sides of superstructures, in kN/m2, is to be obtained according to Ch 4, Sec 5, 3.3.
4.

Scantlings

4.1
Side plating of non-effective superstructures
4.1.1
The thickness, in mm, of the side plating of non-effective superstructures is not to be less than the greater of thefollowing values:t = 1.21s kp SI + 1.5

t = 0.8 kLCSR - B

4.2
Deck plating of non-effective superstructures
4.2.1
The thickness, in mm, of deck plating of non-effective superstructures is not to be less than the greater of thefollowing values:t = 1.21s kp D + 1.5

t = (5.5 + 0.02 LCSR - B ) k

where LCSR-B is not to be taken greater than 200 m.
4.2.2
Where additional superstructures are arranged on non-effective superstructures located on the freeboard deck, thegross thickness required by 4.2.1 may be reduced by 10%.
4.2.3
Where plated decks are protected by sheathing, the gross thickness of the deck plating according to 4.2.1 and 4.2.2
may be reduced by 1.5 mm. However, such deck plating is not to be less than 5 mm.
Where a sheathing other than wood is used, attention is to be paid that the sheathing does not affect the steel. The
sheathing is to be effectively fitted to the deck.
4.3
Deck beams and supporting deck structure
4.3.1 Transverse deck beams and deck longitudinal ordinary stiffeners
The section modulus w, in cm3, and the shear area Ash, in cm2, of transverse deck beams and of deck longitudinal
ordinary stiffeners are not to be less than the values obtained from the following formulae:
w = ckp D sl 2
Ash = 0.05(1 - 0.817m a )kp D sl

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 4)

4.3.2 Deck girders and transverses
The section modulus w, in cm3, and the shear area Ash, in cm2, of deck girders and transverses are not to be less thanthe values obtained from the following formulae:
w = ckp D el 2
Ash = 0.05kp D el
where:
e : Width of loaded area, in m, of the unsupported adjacent plate fields, measured from each mid of plate field
to mid of opposite plate filed.
The girder depth is not to be less than l 25 . The web depth of girders scalloped for continuous deck beams is to beat least 1.5 times the depth of the deck beams.
Where a girder does not have the same section modulus throughout all girder fields, the greater scantlings are to be
maintained above the supports and are to be reduced gradually to the smaller scantlings.
4.4
Superstructure frames
4.4.1 Section modulus and shear area
The section modulus w, in cm3, and the shear area Ash, in cm2, of the superstructure frames are not to be less than thevalues obtained from the following formulae:
w = 0.55kp SI sl 2
Ash = 0.05(1 - 0.817m a )kp SI sl
4.4.2
Where frames are supported by a longitudinally framed deck, the frames fitted between web frames are to beconnected to the adjacent longitudinal ordinary stiffeners by brackets. The scantlings of the brackets are to be
determined in accordance with Ch 3, Sec 6 on the basis of the section modulus of the frames.
4.4.3
Where further superstructures or deckhouses are arranged on the superstructures, strengthening of the frames of thespace below may be required.
4.5
Decks of short deckhouses
4.5.1 Plating
The thickness, in mm, of weather deck of short deckhouses and is not to be less than:t = 8 s k + 1.5

For weather decks of short deckhouses protected by sheathing and for decks within deckhouses, the gross thickness
may be reduced by 1.5 mm. However, such deck plating is not to be less than 5 mm.
4.5.2 Deck beams
The scantlings of deck beams and supporting deck structure are to be determined according to 4.3.
5.

End bulkheads of superstructure and deckhouse

5.1
Application
5.1.1
The requirements in 5.2 and 5.3 apply to end bulkheads of superstructure and deckhouse forming the only protection
for openings, as required by ILLC as amended, and for accommodations.
5.2
Loads
5.2.1
The design load p A , in kN/m2, for determining the scantlings is to be obtained according to Ch 4, Sec 5, 3.4.
5.3
Scantlings
5.3.1 Stiffeners
The section modulus w, in cm3, of the stiffeners is not to be less than the value obtained from the following formula:w = 0.35kp A sl 2This requirement assume the webs of lowest tier stiffeners to be efficiently welded to the decks. Scantlings for othertypes of end connections may be specially considered.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 4)

The section modulus of deckhouse side stiffeners needs not to be greater than that of side frames on the deck situateddirectly below; taking account of spacing s and span l .
5.3.2 Plate thickness
The gross thickness of the plating, in mm, is not to be less than the greater of the values obtained from the following
formulae:t = 0.9 s kpA + 1.5

L öæ
t min = çç 5.0 + 2
k , for the lowest tier
100
è
ø
L ö
æ
t min = çç 4.0 + 2
k , for the upper tiers, without being less than 5.0 mm.
100 ø
è

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

Section 5

HATCH COVERS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
pS : Still water pressure, in kN/m2, defined in 4.1
pW : Wave pressure, in kN/m2, defined in 4.1
pC : Pressure acting on the hatch coaming, in kN/m2, defined in 6.2
FS, FW : Coefficients taken equal to:for ballast water loads on hatch covers of the ballast holdFS = 0 and FW = 0.9
in other cases
FS = 1.0 and FW = 1.0
s : Length, in m, of the shorter side of the elementary plate panell : Length, in m, of the longer side of the elementary plate panel
bp : Effective width, in m, of the plating attached to the ordinary stiffener or primary supporting member, defined in3
w : Net section modulus, in cm3, of the ordinary stiffener or primary supporting member, with an attached plating ofwidth bp
Ash : Net shear sectional area, in cm2, of the ordinary stiffener or primary supporting memberm : Boundary coefficient for ordinary stiffeners and primary supporting members, taken equal to:m = 8 , in the case of ordinary stiffeners and primary supporting members simply supported at both ends or
supported at one end and clamped at the other end
m = 12 , in the case of ordinary stiffeners and primary supporting members clamped at both ends
tC : Total corrosion addition, in mm, defined in 1.4
sa, ta : Allowable stresses, in N/mm2, defined in 1.5

1.

General1.1
Application
1.1.1
The requirements in 1 to 8 apply to steel hatch covers in positions 1 and 2 on weather decks, defined in Ch 1, Sec 4,
3.20.
The requirements in 9 apply to steel hatch covers of small hatches fitted on the exposed fore deck over the forward
0.25LCSR-B.
1.2
Materials
1.2.1 SteelThe formulae for scantlings given in 5 are applicable to steel hatch covers.
Materials used for the construction of steel hatch covers are to comply with the applicable requirements of theSociety.
1.2.2 Other materials
The use of materials other than steel is considered by the Society on a case by case basis, by checking that criteria
adopted for scantlings are such as to ensure strength and stiffness equivalent to those of steel hatch covers.
1.3
Net scantlings
1.3.1
All scantlings referred to in this Section, except otherwise specified, are net, i.e. they do not include any margin for
corrosion.
When calculating the stresses s and t in 5.3 and 5.4, the net scantlings are to be used.
The gross scantlings are obtained as specified in Ch 3, Sec 2.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

The corrosion additions are given in 1.4.
1.4
Corrosion additions
1.4.1
The total corrosion addition for both sides to be considered for the plating and internal members of hatch covers isequal to the value specified in Table 1.
The corrosion addition for hatch coamings and coaming stays is defined according to Ch 3, Sec 3.
Corrosion addition tC for hatch covers

Table 1

Corrosion addition tC, in mm, for both sides
Plating and stiffeners of single skin hatch cover

2.0

Top and bottom plating of double skin hatch cover

2.0

Internal structures of double skin hatch cover

1.5

1.5
Allowable stresses
1.5.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 15(6) and 16(5))
The allowable stresses sa and ta, in N/mm2, are to be obtained from Table 2.
Table 2
Members of
Weathertight hatch cover
Pontoon hatch cover
Weathertight hatch cover andpontoon hatch cover2.

Allowable stresses, in N/mm2
Subjected tosa, in N/mm2

ta, in N/mm2

External pressure, as defined in

0.80 ReH

0.46 ReH

Ch 4, sec 5, 5.2.1

0.68 ReH

0.39 ReH

0.90 ReH

0.51 ReH

Other loads, as defined in Ch
4 ,Sec 5, 5.1.1 and Ch 4, Sec 6, 2

Arrangements

2.1
Height of hatch coamings
2.1.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 14 (1, 1))
The height above the deck of hatch coamings is to be not less than:・ 600 mm in position 1・ 450 mm in position 2.
2.1.2
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 14 (1, 2))
The height of hatch coamings in positions 1 and 2 closed by steel covers provided with gaskets and securing devices
may be reduced with respect to the above values or the coamings may be omitted entirely, on condition that the Society
is satisfied that the safety of the ship is not thereby impaired in any sea conditions.
In such cases the scantlings of the covers, their gasketing, their securing arrangements and the drainage of recesses inthe deck are considered by the Society on a case by case basis.
2.1.3
Regardless of the type of closing arrangement adopted, the coamings may have reduced height or be omitted in wayof openings in closed superstructures.
2.2
Hatch covers
2.2.1
Hatch covers on exposed decks are to be weathertight.
Hatch covers in closed superstructures need not be weathertight.
However, hatch covers fitted in way of ballast tanks, fuel oil tanks or other tanks are to be watertight.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

2.2.2
The ordinary stiffeners and primary supporting members of the hatch covers are to be continuous over the breadthand length of the hatch covers, as far as practical. When this is impractical, sniped end connections are not to be used
and appropriate arrangements are to be adopted to ensure sufficient load carrying capacity.
2.2.3
The spacing of primary supporting members parallel to the direction of ordinary stiffeners is to be not greater than
1/3 of the span of primary supporting members.
2.2.4
The breadth of the primary supporting member face plate is to be not less than 40% of their depth for laterally
unsupported spans greater than 3 m. Tripping brackets attached to the face plate may be considered as a lateral support
for primary supporting members.
The face plate outstand is not to exceed 15 times the gross face plate thickness.
2.2.5
Efficient retaining arrangements are to be provided to prevent translation of the hatch cover under the action of thelongitudinal and transverse forces exerted by cargoes on the cover, if any. These retaining arrangements are to belocated in way of the hatch coaming side brackets.
2.2.6
The width of each bearing surface for hatch covers is to be at least 65 mm.
2.3
Hatch coamings
2.3.1
Coamings, stiffeners and brackets are to be capable of withstanding the local forces in way of the clamping devices
and handling facilities necessary for securing and moving the hatch covers as well as those due to cargo stowed on thelatter.
2.3.2
Special attention is to be paid to the strength of the fore transverse coaming of the forward hatch and to the scantlingsof the closing devices of the hatch cover on this coaming.
2.3.3
Longitudinal coamings are to be extended at least to the lower edge of deck beams.
・ where they are not part of continuous deck girders, the lower edge of longitudinal coamings are to extend for atleast two frame spaces beyond the end of the openings.
・ where longitudinal coamings are part of deck girders, their scantlings are to be as required in Ch 6, Sec 4.
2.3.4
A web frame or a similar structure is to be provided below the deck in line with the transverse coaming. Transverse
coamings are to extend below the deck and to be connected with the web frames.
2.4
Small hatchways
2.4.1
The height of small hatchway coamings is to be not less than 600 mm if located in position 1 and 450 mm if located inposition 2.
Where the closing appliances are in the form of hinged steel covers secured weathertight by gaskets and swing bolts,
the height of the coamings may be reduced or the coamings may be omitted altogether.
2.4.2
Small hatch covers are to have strength equivalent to that required for main hatchways and are to be of steel,weathertight and generally hinged.
Securing arrangements and stiffening of hatch cover edges are to be such that weathertightness can be maintained inany sea condition.
At least one securing device is to be fitted at each side. For small circular coamings, hinges are considered equivalent
to securing devices.
2.4.3
Hold accesses located on the weather deck are to be provided with weathertight metallic hatch covers, unless they areprotected by a closed superstructure. The same applies to accesses located on the forecastle deck and leading directly toa dry cargo hold through a trunk.
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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

2.4.4
Accesses to cofferdams and ballast tanks are to be manholes fitted with watertight covers fixed with bolts which are
sufficiently closely spaced.
2.4.5
Hatchways of special design are considered by the Society on a case by case basis.
3.

Width of attached plating

3.1
Ordinary stiffeners
3.1.1
The width of the attached plating to be considered for the check of ordinary stiffeners is to be obtained, in m, from thefollowing formulae:
・ where the attached plating extends on both sides of the stiffener:
bp = s・ where the attached plating extends on one side of the stiffener:b p = 0.5s
3.2
Primary supporting members
3.2.1
The effective width of the attached plating to be considered for the yielding and buckling checks of primary
supporting members analysed through isolated beam or grillage model is to be obtained, in m, from the following
formulae:・ where the plating extends on both sides of the primary supporting member:b p = b p ,1 + b p , 2・ where the plating extends on one side of the primary supporting member:b p = b p ,1
where:(

b p ,1 = min 0.165l p , S p ,1()

b p , 2 = min 0.165l p , S p , 2)

lp: Span, in m, of the considered primary supporting member
Sp,1, Sp,2 : Half distance, in m, between the considered primary supporting member and the adjacent ones, Sp,1
for one side, Sp,2 for the other side.
When a isolated beam or a grillage analysis is used, the areas of ordinary stiffeners are not to be included in theattached plating of the primary members.
4.

Load model

4.1
Lateral pressures and forces
4.1.1 General
The lateral pressures and forces to be considered as acting on hatch covers are indicated in 4.1.2 to 4.1.6. When two
or more panels are connected by hinges, each individual panel is to be considered separately.
In any case, the sea pressures defined in 4.1.2 are to be considered for hatch covers located on exposed decks.
Additionally, when the hatch cover is intended to carry uniform cargoes, special cargoes or containers, the pressuresand forces defined in 4.1.3 to 4.1.6 are to be considered independently from the sea pressures.
4.1.2 Sea pressures
The still water and wave lateral pressures are to be considered and are to be taken equal to:・ still water pressure: p S = 0
・ wave pressure pW , as defined in Ch 4, Sec 5, 5.2.
4.1.3 Internal pressures due to ballast waterIf applicable, the static and dynamic lateral pressures are to be considered and are defined in Ch 4, Sec 6, 2.
4.1.4 Pressures due to uniform cargoes
If applicable, the static and dynamic pressures are to be considered and are defined in Ch 4, Sec 5, 2.4.1.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

4.1.5 Pressures or forces due to special cargoes
In the case of carriage on the hatch covers of special cargoes (e.g. pipes, etc.) which may temporarily retain water
during navigation, the lateral pressures or forces to be applied are considered by the Society on a case by case basis.
4.1.6 Forces due to containers
In the case of carriage of containers on the hatch covers, the concentrated forces under the containers corners are to
be determined in accordance with the applicable requirements of the Society.
4.2
Load point
4.2.1 Sea pressures
The wave lateral pressure to be considered as acting on each hatch cover is to be calculated at a point locatedlongitudinally, at the hatch cover mid-length.
4.2.2 Other pressures
The lateral pressure is to be calculated:
・ in way of the geometrical centre of gravity of the plate panel, for plating・ at mid-span, for ordinary stiffeners and primary supporting members.
Internal dynamic lateral pressure to be considered as acting on the bottom of a hatch cover is to be calculated at apoint located:
・ longitudinally, at the hatch cover mid-length
・ transversely, at hatchway side・ vertically, at the top of the hatch coaming for internal ballast water pressures
5.

Strength check

5.1
General5.1.1 Application
The strength check is applicable to rectangular hatch covers subjected to a uniform pressure, designed with primary
supporting members arranged in one direction or as a grillage of longitudinal and transverse primary supporting
members.
In the latter case, the stresses in the primary supporting members are to be determined by a grillage or a finite element
analysis.
It is to be checked that stresses induced by concentrated loads are in accordance with the criteria in 5.4.4.
5.1.2 Hatch covers supporting containers
The scantlings of hatch covers supporting containers are to comply with the applicable provisions of the Society.
5.1.3 Hatch covers subjected to special cargoes
For hatch covers supporting special cargoes, ordinary stiffeners and primary supporting members are generally to bechecked by direct calculations, taking into account the stiffener arrangements and their relative inertia. It is to bechecked that stresses induced by special cargoes are in accordance with the criteria in 5.4.4.
5.1.4 Covers of small hatchways
The gross thickness of covers is to be not less than 8 mm. This thickness is to be increased or an efficient stiffening
fitted to the Society's satisfaction where the greatest horizontal dimension of the cover exceeds 0.6 m.
5.2
Plating
5.2.1 Net thickness
The net thickness of steel hatch cover top plating, in mm, is to be not less than the value obtained from the following
formula:t = 15.8F p s

FS p S + FW pW
0.95 ReH

where:
Fp : Factor for combined membrane and bending response, equal to:
F p = 1.5 in generalF p = 1.9 s s a , for s ³ 0.8s a for the attached plating of primary supporting members－325－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5): Normal stress, in N/mm2, in the attached plating of primary supporting members, calculated according to
5.4.3 or determined through a grillage analysis or a finite element analysis, as the case may be.
5.2.2 Minimum net thickness
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 16 (5, c))
In addition to 5.2.1, the net thickness, in mm, of the plating forming the top of the hatch cover is to be not less than thegreater of the following values:t = 10ss

t=65.2.3 Critical buckling stress check
The compressive stress s in the hatch cover plating, induced by the bending of primary supporting members, parallelto the direction of ordinary stiffeners is to comply with the following formula:
0.88
s£
s C1
S
where:
S : Safety factor defined in Ch 6, Sec 3
sC1 : Critical buckling stress, in N/mm2, taken equal to:R
s C1 = s E1
fors E1 £ eH
2
æ
ReH ö
ReH
for
s C1 = ReH çç1 s E1 >2
è 4s E1 ø2

æ t ö
s E 1 = 3 .6 E çè 1000s øt: Net thickness, in mm, of plate panel
The compressive stress s in the hatch cover plating, induced by the bending of primary supporting members,
perpendicular to the direction of ordinary stiffeners is to comply with the following formula:
0.88
sC2
S
where:
S : Safety factor defined in Ch 6, Sec 3
sC2 : Critical buckling stress, in N/mm2, taken equal to:R
sC 2 = s E2
fors E 2 £ eH
2
æ
R ö
R
for
s C 2 = ReH çç1 - eH
s E 2 > eH2
è 4s E 2 ø

s£

2

m

æ t ö
s E 2 = 0.9 m E çç
è 1000ss ø: Coefficient taken equal to:
2

t
ss
ls
y

c

é æ s ö2 ù
2.1
m = c ê1 + çç s úly+ 1 .1êë è s ø úû
: Net thickness, in mm, of plate panel: Length, in m, of the shorter side of the plate panel: Length, in m, of the longer side of the plate panel: Ratio between smallest and largest compressive stress: Coefficient taken equal to:c = 1.3
when plating is stiffened by primary supporting members
c = 1.21
when plating is stiffened by ordinary stiffeners of angle or T typec = 1.1
when plating is stiffened by ordinary stiffeners of bulb typec = 1.05
when plating is stiffened by flat bar.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

c = 1.30
when plating is stiffened by ordinary stiffeners of U type. The higher c value but not
greater than 2.0 may be taken if it is verified by buckling strength check of panel using non-linear FEA anddeemed appropriate by the Society.
An averaged value of c is to be used for plate panels having different edge stiffeners.
The bi-axial compression stress in the hatch cover plating, when calculated by means of finite element analysis, is tocomply with the requirements in Ch 6, Sec 3.
5.3
Ordinary stiffeners
5.3.1
For flat bar ordinary stiffeners, the ratio hw t w is to comply with the following formula:
hw
235
£ 15
tw
ReH

5.3.2 Minimum net thickness of web
The web net thickness of the ordinary stiffener, in mm, is to be not less than 4mm.
5.3.3 Net section modulus and net shear sectional area
The net section modulus w, in cm3, and the net shear sectional area Ash, in cm2, of an ordinary stiffener subject tolateral pressure are to be not less than the values obtained from the following formulae:( F p + FW pW ) sl 2s 3
w= S S
10
ms a
Ash =

5( FS p S + FW pW ) sl stawhere:
ls : Ordinary stiffener span, in m, to be taken as the spacing, in m, of primary supporting members or the
distance between a primary supporting member and the edge support, as applicable. When brackets are
fitted at both ends of all ordinary stiffener spans, the ordinary stiffener span may be reduced by an amountequal to 2/3 of the minimum brackets arm length, but not greater than 10% of the gross span, for eachbracket.
5.3.4 Critical buckling stress check
The compressive stress s in the face plate of ordinary stiffeners, induced by the bending of primary supporting
members, parallel to the direction of ordinary stiffeners is to comply with the following formula:
0.88s CSs£
S
where:
S : Safety factor defined in Ch 6, Sec 3
sCS : Critical buckling stress, in N/mm2, taken equal to:R
s CS = s ES
fors ES £ eH
2
æ
ReH ö
ReH
for
s CS = ReH çç1 s ES >2
è 4s ES øIaAls ES = min (s E 3 , s E 4 )EI
s E 3 = 0.001 a2
Al: Moment of inertia, in cm4, of the ordinary stiffener, including a face plate equal to spacing of ordinary
stiffeners: Cross-sectional area, in cm2, of the ordinary stiffener, including a face plate equal to spacing of ordinary
stiffeners: Span, in m, of the ordinary stiffener
p2 E I æK ö
Is E 4 = 4 w2 ç m 2 + 2 + 0.385 E t
Ip
10 I p l è
m ø
K=

C l4
10 6
p 4 E Iw

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)m: Number of half waves, given in Table 3.
Table 3

m

Iw

0<K<4

4 < K < 36

36 < K < 144(m-1)2 m2 < K £ m2 (m+1)2

1

2

3

m

: Sectorial moment of inertia, in cm6, of the ordinary stiffener about its connection with the plating, taken
equal to:h3 t 3for flat bar ordinary stiffeners
I w = w w 10 -6
36
t f b 3f hw2 -6
Iw =10
for "Tee" ordinary stiffeners
12b 3f h w2
Iw =t f b 2f + 2 b f h w + 4 h w2 + 3 t w b f hw 10 - 6 for angles and bulb ordinary stiffeners212(b f + h w )

[ (

Ip

Number of half waves)]: Polar moment of inertia, in cm4, of the ordinary stiffener about its connection with the plating, taken
equal to:h3 t
for flat bar ordinary stiffeners
I t = w w 10 - 4
3
öæ h3 tI p = çç w w + hw2 b f t f 10 - 4
øè 3

for flanged ordinary stiffeners: St Venant's moment of inertia, in cm4, of the ordinary stiffener without face plate, taken equal to:
h t3
for flat bar ordinary stiffeners
I t = w w 10 - 4
3
æt f öù - 41é
ú10
for flanged ordinary stiffeners
I t = êh w t w3 + b f t 3f ç1 - 0.63
ç3ê
b f øú
èëûC : Spring stiffness exerted by the hatch cover top plating, taken equal to:k p E t 3p
C=
10 - 33
æ 1.33 k p h w t p ö
3 s ç1 +ç
1000 s t w3 øè
k p = 1 - h p , to be taken not less than zero; for flanged ordinary stiffeners, kp need not be taken less than 0.1

It

s
s E1
s E1 : As defined in 5.2.3

hp =

tp

: Net thickness, in mm, of the hatch cover plate panel.

5.4
Primary supporting members
5.4.1 Application
The requirements in 5.4.3 to 5.4.5 apply to primary supporting members which may be analysed through isolated
beam models.
Primary supporting members whose arrangement is of a grillage type and which cannot be analysed through isolated
beam models are to be checked by direct calculations, using the checking criteria in 5.4.4.
5.4.2 Minimum net thickness of web
The web net thickness of primary supporting members, in mm, is to be not less than 6mm.
5.4.3 Normal and shear stress for isolated beam
In case that grillage analysis or finite element analysis are not carried out, according to the requirements in 5.1.1, themaximum normal stress s and shear stress t in the primary supporting members are to be obtained, in N/mm2, from thefollowing formulae:－328－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)s ( FS p S + FW pW )l 2m 3
10mW
5s ( FS p S + FW pW )l m
t=
Ash

s=

where:
lm : Span of the primary supporting member.
5.4.4 Checking criteria
The normal stress s and the shear stress t, calculated according to 5.4.3 or determined through a grillage analysis or
finite element analysis, as the case may be, are to comply with the following formulae:
s £sa
t £ta
5.4.5 Deflection limit
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 15 (6) and 16 (5, b))
The net moment of inertia of a primary supporting member, when loaded by sea pressure, is to be such that the
deflection does not exceed ml max , where:m: Coefficient taken equal to:m = 0.0056 for weathertight hatch covers
m = 0.0044 for pontoon hatch covers
l max : Greatest span, in m, of primary supporting members.

5.4.6 Critical buckling stress check of the web panels of the primary supporting members.
The shear stress t in the web panels of the primary supporting members, calculated according to 5.4.3 or determinedthrough a grillage analysis or a finite element analysis, as the case may be, is to comply with the following formula:
0.88t Ct£
S
where:
S :Safety factor defined in Ch 6, Sec 3tC :Critical shear buckling stress, in N/mm2, taken equal to:Rt E £ eH
tC = t E
for
2 3

tC =

R eH æç
ReH ö
13 çè 4 3t E øæ t pr , n öt E = 0.9k t E çç
è 1000d øæaö
k t = 5.35 + 4.0ç
èd ø

for

tE >

ReH
2 3

2

2

Net thickness, in mm, of web of primary supporting member
tpr,n :a :Greater dimension, in m, of web panel of primary supporting memberd :Smaller dimension, in m, of web panel of primary supporting member.
For primary supporting members parallel to the direction of ordinary stiffeners, tC is to be calculated by considering
the actual dimensions of the panels.
For primary supporting members perpendicular to the direction of ordinary stiffeners or for hatch covers built
without ordinary stiffeners, a presumed square panel of dimension d is to be taken for the determination of the stress tC,
where d is the smaller dimension, in m, of web panel of the primary supporting member. In such a case, the average
shear stress t between the values calculated at the ends of this panel is to be considered.
5.4.7
For buckling stiffeners on webs of primary supporting members, the ratio hw tw is to comply with the following
formula:
hw
235
£ 15
tw
ReH

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

5.5
Ordinary stiffeners and primary supporting members of variable cross-section
5.5.1
The net section modulus of ordinary stiffeners and primary supporting members with a variable cross-section is to be
not less than the greater of the value obtained, in cm3, from the following formulae:
w = wCSæ 3.2a - y - 0.8 ö
w = çç1 +wCS
7y + 0.4 øèwhere:Net section modulus, in cm3, for a constant cross-section, complying with the checking criteria in
wCS :
5.4.4
a :
Coefficient taken equal to:
l1
a=
l0

y

:

Coefficient taken equal to:
w1
y=
w0

Length of the variable section part, in m (see Fig. 1)l1 :Span measured, in m, between end supports (see Fig. 1)
l0 :Net section modulus at end, in cm3 (see Fig. 1)
w1 :Net section modulus at mid-span, in cm3 (see Fig. 1).
w0 :Moreover, the net moment of inertia of ordinary stiffeners and primary supporting members with a variablecross-section is to be not less than the greater of the values obtained, in cm4, from the following formulae:
I = I CSé
æ 1 - j öùúII = ê1 + 8a 3 çç 0.2 + 3 j ú CS
ê
è
ø
û
ë
where:Net moment of inertia with a constant cross-section, in cm4, complying with 5.4.5
ICS :
j :
Coefficient taken equal to:
I1
j=
I0
I1 :
Net moment of inertia at end, in cm4 (see Fig. 1)
I0:

Net moment of inertia at mid-span, in cm4 (see Fig. 1).

The use of these formulae is limited to the determination of the strength of ordinary stiffeners and primary supporting
members in which abrupt changes in the cross-section do not occur along their length.
Fig. 1

Variable cross-section stiffener

w1
11

6.

1

w0
10

0

Hatch coamings

6.1
Stiffening
6.1.1
The ordinary stiffeners of the hatch coamings are to be continuous over the breadth and length of the hatch coamings.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

6.1.2
Coamings are to be stiffened on their upper edges with a stiffener suitably shaped to fit the hatch cover closing
appliances.
Moreover, when covers are fitted with tarpaulins, an angle or a bulb section is to be fitted all around coamings ofmore than 3 m in length or 600 mm in height; this stiffener is to be fitted at approximately 250 mm below the upper edge.
The width of the horizontal flange of the angle is not to be less than 180 mm.
6.1.3
Where hatch covers are fitted with tarpaulins, coamings are to be strengthened by brackets or stays with a spacing not
greater than 3 m.
Where the height of the coaming exceeds 900 mm, additional strengthening may be required.
However, reductions may be granted for transverse coamings in protected areas.
6.1.4
When two hatches are close to each other, underdeck stiffeners are to be fitted to connect the longitudinal coamings
with a view to maintaining the continuity of their strength.
Similar stiffening is to be provided over 2 frame spacings at ends of hatches exceeding 9 frame spacings in length.
In some cases, the Society may require the continuity of coamings to be maintained above the deck.
6.1.5
Where watertight metallic hatch covers are fitted, other arrangements of equivalent strength may be adopted.
6.2
Load model
6.2.1
The lateral pressure pC to be considered as acting on the hatch coamings is defined in 6.2.2 and 6.2.3.
6.2.2
The wave lateral pressure pC, in kN/m2, on the No 1 forward transverse hatch coaming is to be taken equal to:・ pC = 220, when a forecastle is fitted in accordance with Sec 1, 7.1
・ pC = 290, in the other cases.
6.2.3
The wave lateral pressure pC, in kN/m2, on the hatch coamings other than the No 1 forward transverse hatch coaming
is to be taken equal to:・ pC = 220
6.2.4
For cargo holds intended for the carriage of liquid cargoes, the liquid internal pressures applied on hatch coaming is
also to be determined according to Ch 4, Sec 6.
6.3
Scantlings
6.3.1 Plating
The net thickness of the hatch coaming plate is to be not less than the greater value obtained, in mm, from thefollowing formulae:t = 15.98s

pC
0.95R eHt = 9.5
6.3.2 Ordinary stiffeners
The net section modulus of the longitudinal or transverse ordinary stiffeners of hatch coamings is to be not less thanthe value obtained, in cm3, from the following formula:p sl 2 10 3
w = 1.21 C
mc p ReH
where:
m : Coefficient taken equal to:m = 16 in generalm = 12 for the end span of stiffeners sniped at the coaming corners
cp : Ratio of the plastic section modulus to the elastic section modulus of the ordinary stiffeners with anattached plate breadth, in mm, equal to 40t, where t is the plate net thickness.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

cp = 1.16 in the absence of more precise evaluation.
6.3.3 Coaming stays
The net section modulus w, in cm3, and the net thickness tw, in mm, of the coaming stays designed as beams withflange connected to the deck or sniped and fitted with a bracket (examples shown in Fig. 2 and Fig. 3) are to be not lessthan the values obtained from the following formulae at the connection with deck:s p H 2 10 3
w= C C C
1.9 R eHtw =s C p C H C 10 3
0.5h ReH

where:
HC :
sC :
h :
Fig. 2

Stay height, in m
Stay spacing, in m
Stay depth, in mm, at the connection with deck.
Fig. 3

Coaming stay: example1

Coaming stay: example 2

For calculating the section modulus of coaming stays, their face plate area may be taken into account only when it iswelded with full penetration welds to the deck plating and adequate underdeck structure is fitted to support the stresses
transmitted by it.
For other designs of coaming stays, such as, for example, those shown in Fig. 4 and Fig. 5, the stress levels
determined through a grillage analysis or finite element analysis, as the case may be, apply and are to be checked at thehighest stressed locations. The stress levels are to comply with the following formulae:s £ 0.95R eHt £ 0.5R eH
Fig. 4

Coaming stay: example 3

Fig. 5－332－

Coaming stay: example 42015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

6.3.4 Local details
The design of local details is to comply with the requirements in this section for the purpose of transferring thepressures on the hatch covers to the hatch coamings and, through them, to the deck structures below.
Hatch coamings and supporting structures are to be adequately stiffened to accommodate the loading from hatch
covers, in longitudinal, transverse and vertical directions.
The normal stress s and the shear stress t, in N/mm2, induced in the underdeck structures by the loads transmitted bystays are to comply with the following formulae:s £ 0.95R eHt £ 0.5R eH
Unless otherwise stated, weld connections and materials are to be dimensioned and selected in accordance with theSociety s requirements.
Double continuous fillet welding is to be adopted for the connections of stay webs with deck plating and the weld
throat thickness is to be not less than 0.44tw, where tw is the gross thickness of the stay web.
Toes of stay webs are to be connected to the deck plating with deep penetration double bevel welds extending over a
distance not less than 15% of the stay width.
6.3.5 Coamings of small hatchways
The gross thickness of coaming plate is to be not less than the lesser of the following values:
・ the gross thickness for the deck inside line of openings calculated for that position, assuming as spacing ofstiffeners the lesser of the values of the height of the coaming and the distance between its stiffeners, if any, or・ 10 mm.
Coamings are to be suitably strengthened where their height exceeds 0.8 m or their greatest horizontal dimension
exceeds 1.2 m, unless their shape ensures an adequate rigidity.
7.

Weathertightness, closing arrangement, securing devices and stoppers

7.1
Weathertightness
7.1.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 16 (1))
Where the hatchway is exposed, the weathertightness is to be ensured by gaskets and clamping devices sufficient in
number and quality.
Weathertightness may also be ensured means of tarpaulins.
7.1.2
In general, a minimum of two securing devices or equivalent is to be provided on each side of the hatch cover.
7.2
Gaskets
7.2.1
The weight of hatch covers and any cargo stowed thereon, together with inertia forces generated by ship motions, areto be transmitted to the ship s structure through steel to steel contact.
This may be achieved by continuous steel to steel contact of the hatch cover skirt plate with the ship s structure or bymeans of defined bearing pads.
7.2.2
The sealing is to be obtained by a continuous gasket of relatively soft elastic material compressed to achieve thenecessary weathertightness. Similar sealing is to be arranged between cross-joint elements.
Where fitted, compression flat bars or angles are to be well rounded where in contact with the gasket and to be madeof a corrosion-resistant material.
7.2.3
The gasket and the securing arrangements are to maintain their efficiency when subjected to large relative
movements between the hatch cover and the ship s structure or between hatch cover elements.
If necessary, suitable devices are to be fitted to limit such movements.
7.2.4
The gasket material is to be of a quality suitable for all environmental conditions likely to be encountered by the ship,
and is to be compatible with the cargoes transported.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

The material and form of gasket selected are to be considered in conjunction with the type of hatch cover, thesecuring arrangement and the expected relative movement between the hatch cover and the ship s structure.
The gasket is to be effectively secured to the hatch cover.
7.2.5
Coamings and steel parts of hatch covers in contact with gaskets are to have no sharp edges.
7.2.6
Metallic contact is required for an earthing connection between the hatch cover and the hull structures. If necessary,
this is to be achieved by means of a special connection for the purpose.
7.3
Closing arrangement, securing devices and stoppers
7.3.1 General
Panel hatch covers are to be secured by appropriate devices (bolts, wedges or similar) suitably spaced alongside thecoamings and between cover elements.
The securing and stop arrangements are to be fitted using appropriate means which cannot be easily removed.
In addition to the requirements above, all hatch covers, and in particular those carrying deck cargo, are to beeffectively secured against horizontal shifting due to the horizontal forces resulting from ship motions.
Towards the ends of the ship, vertical acceleration forces may exceed the gravity force. The resulting lifting forces
are to be considered when dimensioning the securing devices according to 7.3.5 to 7.3.7. Lifting forces from cargo
secured on the hatch cover during rolling are also to be taken into account.
Hatch coamings and supporting structure are to be adequately stiffened to accommodate the loading from hatch
covers.
Hatch covers provided with special sealing devices, insulated hatch covers, flush hatch covers and those havingcoamings of a reduced height (see 2.1) are considered by the Society on a case by case basis.
In the case of hatch covers carrying containers, the scantlings of the closing devices are to take into account thepossible upward vertical forces transmitted by the containers.
7.3.2 Arrangements
The securing and stopping devices are to be arranged so as to ensure sufficient compression on gaskets between
hatch covers and coamings and between adjacent hatch covers.
Arrangement and spacing are to be determined with due attention to the effectiveness for weathertightness,
depending on the type and the size of the hatch cover, as well as on the stiffness of the hatch cover edges between the
securing devices.
At cross-joints of multipanel covers, (male/female) vertical guides are to be fitted to prevent excessive relative
vertical deflections between loaded/unloaded panels.
The location of stoppers is to be compatible with the relative movements between hatch covers and the ship s
structure in order to prevent damage to them. The number of stoppers is to be as small as possible.
7.3.3 Spacing
The spacing of the securing arrangements is to be generally not greater than 6 m.
7.3.4 Construction
Securing arrangements with reduced scantlings may be accepted provided it can be demonstrated that the possibilityof water reaching the deck is negligible.
Securing devices are to be of reliable construction and securely attached to the hatchway coamings, decks or hatch
covers.
Individual securing devices on each hatch cover are to have approximately the same stiffness characteristics.
7.3.5 Area of securing devices
The net cross area of each securing device is to be not less than the value obtained, in cm2, from the following
formula:aæ 235 öA = 1.4S S çç
è ReH øwhere:
Spacing, in m, of securing devices
SS :a :Coefficient taken equal to:－334－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

a = 0.75
a = 1.0

for R eH > 235 N/mm2
for R eH £ 235 N/mm2

In the above calculations, ReH may not be taken greater than 0.7Rm.
Between hatch cover and coaming and at cross-joints, a packing line pressure sufficient to obtain weathertightness is
to be maintained by securing devices. For packing line pressures exceeding 5 N/mm, the net cross area A is to be
increased in direct proportion. The packing line pressure is to be specified.
In the case of securing arrangements which are particularly stressed due to the unusual width of the hatchway, the net
cross area A of the above securing arrangements is to be determined through direct calculations.
7.3.6 Inertia of edges elements
The hatch cover edge stiffness is to be sufficient to maintain adequate sealing pressure between securing devices.
The moment of inertia of edge elements is to be not less than the value obtained, in cm4, from the following formula:= 6 p L S S4
where:
pL : Packing line pressure, in N/mm, to be taken not less than 5
SS : Spacing, in m, of securing devices.
7.3.7 Diameter of rods or bolts
Rods or bolts are to have a gross diameter not less than 19 mm for hatchways exceeding 5 m2 in area.
7.3.8 Stoppers
Hatch covers are to be effectively secured, by means of stoppers, against the transverse forces arising from a pressureof 175 kN/m2.
With the exclusion of No 1 hatch cover, hatch covers are to be effectively secured, by means of stoppers, against thelongitudinal forces acting on the forward end arising from a pressure of 175 kN/m2.
No 1 hatch cover is to be effectively secured, by means of stoppers, against the longitudinal forces acting on theforward end arising from a pressure of 230 kN/m2. This pressure may be reduced to 175 kN/m2 if a forecastle is fitted inaccordance with Sec 1, 7.1.
The equivalent stress in stoppers, their supporting structures and calculated in the throat of the stopper welds is to beequal to or less than the allowable value, equal to 0.8ReH.
7.4
Tarpaulins
7.4.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 15 (11))
Where weathertightness of hatch covers is ensured by means of tarpaulins, at least two layers of tarpaulins are to be
fitted.
Tarpaulins are to be free from jute and waterproof and are to have adequate characteristics of strength and resistanceto atmospheric agents and high and low temperatures.
The mass per unit surface of tarpaulins made of vegetable fibres, before the waterproofing treatment, is to be not lessthan:
・ 0.65 kg/m2 for waterproofing by tarring
・ 0.60 kg/m2 for waterproofing by chemical dressing
・ 0.55 kg/m2 for waterproofing by dressing with black oil.
In addition to tarpaulins made of vegetable fibres, those of synthetic fabrics or plastic laminates may be accepted by
the Society provided their qualities, as regards strength, waterproofing and resistance to high and low temperatures, areequivalent to those of tarpaulins made of vegetable fibres.
7.5
Cleats
7.5.1
Where rod cleats are fitted, resilient washers or cushions are to be incorporated.
7.5.2
Where hydraulic cleating is adopted, a positive means is to be provided to ensure that it remains mechanically lockedin the closed position in the event of failure of the hydraulic system.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

7.6
Wedges
7.6.1 Wedges
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 15 (10))
Wedges are to be of tough wood, generally not more than 200 mm in length and 50 mm in width.
They are generally to be tapered not more than 1 in 6 and their thickness is to be not less than 13 mm.
8.

Drainage

8.1
Arrangement
8.1.1
Drainage is to be arranged inside the line of gaskets by means of a gutter bar or vertical extension of the hatch side
and end coaming.
8.1.2
Drain openings are to be arranged at the ends of drain channels and are to be provided with efficient means forpreventing ingress of water from outside, such as non-return valves or equivalent.
8.1.3
Cross-joints of multi-panel hatch covers are to be arranged with drainage of water from the space above the gasket
and a drainage channel below the gasket.
8.1.4
If a continuous outer steel contact is arranged between the cover and the ship s structure, drainage from the space
between the steel contact and the gasket is also to be provided.
9.

Small hatches fitted on the exposed fore deck

9.1
Application
9.1.1
The requirements of this article apply to steel covers of small hatches fitted on the exposed fore deck over theforward 0.25LCSR-B, where the height of the exposed deck in way of the hatch is less than 0.1LCSR-B or 22 m above thesummer load waterline, whichever is the lesser.
Small hatches are hatches designed for access to spaces below the deck and are capable to be closed weather-tight orwatertight, as applicable. Their opening is generally equal to or less than 2.5 m2.
9.1.2
Small hatches designed for use of emergency escape are to comply with the requirements of this article withexception of 9.4.1 a) and b), 9.4.3 and 9.5.1.
9.2
Strength
9.2.1
For small rectangular steel hatch covers, the gross plate thickness, stiffener arrangement and scantlings are to be notless than those obtained, in mm, from Table 4 and Fig. 6.
Ordinary stiffeners, where fitted, are to be aligned with the metal-to-metal contact points, required in 9.3.1 (see also
Fig. 6).
Primary stiffeners are to be continuous.
All stiffeners are to be welded to the inner edge stiffener (see Fig. 7).

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

Table 4
Nominal size

Gross scantlings for small steel hatch covers on the fore deck
Cover plate thickness

Primary stiffeners

Ordinary stiffeners

(mm

mm)

(mm)

630

630

8

630

830

8

830

630

8

830

830

8

1030

1030

8

120

12 ; 1

80

8;2

1330

1330

8

150

12 ; 2100

10 ; 2

Flat bar (mmmm); number

100

8;1

-

100

8;1

-

100

10 ; 1-

9.2.2
The upper edge of the hatchway coamings is to be suitably reinforced by a horizontal section, generally not morethan 170 to 190 mm from the upper edge of the coamings.
9.2.3
For small hatch covers of circular or similar shape, the cover plate thickness and reinforcement are to comply with
5.2.
9.2.4
For small hatch covers constructed of materials other than steel, the required scantlings are to provide equivalent
strength.
9.3
Weathertightness
9.3.1
The hatch cover is to be fitted with a gasket of elastic material. This is to be designed to allow a metal to metal
contact at a designed compression and to prevent over compression of the gasket by green sea forces that may cause thesecuring devices to be loosened or dislodged. The metal-to-metal contacts are to be arranged close to each securing
device in accordance with Fig. 6 and a sufficient capacity to withstand the bearing force.
9.4
Primary securing devices
9.4.1
Small hatches located on exposed fore deck are to be fitted with primary securing devices such their hatch covers canbe secured in place and weather-tight by means of a mechanism employing any one of the following methods:a) butterfly nuts tightening onto forks (clamps)b) quick acting cleatsc) central locking device.
Dogs (twist tightening handles) with wedges are not acceptable.
9.4.2
The primary securing method is to be designed and manufactured such that the designed compression pressure isachieved by one person without the need of any tools.
9.4.3
For a primary securing method using butterfly nuts, the forks (clamps) are to be of robust design. They are to be
designed to minimize the risk of butterfly nuts being dislodged while in use; by means of curving the forks upward, araised surface on the free end, or a similar method. The plate thickness of unstiffened steel forks is to be not less than 16mm. An example arrangement is shown in Fig. 7.
9.4.4
For small hatch covers located on the exposed deck forward of the fore-most cargo hatch, the hinges are to be fitted
such that the predominant direction of green seas will cause the cover to close, which means that the hinges arenormally to be located on the fore edge.
9.4.5
On small hatches located between the main hatches, for example between Nos. 1 and 2, the hinges are to be placed on
the fore edge or outboard edge, whichever is practicable for protection from green water in beam sea and bow
quartering conditions.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

9.5
Secondary securing devices
9.5.1
Small hatches on the fore deck are to be fitted with an independent secondary securing device e.g. by means of asliding bolt, a hasp or a backing bar of slack fit, which is capable of keeping the hatch cover in place, even in the eventthat the primary securing device became loosened or dislodged. It is to be fitted on the side opposite to the hatch cover
hinges.
Fig.6 

Arrangement of stiffeners                                    

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     !!  2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 5)

Fig. 7

Example of a primary securing method   






 












1) Butterfly nut2) Bolt
3) Pin4) Centre of pin5) Fork (clamp) plate
6) Hatch cover7) Gasket
8) Hatch coaming
9) Bearing pad welded on the bracket of a toggle bolt for metal to metal contact
10) Stiffener11) Inner edge stiffener.

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Section 6

ARRANGEMENT OF HULL AND SUPERSTRUCTURE OPENINGS

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
p : Lateral pressure for glasses, in kN/m2, defined in 3.3.2.

1.

General1.1
Application
1.1.1
The requirements of this Section apply to the arrangement of hull and superstructure openings excluding hatchways,
for which the requirements in Ch 9, Sec 5 apply.
1.2
Definitions
1.2.1 Standard height of superstructure
The standard height of superstructure is that defined in Ch 1, Sec 4.
1.2.2 Standard sheer
The standard sheer is that defined according to the International Load Line Convention, as amended.
1.2.3 Exposed zones
Exposed zones are the boundaries of superstructures or deckhouses set in from the ship s side at a distance equal to orless than 0.04B.
1.2.4 Unexposed zones
Unexposed zones are the boundaries of deckhouses set in from the ship s side at a distance greater than 0.04B.
2.

External openings

2.1
General
2.1.1
Ref. SOLAS Reg.II-1/25-10.1
All external openings leading to compartments assumed intact in the damage analysis, which are below the final
damage waterline, are required to be watertight.
2.1.2
Ref. SOLAS Reg.II-1/25-10.2
External openings required to be watertight in accordance with 2.1.1 are to be of sufficient strength and, except for
cargo hatch covers, are to be fitted with indicators on the bridge.
2.1.3
No openings, be they permanent openings or temporary openings such as shell doors, windows or ports, are allowedon the side shell between the embarkation station of the marine evacuation system and the waterline in the lightest
seagoing condition. Windows and side scuttles of the non-opening type are allowed if the Society s applicable criteria
for fire integrity are complied with.
2.1.4
Ref. SOLAS Reg.II-1/25-10.5
Other closing appliances which are kept permanently closed at sea to ensure the watertight integrity of external
openings are to be provided with a notice affixed to each appliance to the effect that it is to be kept closed. Manholes
fitted with closely bolted covers need not be so marked.

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2.2
Gangway, cargo and coaling ports
2.2.1
Ref. SOLAS Reg.II-1/17-1 & Reg.II-1/17 .10.1 & .10.2 and ILLC, as amended (Resolution MSC.143(77) Reg.
21(2))
Gangway, cargo and coaling ports fitted below the freeboard deck are to be of sufficient strength. They are to beeffectively closed and secured watertight before the ship leaves port, and to be kept closed during navigation.
Such ports are in no case to be so fitted as to have their lowest point below the deepest subdivision load line.
Unless otherwise permitted by the Society, the lower edge of openings is not to be below a line drawn parallel to thefreeboard deck at side, which is at its lowest point at least 230 mm above the upper edge of the uppermost load line.
3.

Side scuttles, windows and skylights

3.1
General3.1.1 Application
The requirements in 3.1 to 3.4 apply to side scuttles and rectangular windows providing light and air, located inpositions which are exposed to the action of sea and/or bad weather.
3.1.2 Side scuttle definition
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(2))
Side scuttles are round or oval openings with an area not exceeding 0.16 m2. Round or oval openings having areas
exceeding 0.16 m2 are to be treated as windows.
3.1.3 Window definition
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(3))
Windows are rectangular openings generally, having a radius at each corner relative to the window size inaccordance with recognised national or international standards, and round or oval openings with an area exceeding 0.16
m2.
3.1.4 Number of openings in the shell plating
Ref. SOLAS Reg.II-1/17-1& Reg.II-1/17.1
The number of openings in the shell plating are to be reduced to the minimum compatible with the design and proper
working of the ship.
3.1.5 Material and scantlings
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(1))
Side scuttles and windows together with their glasses, deadlights and storm covers, if fitted, are to be of approved
design and substantial construction in accordance with, or equivalent to, recognised national or international standards.
Non-metallic frames are not acceptable. The use of ordinary cast iron is prohibited for side scuttles below the
freeboard deck.
3.1.6 Means of closing and opening
Ref. SOLAS Reg.II-1/17-1& Reg.II-1/17.2
The arrangement and efficiency of the means for closing any opening in the shell plating are to be consistent with its
intended purpose and the position in which it is fitted is to be generally to the satisfaction of the Society.
3.1.7 Opening of side scuttles
Ref. SOLAS Reg.II-1/17-1& Reg.II-1/17.3.2
All side scuttles, the sills of which are below the freeboard deck, are to be of such construction as to prevent
effectively any person opening them without the consent of the Master of the ship.
3.2
Opening arrangement
3.2.1 General
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(5))
Side scuttles are not be fitted in such a position that their sills are below a line drawn parallel to the freeboard deck atside and having its lowest point 0.025B or 0.5 m, whichever is the greater distance, above the summer load waterline (ortimber summer load waterline if assigned).

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3.2.2 Side scuttles below (1.4 + 0.025B) m above the water
Ref. SOLAS Reg.II-1/17-1& Reg.II-1/17 .3.3.1 and .3.3.3
Where in tween decks the sills of any of the side scuttles are below a line drawn parallel to the freeboard deck at sideand having its lowest point 1.4+0.025B m above the water when the ship departs from any port, all the side scuttles inthat tween decks are to be closed watertight and locked before the ship leaves port, and they may not be opened before
the ship arrives at the next port. In the application of this requirement, the appropriate allowance for fresh water may bemade when applicable.
For any ship that has one or more side scuttles so placed that the above requirements apply when it is floating at its
deepest subdivision load line, the Society may indicate the limiting mean draught at which these side scuttles are tohave their sills above the line drawn parallel to the freeboard deck at side, and having its lowest point 1.4+0.025B above
the waterline corresponding to the limiting mean draught, and at which it is therefore permissible to depart from port
without previously closing and locking them and to open them at sea under the responsibility of the Master during thevoyage to the next port. In tropical zones as defined in the International Convention on Load Lines in force, thislimiting draught may be increased by 0.3 m.
3.2.3 Cargo spaces
Ref. SOLAS Reg.II-1/17-1& Reg.II-1/17.6.1 to .6.3
No side scuttles may be fitted in any spaces which are appropriated exclusively for the carriage of cargo or coal.
Side scuttles may, however, be fitted in spaces appropriated alternatively for the carriage of cargo or passengers, butthey are to be of such construction as to prevent effectively any person opening them or their deadlights without theconsent of the Master.
If cargo is carried in such spaces, the side scuttles and their deadlights are to be closed watertight and locked before
the cargo is shipped. The Society, at its discretion, may prescribe that the time of closing and locking is to be recorded
in a log book.
3.2.4 Non-opening type side scuttles
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(6))
Side scuttles are to be of the non-opening type where they become immersed by any intermediate stage of flooding or
the final equilibrium waterline in any required damage case for ships subject to damage stability regulations.
3.2.5 Manholes and flush scuttles
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 18(1))
Manholes and flush scuttles in positions 1 or 2, or within superstructures other than enclosed superstructures, are to
be closed by substantial covers capable of being made watertight. Unless secured by closely spaced bolts, the covers areto be permanently attached.
3.2.6 Automatic ventilating scuttles
Ref. SOLAS Reg.II-1/17-1& Reg.II-1/17.7
Automatic ventilating side scuttles, fitted in the shell plating below the freeboard deck, are considered by the Society
on a case by case basis.
3.2.7 Window arrangement
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(7))
Windows are not to be fitted below the freeboard deck, in first tier end bulkheads or sides of enclosed superstructuresand in first tier deckhouses considered buoyant in the stability calculations or protecting openings leading below.
3.2.8 Skylights
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(12))
Fixed or opening skylights are to have glass thickness appropriate to their size and position as required for side
scuttles and windows. Skylight glasses in any position are to be protected from mechanical damage and, where fitted inpositions 1 or 2, to be provided with permanently attached robust deadlights or storm covers.
3.3
Glasses
3.3.1 GeneralIn general, toughened glasses with frames of special type are to be used in compliance with, or equivalent to,recognised national or international standards. The use of clear plate glasses is considered by the Society on a case bycase basis.

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3.3.2 Design loads
The design load is to be determined in accordance with the applicable requirements of Ch 9, Sec 4.
3.3.3 Materials
Toughened glasses are to be in accordance with ISO 1095 for side scuttles and ISO 3254 for windows.
3.3.4 Thickness of toughened glasses in side scuttles
The thickness of toughened glasses in side scuttles is to be not less than that obtained, in mm, from the following
formula:dt=p358
where:
d : Side scuttle diameter, in mm.
3.3.5 Thickness of toughened glasses in rectangular windows
The thickness of toughened glasses in rectangular windows is to be not less than that obtained, in mm, from thefollowing formula:
b
t=
bp
200
where:b : Coefficient defined in Table 1. b is to be obtained by linear interpolation for intermediate values of a/b
a : Length, in mm, of the longer side of the windowb : Length, in mm, of the shorter side of the window.
Table 1

Coefficient b

a/b

b

1.0

0.284

1.5

0.475

2.0

0.608

2.5

0.684

3.0

0.716

3.5

0.734

³ 4.0

0.750

The Society may require both limitations on the size of rectangular windows and the use of glasses of increased
thickness in way of front bulkheads which are particularly exposed to heavy sea.
3.4
Deadlight arrangement
3.4.1 General
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 23(4))
Side scuttles to the following spaces are to be fitted with hinged inside deadlights:
・ spaces below freeboard deck・ spaces within the first tier of enclosed superstructures
・ first tier deckhouses on the freeboard deck protecting openings leading below or considered buoyant in stability
calculations.
Deadlights are to be capable of being closed and secured watertight if fitted below the freeboard deck andweathertight if fitted above.
3.4.2 Openings at the side shell in the second tierRef. ILLC, as amended (Resolution MSC.143(77) Reg. 23(8))
Side scuttles and windows at the side shell in the second tier are to be provided with efficient, hinged inside
deadlights capable of being closed and secured weathertight, if the superstructure protects direct access to an opening
leading below or is considered buoyant in the stability calculations.

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3.4.3 Openings set inboard in the second tierRef. ILLC, as amended (Resolution MSC.143(77) Reg. 23(9) and .23(10))
Side scuttles and windows in side bulkheads set inboard from the side shell in the second tier which protect directaccess below to spaces listed in 3.4.1, are to be provided with either hinged inside deadlights or, where they areaccessible, permanently attached external storm covers of approved design and substantial construction capable ofbeing closed and secured weathertight.
Cabin bulkheads and doors in the second tier and above separating side scuttles and windows from a direct accessleading below or the second tier considered buoyant in the stability calculations may be accepted in place of deadlights
or storm covers fitted to the side scuttles and windows.
Note 1: Deadlights in accordance with recognised standards are fitted to the inside of windows and side scuttles,
while storm covers of comparable specifications to deadlights are fitted to the outside of windows, where
accessible, and may be hinged or portable.
3.4.4 Deckhouses on superstructures of less than standard heightRef. ILLC, as amended (Resolution MSC.143(77) Reg. 23(11))
Deckhouses situated on a raised quarter deck or on the deck of a superstructure of less than standard height may be
regarded as being in the second tier as far as the requirements for deadlights are concerned, provided the height of theraised quarterdeck or superstructure is equal to or greater than the standard quarter deck height.
3.4.5 Openings protected by a deckhouse
Where an opening in a superstructure deck or in the top of a deckhouse on the freeboard deck which gives access toa space below the freeboard deck or to a space within an enclosed superstructure is protected by a deckhouse, then it isconsidered that only those side scuttles fitted in spaces which give direct access to an open stairway need to be fittedwith deadlights.
4.

Discharges

4.1
Arrangement of discharges
4.1.1 Inlets and discharges
Ref. SOLAS Reg.II-1/17-1 & Reg.II-1/17.9.1
All inlets and discharges in the shell plating are to be fitted with efficient and accessible arrangements for preventing
the accidental admission of water into the ship.
4.1.2 Inboard opening of ash-shoot, rubbish-shoot, etc.
Ref. SOLAS Reg.II-1/17-1 & Reg.II-1/17 .11.1 and .11.2
The inboard opening of each ash-shoot, rubbish-shoot, etc. is to be fitted with an efficient cover.
If the inboard opening is situated below the freeboard deck, the cover is to be watertight, and in addition an automatic
non-return valve is to be fitted in the shoot in an easily accessible position above the deepest subdivision load line.
When the shoot is not in use, both the cover and the valve are to be kept closed and secured.
4.2
Arrangement of garbage chutes
4.2.1 Inboard end above the waterline
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 22-1(1, b))
The inboard end is to be located above the waterline formed by an 8.5 heel, to port or starboard, at a draft
corresponding to the assigned summer freeboard, but not less than 1000 mm above the summer load waterline.
Where the inboard end of the garbage chute exceeds 0.01LLL above the summer load waterline, valve control fromthe freeboard deck is not required, provided the inboard gate valve is always accessible under service conditions.
4.2.2 Inboard end below the waterline
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 22-1(4))
Where the inboard end of a garbage chute is below the waterline corresponding to the deepest draught after damage
in a ship of more than 100 m in length, then:・ the inboard end hinged cover/valve is to be watertight・ the valve is to be a screw-down non-return valve fitted in an easily accessible position above the deepest
subdivision load line
・ the screw-down non-return valve is to be controlled from a position above the freeboard deck and provided with
open/shut indicators. The valve control is to be clearly marked: «Keep closed when not in use».
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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 6)

4.2.3 Gate valves
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 22-1(1, a))
For garbage chutes, two gate valves controlled from the working deck of the chute may be accepted instead of a
non-return valve with a positive means of closing it from a position above the freeboard deck. In addition, the lower
gate valve is to be controlled from a position above the freeboard deck. An interlock system between the two valves is
to be arranged.
The distance between the two gate valves is to be adequate to allow the smooth operation of the interlock system.
4.2.4 Hinged cover and discharge flap
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 22-1(1, c))
The upper and lower gate valves, as required in 4.2.3, may be replaced by a hinged weathertight cover at the inboard
end of the chute together with a discharge flap.
The cover and discharge flap are to be arranged with an interlock so that the flap cannot be operated until the hopper
cover is closed.
4.2.5 Marking of valve and hinged coverRef. ILLC, as amended (Resolution MSC.143(77) Reg. 22-1(3))
The controls for the gate valves and/or hinged covers are to be clearly marked: «Keep closed when not in use».
4.3
Scantlings of garbage chutes
4.3.1 Material
The chute is to be constructed of steel. Other equivalent materials are considered by the Society on a case by casebasis.
4.3.2 Wall thickness
The wall thickness of the chute up to and including the cover is to be not less than that obtained, in mm, from Table
2.
Table 25.

Wall thickness of garbage chutes

External diameter d, in mm

Thickness, in mm

d £ 807.0

80 < d < 180

7.0 + 0.03(d - 80)

180 £ d £ 220

10.0 + 0.063(d - 180)d > 220

12.5

Freeing ports

5.1
General provisions
5.1.1 General
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (1, a) and Reg.3 (15))
Where bulwarks on the weather portions of freeboard or superstructure decks form wells, ample provision is to bemade for rapidly freeing the decks of water and for draining them.
A well is any area on the deck exposed to the weather, where water may be entrapped. Wells are considered to be
deck areas bounded on four sides by deck structures; however, depending on their configuration, deck areas boundedon three or even two sides by deck structures may be deemed wells.
5.1.2 Freeing port areas
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24)
The minimum required freeing port areas in bulwarks on the freeboard deck are specified in Table 3.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 6)

Table 3Freeing port area in bulwark located on freeboard deck
Area A of freeing ports, in m2

Applicable requirement

Type B-100

0.33lB hB

5.5.2

Type B-60

0.25lB hB

5.5.1

0.33lB hB

5.3.1

A2

5.3.1

A3

5.3.2

AS for superstructures

5.4.2

AW for wells

5.4.3

A1

5.2.1

Ship types or ship particulars

Ships fitted with a trunk included in freeboard
calculation and/ or breadth ³ 0.6B
Ships fitted with a trunk not included in freeboard
calculation and/or continuous or substantiallycontinuous hatch coamings
Ships fitted with non-continuous trunk and/ or
hatch coamings
Ships fitted with open superstructure
Other ships
where:

lB : Length, in m, of bulwark in a well at one side of the shiphB : Mean height, in m, of bulwark in a well of length lB.

5.1.3 Freeing port arrangement
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (5))
Where a sheer is provided, two thirds of the freeing port area required is to be provided in the half of the well nearer
the lowest point of the sheer curve.
One third of the freeing port area required is to be evenly spread along the remaining length of the well. With zero or
little sheer on the exposed freeboard deck or an exposed superstructure deck the freeing port area is to be evenly spreadalong the length of the well.
However, bulwarks may not have substantial openings or accesses near the breaks of superstructures, unless they are
effectively detached from the superstructure sides.
5.1.4 Freeing port positioning
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (5) and 24 (6))
The lower edge of freeing ports is to be as near the deck as practicable.
All the openings in the bulwark are to be protected by rails or bars spaced approximately 230 mm apart.
5.1.5 Freeing port closures
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (6))
If shutters or closures are fitted to freeing ports, ample clearance is to be provided to prevent jamming. Hinges are tohave pins or bearings of non-corrodible material. If shutters are fitted with securing appliances, these appliances are to
be of approved construction.
5.2
Freeing port area in a well not adjacent to a trunk or hatchways
5.2.1 Freeing port area
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (1, b and c))
Where the sheer in way of the well is standard or greater than the standard, the freeing port area on each side of theship for each well is to be not less than that obtained, in m2, in Table 4.
In ships with no sheer, the above area is to be increased by 50%. Where the sheer is less than the standard, thepercentage of increase is to be obtained by linear interpolation.

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Table 4

Freeing port area in a well not adjacent to a trunk or hatchways
Area A1 of freeing ports, in m2

Location
Freeboard deck and raisedquarterdecks
Superstructure deckslB £ 20

lB > 20

0.7 + 0.035lB + AC

0.07lB + AC

0.35 + 0.0175lB + 0.5AC

0.035lB + 0.5AC

where:
lB : Length, in m, of bulwark in the well, but need in no case to be taken as greater than 0.7LLL
A: Area, in m2, to be taken, with its sign, equal to:l
AC = B (hB - 1.2) for hB > 1.2
25
AC = 0
for 0.9 £ hB £ 1.2
lB
AC =(hB - 0.9) for hB < 0.9
25hB : Mean height, in m, of the bulwark in a well of length lB.

5.2.2 Minimum freeing port area for a deckhouse having breadth not less than 0.8B
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (1, d))Where a flush deck ship is fitted amidships with a deckhouse having breadth not less than 0.8B and the width of thepassageways along the side of the ship less than 1.5 m, the freeing port area is to be calculated for two separate wells,
before and abaft the deckhouse. For each of these wells, the freeing port area is to be obtained from Table 4, where lB is
to be taken equal to the actual length of the well considered.
5.2.3 Minimum freeing port area for screen bulkhead
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (1, e))Where a screen bulkhead is fitted across the full breadth of the ship at the fore end of a midship deckhouse, theweather deck is to be considered as divided into two wells, irrespective of the width of the deckhouse, and the freeing
port area is to be obtained in accordance with 5.1.2.
5.3
Freeing port area in a well contiguous to a trunk or hatchways
5.3.1 Freeing area for continuous trunk or continuous hatchway coaming
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (2))
Where the ship is fitted with a continuous trunk not included in the calculation of freeboard or where continuous or
substantially continuous hatchway side coamings are fitted between detached superstructures, the freeing port area is tobe not less than that obtained, in m2, from Table 5.
Table 5Freeing port area in a well contiguous to a continuous trunk or hatchway

Breadth BH , in m, of hatchway or trunk

Area A2 of freeing ports, in m2

BH £ 0.4B

0.2lB hB

0.4B < BH < 0.75B

é
æ BH
öù
- 0.4 úl BhB
ê0.2 - 0.286ç
è B
øû
ë

BH ³ 0.75B

0.1lB hB

where:
lB : Length, in m, of bulwark in a well at one side of the shiphB : Mean height, in m, of bulwark in a well of length lB.

Where the ship is fitted with a continuous trunk having breadth not less than 0.6B, included in the calculation of
freeboard, and where open rails on the weather parts of the freeboard deck in way of the trunk for at least half the lengthof these exposed parts are not fitted, the freeing port area in the well contiguous to the trunk is to be not less than 33%
of the total area of the bulwarks.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 6)

5.3.2 Freeing area for non-continuous trunk or hatchway coaming
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (3))
Where the free flow of water across the deck of the ship is impeded due to the presence of a non-continuous trunk,
hatchway coaming or deckhouse in the whole length of the well considered, the freeing port area in the bulwark of thiswell is to be not less than that obtained, in m2, from Table 6.
Table 6

Freeing port area in a well contiguous to a non-continuous trunk or hatchway
Free flow area fP , in m2

Freeing port area A3, in m2

f P £ A1

A2

A1< f P < A2

A1+ A2 - f P

f P ³ A2

A1

where:
fP: Free flow area on deck, equal to the net area of gaps between hatchways, and between
hatchways and superstructures and deckhouses up to the actual height of the bulwark

A1 : Area of freeing ports, in m2, to be obtained from Table 4
A2 : Area of freeing ports, in m2, to be obtained from Table 5.

5.4
Freeing port area in an open space within superstructures
5.4.1 General
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (4))
In ships having superstructures on the freeboard or superstructure decks, which are open at either or both ends towells formed by bulwarks on the open decks, adequate provision for freeing the open spaces within the superstructures
is to be provided.
5.4.2 Freeing port area for open superstructures
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (4))
The freeing port area on each side of the ship for the open superstructure is to be not less than that obtained, in m2,
from the following formula:é æ l ö 2 ùæ b h ö
AS = A1C SH ê1 - çç W úçç 0 s
êë è l T ø úûè 2l T hW ø
where:
lT : Total well length, in m, to be taken equal to:
lT = lW + l S
lW : Length, in m, of the open deck enclosed by bulwarks
lS : Length, in m, of the common space within the open superstructures
A1 : Freeing port area, in m2, required for an open well of length lT, in accordance with Table 4, where AC is
to be taken equal to zero
CSH : Coefficient which accounts for the absence of sheer, if applicable, to be taken equal to:in the case of standard sheer or sheer greater than standard sheer
CSH = 1.0
in the case of no sheer
CSH = 1.5
b0 : Breadth, in m, of the openings in the end bulkhead of enclosed superstructures
hS : Standard superstructure height, in m, defined in 1.2.1
hW : Distance, in m, of the well deck above the freeboard deck.
5.4.3 Freeing port area for open wellRef. ILLC, as amended (Resolution MSC.143(77) Reg. 24 (4))
The freeing port area on each side of the ship for the open well is to be not less than that obtained, in m2, from thefollowing formula:æ h öAW = A1c SH çç S
è 2hW øA1 : Freeing port area, in m2, required for an open well of length lW, in accordance with Table 4－348－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 6)

cSH, hS, hW, lW : Defined in 5.4.2.
The resulting freeing port areas for the open superstructure AS and for the open well AW are to be provided alongeach side of the open space covered by the open superstructure and each side of the open well, respectively.
5.5
Freeing port area in bulwarks of the freeboard deck for ships of types B-100 and B-60
5.5.1 Freeing arrangement for type B-60
For type B-60 ships, the freeing port area in the lower part of the bulwarks of the freeboard deck is to be not less than
25% of the total area of the bulwarks in the well considered.
The upper edge of the sheer strake is to be kept as low as possible.
5.5.2 Freeing arrangement for type B-100 ships with trunks
For type B-100 ships, open rails are to be fitted on the weather parts of the freeboard deck in way of the trunk for atleast half the length of these exposed parts.
Alternatively, if a continuous bulwark is fitted, the freeing port area in the lower part of the bulwarks of the freeboard
deck is to be not less than 33% of the total area of the bulwarks in the well considered.
6.

Machinery space openings

6.1
Engine room skylights
6.1.1
Engine room skylights in positions 1 or 2 are to be properly framed, securely attached to the deck and efficiently
enclosed by steel casings of suitable strength. Where the casings are not protected by other structures, their strength will
be considered by the Society on a case by case basis.
6.2
Closing devices
6.2.1 Machinery casings
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 17 (1)and 12 (1))
Openings in machinery space casings in positions 1 or 2 are to be fitted with doors of steel or other equivalentmaterials, permanently and strongly attached to the bulkhead, and framed, stiffened and fitted so that the whole
structure is of equivalent strength to the unpierced bulkhead and weathertight when closed. The doors are to be capableof being operated from both sides and generally to open outwards to give additional protection against wave impact.
Other openings in such casings are to be fitted with equivalent covers, permanently attached in their proper position.
6.2.2 Height of the sill of the door
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 17 (1 and 2))
The height of the sill of the door is to be not less than:・ 600 mm above the deck if in position 1
・ 380 mm above the deck if in position 2・ 230 mm in all other cases.
6.2.3 Double doors
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 17 (1 and 2))
Where casings are not protected by other structures, double doors (i.e. inner and outer doors) are required for ships
assigned freeboard less than that based on Table B of the International Load Line Convention, as amended. An innersill of 230 mm in conjunction with the outer sill of 600 mm is to be provided.
6.2.4 Fiddly openings
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 17 (5))
Fiddly openings are to be fitted with strong covers of steel or other equivalent material permanently attached in theirproper positions and capable of being secured weathertight.
6.3
Coamings
6.3.1
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 17 (3))
Coamings of any fiddly, funnel or machinery space ventilator in an exposed position on the freeboard deck orsuperstructure deck are to be as high above the deck as is reasonable and practicable.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 6)

In general, ventilators necessary to continuously supply the machinery space and, on demand, the emergency
generator room are to have coamings whose height is in compliance with 8.1.3, but need not be fitted with weathertightclosing appliances.
6.3.2
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 17 (4))
Where, due to the ship s size and arrangement, this is not practicable, lesser heights for machinery space andemergency generator room ventilator coamings, fitted with weathertight closing appliances in accordance with 8.1.2,
may be permitted by the Society in combination with other suitable arrangements to ensure an uninterrupted, adequate
supply of ventilation to these spaces.
7.

Companionway

7.1
General7.1.1 Openings in freeboard deck
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 18 (2))
Openings in freeboard deck other than hatchways, machinery space openings, manholes and flush scuttles are to beprotected by an enclosed superstructure or by a deckhouse or companionway of equivalent strength andweathertightness.
7.1.2 Openings in superstructures
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 18 (2))
Openings in an exposed superstructure deck or in the top of a deckhouse on the freeboard deck which give access toa space below the freeboard deck or a space within an enclosed superstructure are to be protected by an efficient
deckhouse or companionway.
7.1.3 Openings in superstructures having height less than standard heightRef. ILLC, as amended (Resolution MSC.143(77) Reg. 18 (3))
Openings in the top of a deckhouse on a raised quarterdeck or superstructure of less than standard height, having aheight equal to or greater than the standard quarterdeck height are to be provided with an acceptable means of closing
but need not be protected by an efficient deckhouse or companionway provided the height of the deckhouse is at least
the height of the superstructure. Openings in the top of the deckhouse on a deckhouse of less than a standard
superstructure height may be treated in a similar manner.
7.2
Scantlings
7.2.1
Companionways on exposed decks protecting openings leading into enclosed spaces are to be of steel and strongly
attached to the deck and are to have adequate scantlings.
7.3
Closing devices
7.3.1 Doors
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 18 (2))
Doorways in deckhouses or companionways leading to or giving access to spaces below the freeboard deck or to
enclosed superstructures are to be fitted with weathertight doors. The doors are to be made of steel, to be capable ofbeing operated from both sides and generally to open outwards to give additional protection against wave impact.
Alternatively, if stairways within a deckhouse are enclosed within properly constructed companionways fitted withweathertight doors, the external door need not be weathertight.
Where the closing appliances of access openings in superstructures and deckhouses are not weathertight, interior
deck openings are to be considered exposed, i.e. situated in the open deck.
7.3.2 Height of sills
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 18 (4 to 6))
The height above the deck of sills to the doorways in companionways is to be not less than:・ 600 mm in position 1
・ 380 mm in position 2.
Where access is provided from the deck above as an alternative to access from the freeboard deck, the height of thesills into the bridge or poop is to be 380 mm. This also applies to deckhouses on the freeboard deck.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 6)

Where access is not provided from above, the height of the sills to doorways in deckhouses on the freeboard deck is
to be 600 mm.
8.

Ventilators

8.1
Closing appliances
8.1.1 General
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 19 (4))
Ventilator openings are to be provided with efficient weathertight closing appliances of steel or other equivalentmaterial.
8.1.2 Closing appliance exemption
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 19 (3))
Ventilators need not be fitted with closing appliances, unless specifically required by the Society, if the coamings
extend for more than:・ 4.5 m above the deck in position 1・ 2.3 m above the deck in position 2.
8.1.3 Closing appliances for ships of not more than 100 m in length
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 19 (4))
In ships of not more than 100 m in length, the closing appliances are to be permanently attached to the ventilator
coamings.
8.1.4 Closing appliances for ships of more than 100 m in length
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 19 (4))
Where, in ships of more than 100 m in length, the closing appliances are not permanently attached, they are to beconveniently stowed near the ventilators to which they are to be fitted.
8.1.5 Ventilation of machinery spaces and emergency generator room
In order to satisfactorily ensure, in all weather conditions:・ the continuous ventilation of machinery spaces,
・ and, when necessary, the immediate ventilation of the emergency generator room,the ventilators serving such spaces are to comply with 8.1.2, i.e. their openings are to be so located that they do not
require closing appliances.
8.1.6 Reduced height of ventilator coamings for machinery spaces and emergency generator room
Where, due to the ship s size and arrangement, the requirements in 8.1.5 are not practicable, lesser heights may be
accepted for machinery space and emergency generator room ventilator coamings fitted with weathertight closing
appliances in accordance with 8.1.1, 8.1.3 and 8.1.4 in combination with other suitable arrangements, such as
separators fitted with drains, to ensure an uninterrupted, adequate supply of ventilation to these spaces.
8.1.7 Closing arrangements of ventilators led overboard or through enclosed superstructures
Closing arrangements of ventilators led overboard to the ship side or through enclosed superstructures are consideredby the Society on a case by case basis. If such ventilators are led overboard more than 4.5 m above the freeboard deck,
closing appliances may be omitted provided that satisfactory baffles and drainage arrangements are fitted.
8.2
Coamings
8.2.1 General
Ref. ILLC, as amended (Resolution MSC.143(77) Reg. 19 (1 and 2))
Ventilators in positions 1 or 2 to spaces below freeboard decks or decks of enclosed superstructures are to havecoamings of steel or other equivalent material, substantially constructed and efficiently connected to the deck.
Ventilators passing through superstructures other than enclosed superstructures are to have substantially constructedcoamings of steel or other equivalent material at the freeboard deck.
8.2.2 Scantlings
The scantlings of ventilator coamings exposed to the weather are to be not less than those obtained from Table 7.
In exposed locations or for the purpose of compliance with buoyancy calculations, the height of coamings may berequired to be increased to the satisfaction of the Society.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 9 Section 6)

Table 7

Scantlings of ventilator coamings

FeatureScantlings

Height of the coaming, in mm, above theh = 900 in position 1

deck

h = 760 in position 2

Thickness of the coaming, in mm(1)Supportt = 5.5 + 0.01 dVwith 7.5 £ t £ 10
If h > 900 mm, the coaming is to be suitably stiffenedor supported by stays.

where:
dV : External diameter of the ventilator, in mm.
(1) Where the height of the ventilator exceeds the height h, the thickness of the coaming may be
gradually reduced, above that height, to a minimum of 6.5 mm.

9.

Tank cleaning openings

9.1
General9.1.1
Ullage plugs, sighting ports and tank cleaning openings may not be arranged in enclosed spaces.

－352－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Chapter 10
Section 1

HULL OUTFITTINGRUDDER AND MANOEUVRING ARRANGEMENT

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
CR : Rudder force, in N
QR : Rudder torque, in N-m
A : Total movable area of the rudder, in m2, measured at the mid-plane of the rudder
For nozzle rudders, A is not to be taken less than 1.35 times the projected area of the nozzle.
At : Area equal to A + area of a rudder horn, if any, in m2
Af : Portion of rudder area located ahead of the rudder stock axis, in m2
b : Mean height of rudder area, in m
c : Mean breadth of rudder area, in m, see Fig. 1
L : Aspect ratio of rudder area At, taken equal to:b2
L=AtV0 : Maximum ahead speed, in knots, as defined in Ch 1, Sec 4. If this speed is less than 10, V0 is to be replaced by:(V + 20)
V min = 0
3
Va : Maximum astern speed, in knots, to be taken not less than 0.5V0. For greater astern speeds special evaluation of
rudder force and torque as a function of the rudder angle may be required. If no limitations for the rudder angle atastern condition is stipulated, the factor k 2 is not to be taken less than given in Table 1 for astern condition.
Fig. 1

Dimensions of rudder
x2
c

b

A

Af
x1
c=

1.

x1 + x22

b= AcGeneral1.1
Manoeuvring arrangement
1.1.1
The manoeuvring arrangement includes all parts from the rudder and steering gear to the steering position necessary
for steering the ship.
1.1.2
Rudder stock, rudder coupling, rudder bearings and the rudder body are dealt with in this Section. The steering gearis to comply with the provisions of Part D.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

1.1.3
The steering gear compartment shall be readily accessible and, as far as practicable, separated from the machinery
space.
Note : Concerning the use of non-magnetisable material in the wheel house in way of a magnetic compass, therequirements of the national Administration concerned are to be observed.
1.2
Structural details
1.2.1
Effective means are to be provided for supporting the weight of the rudder body without excessive bearing pressure,e.g. by a rudder carrier attached to the upper part of the rudder stock. The hull structure in way of the rudder carrier is tobe suitably strengthened.
1.2.2
Suitable arrangements are to be provided to prevent the rudder from lifting.
1.2.3
Connections of rudder blade structure with solid parts in forged or cast steel, which are used as rudder stock housing,are to be suitably designed to avoid any excessive stress concentration at these areas.
1.2.4
The rudder stock is to be carried through the hull either enclosed in a watertight trunk, or glands are to be fitted above
the deepest load waterline, to prevent water from entering the steering gear compartment and the lubricant from being
washed away from the rudder carrier. If the top of the rudder trunk is below the deepest waterline two separate stuffing
boxes are to be provided.
1.3(void)

1.4
Materials
1.4.1
For materials for rudder stock, pintles, coupling bolts etc. refer to Part K.
1.4.2
In general, materials having ReH of less than 200 N/mm2 and Rm of less than 400 N/mm2 or more than 900 N/mm2 are
not to be used for rudder stocks, pintles, keys and bolts. The requirements of this Section are based on a with ReH of
235 N/mm2. If material is used having a ReH differing from 235 N/mm2, the material factor kr is to be determined asfollows:
æ 235 ök r = çç
è ReH ø
235
kr =
ReH

0.75

for ReH > 235
for R eH £ 235

where:
ReH : Minimum yield stress of material used, in N/mm2. ReH is not to be taken greater than 0.7Rm or 450 N/mm2,
whichever is less.
1.4.3
Before significant reductions in rudder stock diameter due to the application of steels with ReH exceeding 235 N/mm2
are accepted, the Society may require the evaluation of the elastic rudder stock deflections. Large deflections should be
avoided in order to avoid excessive edge pressures in way of bearings.
1.4.4
The permissible stresses given in 5.1 are applicable for normal strength steel. When higher strength steels are used,higher values may be used for the permissible stresses, on a case by case basis.
2.

Rudder force and torque2.1
Rudder force and torque for normal rudders
2.1.1
The rudder force is to be determined, in N, according to the following formula:
C R = 132 AV 2 k 1 k 2 k 3 k t－354－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

where:
V : V0 for ahead condition
Va for astern condition
k1 : Coefficient, depending on the aspect ratio L , taken equal to:
k1 = (L + 2 ) / 3 , where L need not be taken greater than 2
k 2 : Coefficient, depending on the type of the rudder and the rudder profile according to Table 1
Table 1

Coefficient k 2
k2

Profile /type of rudder

Ahead

AsternNACA-00 series Göttingen profiles

1.10

0.80

Flat side profiles

1.10

0.90

Mixed profiles (e. g. HSVA)

1.21

0.90

Hollow profiles

1.35

0.90
to be specially considered;High lift rudders

1.70

Fish tail

1.40

0.80

Single plate

1.00

1.00

if not known: 1.30

k 3 : Coefficient, depending on the location of the rudder, taken equal to:k 3 = 0.80 for rudders outside the propeller jet
k 3 = 1.00 elsewhere, including also rudders within the propeller jet
k 3 = 1.15 for rudders aft of the propeller nozzle
k t : Coefficient equal to 1.0 for rudders behind propeller. Where a thrust coefficient C Th > 1.0 , the Society
may consider a coefficient k t different from 1.0, on a case by case basis.
2.1.2
The rudder torque, in Nm, is to be determined by the following formula:
QR = C R r
where:
r : Lever of the force CR, in m, taken equal to:r = c(a - k bc ) , without being less than 0.1c for ahead conditiona : Coefficient taken equal to:a = 0.33
for ahead conditiona = 0.66
for astern condition (general)a = 0.75
for astern condition (hollow profiles)
For parts of a rudder behind a fixed structure such as a rudder horn:a = 0.25
for ahead conditiona = 0.55
for astern condition
For high lift rudders a is to be specially considered. If not known, a = 0.40 may be used for the ahead condition
kbc : Balance factor as follows:
k bc =

AfA
k bc = 0.08 for unbalanced rudders

2.1.3
Effects of the provided type of rudder/profile on choice and operation of the steering gear are to be observed.
2.2
Rudder force and torque for rudder blades with cut-outs (semi-spade rudders)
2.2.1
The total rudder force C R is to be calculated according to 2.1.1. The pressure distribution over the rudder area, uponwhich the determination of rudder torque and rudder blade strength are to be based, is to be obtained as follows:－355－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

・ the rudder area may be divided into two rectangular or trapezoidal parts with areas A1 and A2 , see Fig. 2.
・ the resulting force, in N, of each part may be taken as:
A
CR1 = C R 1
AACR 2 = CR 2
A
2.2.2
The resulting torque, in N-m, of each part is to be taken as:
Q R1 = C R1 r1
Q R 2 = C R 2 r2
where:
r1 = c1 (a - k b1 ) , in m
r2 = c 2 (a - k b 2 ) , in m
A1 f
k b1 =
A1
A2 f
kb2 =
A2
A1 f , A2 f : As defined in Fig. 2

c1 =

A1
b1

c2 =

A2
b2

b1, b2: Mean heights of the partial rudder areas A1 and A2 (see Fig. 2).
Fig. 2

Areas A1 and A2
c1

b1

A1

b2

A1f

A2

A2f

c2

2.2.3
The total rudder torque, in N-m, is to be determined according to the following formulae:
Q R = Q R1 + Q R 2 , without being less than Q R min = C R r1, 2 min
where:
r1, 2 min =3.

0.1(c1 A1 + c 2 A2 ) , in m.
A

Scantlings of the rudder stock

3.1
Rudder stock diameter
3.1.1
The diameter of the rudder stock, in mm, for transmitting the rudder torque is not to be less than:－356－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Dt = 4.2 3 Q R k r

where:QR : As defined in 2.1.2, 2.2.2 and 2.2.3
The related torsional stress, in N/mm2, is:
68
tt =
kr
where:
kr : As defined in 1.4.2 and 1.4.3.
3.1.2
The diameter of the rudder stock determined according to 3.1.1 is decisive for the steering gear, the stopper and thelocking device.
3.1.3
In case of mechanical steering gear the diameter of the rudder stock in its upper part which is only intended fortransmission of the torsional moment from the auxiliary steering gear may be 0.9Dt. The length of the edge of thequadrangle for the auxiliary tiller must not be less than 0.77Dt and the height not less than 0.8Dt.
3.1.4
The rudder stock is to be secured against axial sliding. The degree of the permissible axial clearance depends on theconstruction of the steering engine and on the bearing.
3.2
Strengthening of rudder stock
3.2.1
If the rudder is so arranged that additional bending stresses occur in the rudder stock, the stock diameter has to besuitably increased. The increased diameter is, where applicable, decisive for the scantlings of the coupling.
For the increased rudder stock diameter the equivalent stress of bending and torsion, in N/mm2, is not to exceed thefollowing value:118
s v = s b2 + 3t 2 £krwhere:
s b : Bending stress, in N/mm2, equal to:sb =10.2 M b
D13

Mb : Bending moment at the neck bearing, in N-mt : Torsional stress, in N/mm2, equal to:
5 .1 Q Rt=
D13
D1 : Increased rudder stock diameter, in cm, equal to:
D1 = 0.1Dt 6 1 +

4 æ Mb öç
3 çè QR ø

2

QR : As defined in 2.1.2, 2.2.2 and 2.2.3
Dt : As defined in 3.1.1.
Note:
Where a double-piston steering gear is fitted, additional bending moments may be transmitted fromthe steering gear into the rudder stock. These additional bending moments are to be taken into account for
determining the rudder stock diameter.
3.3
Analysis
3.3.1 General
The bending moments, shear forces and support forces for the system rudder - rudder stock are to be obtained from
3.3.2 and 3.3.3, for rudder types as shown in Fig. 3 to Fig. 7.
3.3.2 Data for the analysis
l 10 ,.., l 50 : Lengths, in m, of the individual girders of the system－357－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

I 10 ,.., I 50 : Moments of inertia of these girders, in cm4
For rudders supported by a sole piece the length l 20 is the distance between lower edge of rudder body and centreof sole piece, and I 20 is the moment of inertia of the pintle in the sole piece.
Load on rudder body, in kN/m, (general):CRpR =l 10 10 3
Load on semi-spade rudders, in kN/m:
C R2
p R10 =
l 10 10 3
C R1
p R 20 =l 20 10 3
CR, CR1, CR2 : As defined in 2.1 and 2.2
Z : Spring constant, in kN/m, of support in the sole piece or rudder horn respectively:
for the support in the sole piece (see Fig. 3):
6.18 I 50
Z=
l 350
for the support in the rudder horn (see Fig. 4):
1
Z=
fb + ftfb: Unit displacement of rudder horn, in m/kN, due to a unit force of 1 kN acting in the centre of support
1.3 d 3 10 8
fb=
3E In
f b = 0.21

In
ft

d3
In

(guidance value for steel): Moment of inertia of rudder horn, in cm4, around the x-axis at d/2 (see Fig. 4): Unit displacement due to a torsional moment of the amount 1, in m/kN
d e2
ft =
G Jt
ft =

d e 2 å ui / ti

3.14 108 FT2

for steel: Modulus of rigity, kN/m2:
G = 7.92 10 7 for steel
Jt : Torsional moment of inertia, in m4
FT : Mean sectional area of rudder horn, in m2
ui : Breadth, in mm, of the individual plates forming the mean horn sectional area
ti : Plate thickness of individual plate having breadth ui, in mme, d : Distances, in m, according to Fig. 4
K11, K22, K12 : Rudder horn compliance constants calculated for rudder horn with 2-conjugate elastic
supports (Fig.5).The 2-conjugate elastic supports are defined in terms of horizontal
displacements, yi, by the following equations:at the lower rudder horn bearing:y1 = - K12 B2 - K22 B1
at the upper rudder horn bearing:y2 = - K11 B2 - K12 B1
wherey1, y2 : Horizontal displacements, in m, at the lower and upper rudder horn bearings, respectively
B1, B2 : Horizontal support forces, in kN, at the lower and upper rudder horn bearings, respectively
K11, K22, K12 : Obtained, in m/kN, from the following formulae:
e2 l
l3
K 11 = 1.3+
3EJ 1h GJ th
G

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

é l3
l2 (d - l ) ù e 2 l
K12 = 1.3ê+ú+
2 EJ1h û GJ thë 3EJ1h
é l3
l2 (d - l ) l(d - l )2 (d - l )3 ù e 2 d
K 22 = 1.3ê
+
+
+
ú+
EJ1h
EJ1h
3EJ 2 h ûú GJ th
ëê 3EJ1hd: Height of the rudder horn, in m, defined in Fig. 5. This value is measured downwards from the upper
rudder horn end, at the point of curvature transition, till the mid-line of the lower rudder horn pintle
l : Length, in m, as defined in Fig. 5. This length is measured downwards from the upper rudder horn end,
at the point of curvature transition, till the mid-line of the upper rudder horn bearing. For l = 0, the above
formulae converge to those of spring constant Z for a rudder horn with 1-elastic support, and assuming ahollow cross section for this parte : Rudder-horn torsion lever, in m, as defined in Fig. 5 (value taken at z = d/2)
J1h : Moment of inertia of rudder horn about the x axis, in m4, for the region above the upper rudder hornbearing. Note that J1h is an average value over the length l (see Fig. 5)
J2h : Moment of inertia of rudder horn about the x axis, in m4, for the region between the upper and lower
rudder horn bearings. Note that J2h is an average value over the length d - l (see Fig. 5)
Jth : Torsional stiffness factor of the rudder horn, in m4
For any thin wall closed section
4 FT2
J th =uåi t ii
FT : Mean of areas enclosed by outer and inner boundaries of the thin walled section of rudder horn, in m2
ui : Length, in mm, of the individual plates forming the mean horn sectional area
ti : Thickness, in mm, of the individual plates mentioned above.
Note that the Jth value is taken as an average value, valid over the rudder horn height.
3.3.3 Moments and forces to be evaluateda) The bending moment MR and the shear force Q1 in the rudder body, the bending moment Mb in the neck bearing
and the support forces B1, B2, B3 are to be evaluated.
The so evaluated moments and forces are to be used for the stress analyses required by 3.2, 5, 9.1 and 9.2.
b) For spade rudders (see Fig. 6) the moments, in N-m, and forces, in N, may be determined by the following
formulae:æl (2 x + x 2 ) ö
M b = C R çç l 20 + 10 1
3( x1 + x 2 ) ø
è
Mb
l 30
B 2 = C R + B3

B3 =

c)

For spade rudders with rudders trunks supporting rudder force (see Fig. 7) the moments, in N-m, and forces, in N,
may be determined by the following formulae:
MR is the greatest of the following values:
MR = CR2 (l10 CG2Z)
MR = CR1 (CG1Z l10)
where :: Rudder force over the rudder blade area A1
CR1
CR2: Rudder force over the rudder blade area A2
CG1Z : Vertical position of the centre of gravity of the rudder blade area A1
CG2Z : Vertical position of the centre of gravity of the rudder blade area A2
MB = CR2 (l10 CG2Z)
B3 = (MB + MCR1) / (l20 + l30)
B2 = CR + B3－359－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Fig. 3Rudder supported by sole piece

40

I30

30

I10

Mb

B2

pR

20 I20

I40

10

B3

MR

I50

Z
B1

50

Semi-spade rudder (with 1-elastic support)

40

I40

B2

Mb

B1
pR20

d
2

d

I20

B3

30

I 30

Q1

Z

e
10

I10

Q

M

20

Fig. 4

SystempR10
SystemFig. 5

MQ

Semi-spade rudder (with 2-conjugate elastic supports)－360－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Fig. 6

Spade rudder

30

B3

20

B2

x2

10

Mb

x1

pR

SystemFig. 7

M

Q

Spade rudders with rudder trunks

3.4
Rudder trunk supporting rudder stock
3.4.1
Where the rudder stock is arranged in a trunk in such a way that the trunk is stressed by forces due to rudder action,
the scantlings of the trunk are to be as such that the equivalent stress due to bending and shear does not exceed
0.35 ReH of the material used.
3.4.2
In case where the rudder stock is fitted with a rudder trunk which is arranged in such a way the rudder trunk is loadedby the pressure induced on the rudder blade, as given in 2.1.1, the bending stress in the rudder trunk, in N/mm2, is to be
in compliance with the following formula:s £ 80 / k
where the material factor k for the rudder trunk is not to be taken less than 0.7.
For the calculation of the bending stress, the span to be considered is the distance between the mid-height of thelower rudder stock bearing and the point where the trunk is clamped into the shell or the bottom of the skeg.
3.4.3
The steel used for the rudder trunk is to be of weldable quality, with a carbon content not exceeding 0.23% on ladle
analysis and a carbon equivalent CEQ not exceeding 0.41.
3.4.4
The weld at the connection between the rudder trunk and the shell or the bottom of the skeg is to be full penetration.
The fillet shoulder radius r, in mm, is to be as large as practicable and to comply with the following formulae:－361－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

r = 60when s ³ 40 / k N/mm2
r = 0.1D1, without being less than 30,
when s < 40 / k N/mm2
where D1 is defined in 3.2.1.
The radius may be obtained by grinding. If disk grinding is carried out, score marks are to be avoided in the directionof the weld.
The radius is to be checked with a template for accuracy. Four profiles at least are to be checked. A report is to besubmitted to the Surveyor.
3.4.5
Before welding is started, a detailed welding procedure specification is to be submitted to the Society covering theweld preparation, welding positions, welding parameters, welding consumables, preheating, post weld heat treatment
and inspection procedures. This welding procedure is to be supported by approval tests in accordance with theapplicable requirements of materials and welding sections of this Part.
The manufacturer is to maintain records of welding, subsequent heat treatment and inspections traceable to the welds.
These records are to be submitted to the Surveyor.
3.4.6
Non destructive tests are to be conducted at least 24 hours after completion of the welding. The welds are to be 100%magnetic particle tested and 100% ultrasonic tested. The welds are to be free from cracks, lack of fusion and incomplete
penetration. The non destructive tests reports are to be handed over to the Surveyor.
3.4.7
Rudder trunks in materials other than steel are to be specially considered by the Society.
3.4.8
The thickness of the shell or of the bottom plate is to be compatible with the trunk thickness.
4.

Rudder couplings

4.1
General
4.1.1
The couplings are to be designed in such a way as to enable them to transmit the full torque of the rudder stock.
4.1.2
The distance of the bolt axis from the edges of the flange is not to be less than 1.2 times the diameter of the bolt. In
horizontal couplings, at least 2 bolts are to be arranged forward of the stock axis.
4.1.3
The coupling bolts are to be fitted bolts. The bolts and nuts are to be effectively secured against loosening.
4.1.4
For spade rudders, horizontal couplings according to 4.2 are permitted only where the required thickness of thecoupling flanges tf is less than 50 mm, otherwise cone coupling according to 4.4 or 4.5, as applicable, is to be applied.
For spade rudders of the high lift type, only cone coupling according to 4.4 or 4.5, as applicable, is permitted.
4.2
Horizontal couplings
4.2.1
The diameter of coupling bolts, in mm, is not to be less than:d b = 0.62

D 3kb
kr n ewhere:
D : Rudder stock diameter according to 6, in mm
n : Total number of bolts, which is not to be less than 6
e : Mean distance of the bolt axes from the centre of bolt system, in mm
kr : Material factor for the rudder stock as defined in 1.4.2
kb : Material factor for the bolts, obtained according to 1.4.2.
4.2.2
The thickness of the coupling flanges, in mm, is not to be less than determined by the following formulae:－362－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

t f = 0.62

D 3k fkr n e, without being less than 0.9d b

where:
kf : Material factor for the coupling flanges, obtained according to 1.4.2
The thickness of the coupling flanges clear of the bolt holes is not to be less than 0.65 t f .
The width of material outside the bolt holes is not to be less than 0.67d b .
4.2.3
The coupling flanges are to be equipped with a fitted key according to DIN 6885 or equivalent standard for relieving
the bolts.
The fitted key may be dispensed with if the diameter of the bolts is increased by 10%.
4.2.4
Horizontal coupling flanges are to be either forged together with the rudder stock or welded to the rudder stock,according to 10.1.3.
4.2.5
For the connection of the coupling flanges with the rudder body, see also 10.
4.3
Vertical couplings
4.3.1
The diameter of the coupling bolts, in mm, is not to be less than:
db =

0.81D
n

kb
kr

where:
D, kb, kr, n are defined in 4.2.1, where n is not to be less than 8.
4.3.2
The first moment of area of the bolts, in cm3, about the centre of the coupling is not to be less than:S = 0.00043D 3
4.3.3
The thickness of the coupling flanges, in mm, is not to be less than t f = d b
The width of material outside the bolt holes is not to be less than 0.67d b .
4.4
Cone couplings with key
4.4.1
Cone couplings should have a taper c on diameter of 1 : 8 to 1 : 12, where c = (d 0 - d u ) / l (see Fig. 8).
The cone shapes are to fit very exact. The nut is to be carefully secured, e.g. by a securing plate as shown in Fig. 8.
4.4.2
The coupling length l is to be, in general, not less than 1.5d 0 .
4.4.3
For couplings between stock and rudder a key is to be provided, the shear area of which, in cm2, is not to be less than:
17.55Q F
as =d k R eH 1
where:
QF : Design yield moment of rudder stock, in N-m according to 6
: Diameter of the conical part of the rudder stock, in mm, at the key
dk
ReH1 : Minimum yield stress of the key material, in N/mm2－363－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Fig. 8Cone coupling with key
d0
insulation
liner
sealing/
insulation

da
dm

hn

du

dg
dn

securing
plate for
nut

4.4.4
The effective surface area, in cm2, of the key (without rounded edges) between key and rudder stock or cone coupling
is not to be less than:
5Q F
ak =
d k R eH 2
where:
ReH2 : Minimum yield stress of the key, stock or coupling material, in N/mm2, whichever is less.
4.4.5
The dimensions of the slugging nut are to be as follows (see Fig. 8):・ height:
hn = 0.6dg
・ outer diameter, the greater value of:dn = 1.2 du or dn = 1.5 dg
・ external thread diameter:
dg = 0.65 d0
4.4.6
It is to be proved that 50% of the design yield moment will be solely transmitted by friction in the cone couplings.
This can be done by calculating the required push-up pressure and push-up length according to 4.5.3 for a torsional
moment Q' F = 0.5Q F .
4.5
Cone couplings with special arrangements for mounting and dismounting the couplings
4.5.1
Where the stock diameter exceeds 200 mm, the press fit is recommended to be effected by a hydraulic pressureconnection. In such cases the cone is to be more slender, c » 1 : 12 to » 1 : 20 .
4.5.2
In case of hydraulic pressure connections the nut is to be effectively secured against the rudder stock or the pintle. A
securing plate for securing the nut against the rudder body is not to be provided (see Fig. 9).

－364－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Fig. 9Securing
flat bar

Cone coupling without key

dg
d1

Note: A securing flat bar will be regarded as an effective securing device of the nut, if its shear area, in mm2, is notless than:
As =

Ps 3
ReH

where:
Ps : Shear force, in N, as follows:PS =öPe æç d1
m1
- 0. 6
ç dg
2
øèPe : Push-up force according to 4.5.3, in N
m1 : Frictional coefficient between nut and rudder body, normally m1 = 0.3
d1 : Mean diameter of the frictional area between nut and rudder bodydg : Thread diameter of the nut
ReH : Minimum yield stress, in N/mm2, of the securing flat bar material.
4.5.3 Push-up pressure and push-up length
For the safe transmission of the torsional moment by the coupling between rudder stock and rudder body the push-up
length and the push-up pressure are to be determined according to 4.5.4 and 4.5.5.
4.5.4 Push-up pressure
The push-up pressure is not to be less than the greater of the two following values:
2Q
p req1 = 2 F 10 3d m l p m0
p req 2 =

6 Mb
l2 dm

10 3

where:
QF : Design yield moment of rudder stock according to 6, in N-m
dm : Mean cone diameter, in mm
l : Cone length, in mm
m 0 : Frictional coefficient, equal to about 0.15
Mb : Bending moment in the cone coupling (e.g. in case of spade rudders), in N-m
It has to be proved that the push-up pressure does not exceed the permissible surface pressure in the cone. The
permissible surface pressure is to be determined by the following formula:
0.8 ReH 1 - a 2
p perm =
3+a 4

(

)

where:
ReH : Minimum yield stress, in N/mm2, of the material of the gudgeon－365－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

a=

dm
da

dm : Diameter, in mm, as defined in Fig. 8
da : Outer diameter of the gudgeon (see Fig. 8), in mm, to be not less than 1.5d m .
4.5.5 Push-up length
The push-up length, in mm, is not to be less than:p req d m
0.8Rtm
Dl 1 =+
2c
æ1- a ö
E çç
c
è 2 ø
where:
Rtm : Mean roughness, in mm, taken equal to about 0.01
c : Taper on diameter according to 4.5.1
The push-up length, in mm, is, however, not to be taken greater than:
1.6 ReH d m
0.8 Rtm+
Dl 2 =4c
E c 3+a
Note: In case of hydraulic pressure connections the required push-up force Pe for the cone, in N, may be
determined by the following formula:æcö
Pe = preq d mp lç + 0.02
è2
ø
The value 0.02 is a reference for the friction coefficient using oil pressure. It varies and depends on the mechanicaltreatment and roughness of the details to be fixed.
Where due to the fitting procedure a partial push-up effect caused by the rudder weight is given, this may be taken
into account when fixing the required push-up length, subject to approval by the Society.
4.5.6 Push-up pressure for pintle bearings
The required push-up pressure for pintle bearings, in N/mm2, is to be determined by the following formula:Bdp req = 0.4 12 0dm l
where:: Supporting force in the pintle bearing, in N (see Fig. 4)
B1dm, l : As defined in 4.5.3: Pintle diameter, in mm, according to Fig. 8.
d0
5.

Rudder body, rudder bearings

5.1
Strength of rudder body
5.1.1
The rudder body is to be stiffened by horizontal and vertical webs in such a manner that the rudder body will beeffective as a beam. The rudder should be additionally stiffened at the aft edge.
5.1.2
The strength of the rudder body is to be proved by direct calculation according to 3.3
5.1.3
For rudder bodies without cut-outs the permissible stress are limited to:・ bending stress, in N/mm2, due to MR defined in 3.3.3:
s b = 110・ shear stress, in N, due to Q1 defined in 3.3.3:
t t = 50・ equivalent stress due to bending and shear:s v = s b 2 + 3t 2 = 120－366－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

In case of openings in the rudder plating for access to cone coupling or pintle nut the permissible stresses according
to 5.1.4 apply. Smaller permissible stress values may be required if the corner radii are less than 0.15ho , where ho is
the height of opening.
5.1.4
In rudder bodies with cut-outs (semi-spade rudders) the following stress values are not to be exceeded:・ bending stress, N/mm2, due to MR:
s b = 75
・ shear stress, N/mm2, due to Q1:
t = 50・ torsional stress, N/mm2,due to Mt:
t t = 50・ equivalent stress, in N/mm2, due to bending and shear and equivalent stress due to bending and torsion:s v1 = s b2 + 3t 2 = 100
s v 2 = s b2 + 3t t2 = 100
where:
M R = C R 2 f 1 + B1

f2
, in N-m
2

Q1 = CR2, in N
f1, f2 : As defined in Fig. 10tt: Torsional stress, in N/mm2, taken equal to:
Mt
tt =
2lht
M t = C R 2 e , in N-m
CR2 : Partial rudder force, in N, of the partial rudder area A2 below the cross section under consideratione: Lever for torsional moment, in m (horizontal distance between the centre of pressure of area A2 and thecentre line a-a of the effective cross sectional area under consideration, see Fig. 10. The centre ofpressure is to be assumed at 0.33c 2 aft of the forward edge of area A2, where c 2 is the mean breadthof area A2).
h, l, t : Dimensions, in cm, as defined in Fig. 10.
The distance l between the vertical webs should not exceed 1.2h .
The radii in the rudder plating are not to be less than 4 to 5 times the plate thickness, but in no case less than 50 mm.
Note: It is recommended to keep the natural frequency of the fully immersed rudder and of local structuralcomponents at least 10 % above the exciting frequency of the propeller (number of revolutions numberof blades) or if relevant above higher order.
Fig. 10

Geometry of rudder
A-B
2

r

A2
a

t

B

x

h

A

f1

r

f2

a

2
a

a
e

－367－

x

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

5.2
Rudder plating
5.2.1
The thickness of the rudder plating, in mm, is to be determined according to the following formula:t P = 1.74a b p R k + 2.5

where:
CR, in kN/m2
103 A
a : Smaller unsupported width of a plate panel, in m.
pR = 10T +æaö
b = 1.1 - 0.5çèbø

2max, 1.0, if

b
³ 2.5
a

b : greatest unsupported width of a plate panel, in m.
However, the thickness is to be not less than the thickness of the shell plating at aft part according to Ch 9, Sec 2.
Regarding dimensions and welding, 10.1.1 is to be comply with.
5.2.2
For connecting the side plating of the rudder to the webs tenon welding is not to be used. Where application of fillet
welding is not practicable, the side plating is to be connected by means of slot welding to flat bars which are welded to
the webs.
5.2.3
The thickness of the webs, in mm, is not to be less than 70 % of the thickness of the rudder plating according to 5.2.1,
but not less than:t min = 8 k

Webs exposed to seawater are to be dimensioned according to 5.2.1.
5.3
Connections of rudder blade structure with solid parts in forged or cast steel
5.3.1 General
Solid parts in forged or cast steel which ensure the housing of the rudder stock or of the pintle are in general to beconnected to the rudder structure by means of two horizontal web plates and two vertical web plates.
5.3.2 Minimum section modulus of the connection with the rudder stock housing
The section modulus of the cross-section of the structure of the rudder blade which is connected with the solid part
where the rudder stock is housed, which is made by vertical web plates and rudder plating, is to be not less than thatobtained, in cm3, from the following formula:2

æ H -HX ö k
10 - 4w S = c S d 13 çç E
H
k
E
ø 1
è
where:: Coefficient, to be taken equal to:cS
cS = 1.0 if there is no opening in the rudder plating or if such openings are closed by a full penetration
welded platecS = 1.5 if there is an opening in the considered cross-section of the rudder
D1 : Rudder stock diameter, in mm, defined in 3.2.1
HE : Vertical distance, in m, between the lower edge of the rudder blade and the upper edge of the solid part
HX : Vertical distance, in m, between the considered cross-section and the upper edge of the solid partk, k1 : Material factors, defined for the rudder blade plating and the rudder stock, respectively.
5.3.3 Calculation of the actual section modulus of the connection with the rudder stock housing
The actual section modulus of the cross-section of the structure of the rudder blade which is connected with the solidpart where the rudder stock is housed is to be calculated with respect to the symmetrical axis of the rudder.
The breadth of the rudder plating to be considered for the calculation of this actual section modulus is to be notgreater than that obtained, in m, from the following formula:Hb = sV + 2 X
mwhere:－368－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

sV : Spacing, in m, between the two vertical webs (see Fig. 11)
HX : Distance defined in 5.3.2
m : Coefficient to be taken, in general, equal to 3.
Where openings for access to the rudder stock nut are not closed by a full penetration welded plate, they are to be
deducted (see Fig. 11).
5.3.4 Thickness of horizontal web plates
In the vicinity of the solid parts, the thickness of the horizontal web plates, as well as that of the rudder blade plating
between these webs, is to be not less than the greater of the values obtained, in mm, from the following formulae:tH = 1.2 tP
d2t H = 0.045 S
sH
where:
tP : Defined in 5.2.1
dS : Diameter, in mm, to be taken equal to:for the solid part connected to the rudder stockdS = D1
for the solid part connected to the pintle
dS = daD1 : Rudder stock diameter, in mm, defined in 3.2.1
da : Pintle diameter, in mm, defined in 5.5.1
sH : Spacing, in mm, between the two horizontal web plates.
Different thickness may be accepted when justified on the basis of direct calculations submitted to the Society for
approval.
Fig. 11

Cross-section of the connection between rudder blade structure
and rudder stock housing

5.3.5 Thickness of side plating and vertical web plates welded to the solid part
The thickness of the vertical web plates welded to the solid part where the rudder stock is housed as well as the
thickness of the rudder side plating under this solid part is to be not less than the values obtained, in mm, from Table 2.

－369－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Table 2Thickness of side plating and vertical web plates

Type of rudder

Thickness of vertical web plates,

Thickness of rudder plating,

in mm

in mm

Rudder blade

At opening

Rudder blade

Area withwithout opening

boundary

without opening

opening

Rudder supported by sole piece (Fig 3)

1.2tP

1.6 tP

1.2 tP

1.4 tP

Semi-spade and spade rudders (Fig 4 to Fig 7)

1.4 tP

2.0 tP

1.3 tP

1.6 tPtP : Defined in 5.2.1

5.3.6 Solid part protrusions
The solid parts are to be provided with protrusions. Vertical and horizontal web plates of the rudder are to be butt
welded to these protrusions.
These protrusions are not required when the web plate thickness is less than:・ 10 mm for web plates welded to the solid part on which the lower pintle of a semi-spade rudder is housed and forvertical web plates welded to the solid part of the rudder stock coupling of spade rudders
・ 20 mm for the other web plates.
5.3.7
If the torque is transmitted by a prolonged shaft extended into the rudder, the latter must have the diameter Dt or D1,
whichever is greater, at the upper 10 % of the intersection length. Downwards it may be tapered to 0.6Dt, in spaderudders to 0.4 times the strengthened diameter, if sufficient support is provided for.
5.4
Rudder bearings
5.4.1
In way of bearings liners and bushes are to be fitted.
Their minimum thickness is equal to:・ tmin = 8 mm for metallic materials and synthetic material
・ tmin = 22 mm for lignum material
Where in case of small ships bushes are not fitted, the rudder stock is to be suitably increased in diameter in way ofbearings enabling the stock to be re-machined later.
5.4.2
An adequate lubrication is to be provided.
5.4.3
The bearing forces result from the direct calculation mentioned in 3.3. As a first approximation the bearing force may
be determined without taking account of the elastic supports. This can be done as follows:・ normal rudder with two supports:
The rudder force CR is to be distributed to the supports according to their vertical distances from the centre ofgravity of the rudder area.
・ semi-spade rudders:
support force in the rudder horn, in N:b
B1 = C R
csupport force in the neck bearing, in N:
B 2 = C R - B1
For b and c see Fig. 14.
5.4.4
The projected bearing surface Ab ( bearing height
B
Ab =
q

external diameter of liner ), in mm2, is not to be less thanwhere:
B : Support force, in N
q : Permissible surface pressure according to Table 3.

－370－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

5.4.5
Stainless and wear resistant steels, bronze and hot-pressed bronze-graphit materials have a considerable difference inpotential to non-alloyed steel. Respective preventive measures are required.
5.4.6
The bearing height is to be equal to the bearing diameter, however, is not to exceed 1.2 times the bearing diameter.
Where the bearing depth is less than the bearing diameter, bearing material is to allow higher specific surfacepressures.
Table 3

Surface pressure q of bearing materials
q, in N/mm2

Bearing material
Lignum vitae

2.5White metal, oil lubricated

4.5

(1)

Synthetic material

5.5

Steel(2), bronze and hot-pressed bronze-graphite materials

7.0(1) Synthetic materials to be of approved type.
Surface pressures exceeding 5.5 N/mm2 may be accepted in accordance with bearing
manufacturer's specification and tests, but in no case more than 10 N/mm2.
(2) Stainless and wear resistant steel in an approved combination with stock liner. Higher surfacepressures than 7 N/mm2 may be accepted if verified by tests.

The wall thickness of pintle bearings in sole piece and rudder horn is to be approximately equal to one fourth of thepintle diameter.
5.5
Pintles
5.5.1
Pintles are to have scantlings complying with the conditions given in 4.4 and 4.6. The pintle diameter, in mm, is not
to be less than:d a = 0.35 B1 k r

where:
B1 : Support force, in N
kr : Material factor defined in 1.4.2.
5.5.2
The thickness of any liner or bush, in mm, is neither to be less than:t = 0.01 B1

nor than the minimum thickness defined in 5.4.1.
5.5.3
Where pintles are of conical shape, the taper on diameter is to comply with the following:
・ 1 : 8 to 1 : 12 , if keyed by slugging nut
・ 1 : 12 to 1 : 20 , if mounted with oil injection and hydraulic nut
5.5.4
The pintles are to be arranged in such a manner as to prevent unintentional loosening and falling out.
For nuts and threads the requirements of 4.4.5 and 4.5.2 apply accordingly.
5.6
Criteria for bearing clearances
5.6.1
For metallic bearing material the bearing clearance, in mm, is to be not less:db+ 1 .01000
where:
db : Inner diameter of bush, in mm.

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5.6.2
If non-metallic bearing material is applied, the bearing clearance is to be specially determined considering thematerial's swelling and thermal expansion properties.
5.6.3
The clearance is not to be taken less than 1.5 mm on diameter. In case of self lubricating bushes going down below
this value can be agreed to on the basis of the manufacturer's specification.
6.

Design yield moment of rudder stock

6.1
General
6.1.1
The design yield moment of the rudder stock is to be determined by the following formula:
D3
Q F = 0.02664 t
kr
Dt : Stock diameter, in mm, according to 3.1.
Where the actual diameter Dta is greater than the calculated diameter Dt, the diameter Dta is to be used. However, Dtaapplied to the above formula need not be taken greater than 1.145Dt .
7.

Stopper, locking device

7.1
Stopper
7.1.1
The motions of quadrants or tillers are to be limited on either side by stoppers. The stoppers and their foundations
connected to the ship's hull are to be of strong construction so that the yield point of the applied materials is notexceeded at the design yield moment of the rudder stock.
7.2
Locking device
7.2.1
Each steering gear is to be provided with a locking device in order to keep the rudder fixed at any position. This
device as well as the foundation in the ship's hull are to be of strong construction so that the yield point of the appliedmaterials is not exceeded at the design yield moment of the rudder stock as specified in 6. Where the ship's speed
exceeds 12 knots, the design yield moment need only be calculated for a stock diameter based on a speed V0 = 12 knots.
7.3
7.3.1
Regarding stopper and locking device see also the applicable requirements of 15.4.8, Part D.
8.

Propeller nozzles

8.1
General
8.1.1
The following requirements are applicable to propeller nozzles having an inner diameter of up to 5 m. Nozzles withlarger diameters will be specially considered.
8.1.2
Special attention is to be given to the support of fixed nozzles at the hull structure.
8.2
Design pressure
8.2.1
The design pressure for propeller nozzles, in kN/m2, is to be determined by the following formula:pd = c pd 0
N
pd 0 = eAp
where:
N : Maximum shaft power, in kW－372－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Ap : Propeller disc area, in m2, taken equal to:p
Ap = D 2
4
D : Propeller diameter, in m
e : Factor obtained from the following formula:Ne = 0.21 - 2 10 -4, without being taken less than 0.1
Ap
c : Coefficient taken equal to (see Fig. 12):c = 1.0
in zone 2 (propeller zone)c = 0.5
in zones 1 and 3
c = 0.35
in zone 4.
Fig. 12

Zones of propeller nozzlebzone 4zone 3min. b/4

zone 2zone 1

8.3
Plate thickness
8.3.1
The thickness of the nozzle shell plating, in mm, is not to be less than:t = t 0 + t k , without being taken less than 7.5
where:
t0 : Thickness, in mm, obtained from the following formula:t 0 = 5a p d

a : Spacing of ring stiffeners, in m
tk : Corrosion allowance, in mm, taken equal to:t k = 1.5
if t 0 £ 10
é æ t
ù
ö
t k = min ê0.1 çç 0 + 0.5 , 3.0úøëê è kûú

if t 0 > 10

8.3.2
The web thickness of the internal stiffening rings is not to be less than the nozzle plating for zone 3, however, in nocase be less than 7.5 mm.
8.4
Section modulus
8.4.1
The section modulus of the cross section shown in Fig. 12 around its neutral axis, in cm3, is not to be less than:w = n d 2 b V02
where:
d : Inner diameter of nozzle, in mb : Length of nozzle, in m
n : Coefficient taken equal to:n = 1.0 , for rudder nozzles
n = 0.7 , for fixed nozzles.

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8.5
Welding
8.5.1
The inner and outer nozzle shell plating is to be welded to the internal stiffening rings as far as practicable by double
continuous welds. Plug welding is only permissible for the outer nozzle plating.
9.

Rudder horn and sole piece scantlings

9.1
Sole piece
9.1.1
The section modulus of the sole piece related to the z-axis, in cm3, is not to be less than:B xk
Wz = 180
where:
B1 : As defined in 3.3. For rudders with two supports the support force is approximately B1 = CR/2, when theelasticity of the sole piece is ignored.
x : Distance, in m, of the respective cross section from the rudder axis, with:xmin = 0.5 l 50
xmax = l 50
l 50 : As defined in Fig. 13 and 3.3.2.
Fig. 13

Sole pieceA

Section A - A
z
y

y
z

A
x
50

9.1.2
The section modulus related to the y-axis is not to be less than:・ where no rudder post or rudder axle is fittedW
Wy = z2・ where a rudder post or rudder axle is fittedW
Wy = z3
9.1.3
The sectional area, in mm2, at the location x = l 50 is not to be less than:
As =

B1
k
48

9.1.4
The equivalent stress taking into account bending and shear stresses, in N/mm2, at any location within the length l 50
is not to exceed:s v = s b2 + 3t 2 =115
kwhere:－374－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

sb =
t=

B1 x
Wz

B1
As

9.2
Rudder horn of semi spade rudders (case of 1-elastic support)
9.2.1
The distribution of the bending moment, in N-m, shear force, in N, and torsional moment, in N-m, is to be determinedaccording to the following formulae:
M b = B1 z
・ bending moment:
M b max = B1 d・ shear force:

Q = B1・ torsional moment:

M T = B1 e( z )For determining preliminary scantlings the flexibility of the rudder horn may be ignored and the supporting force B1,
in N, be calculated according to the following formula:b
B1 = CRcwhere b, c, d, e(z) and z are defined in Fig. 14 and Fig. 15.
b results from the position of the centre of gravity of the rudder area.
Fig. 14

Dimensions of rudder horn

Rudder horn loads
B1 · dB1 · e(z)B1dFig. 15

z

z
e(z)

Mb

Q

MT

9.2.2
The section modulus of the rudder horn in transverse direction related to the horizontal x-axis is at any location z, incm3, not to be less than:－375－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 1)

Wx =

Mb k
67

9.2.3
At no cross section of the rudder horn the shear stress, in N/mm2, due to the shear force Q is to exceed the value:
48t=k
The shear stress, in N/mm2, is to be determined by the following formula:
B
t= 1
Ah
where:Ah : Effective shear area of the rudder horn, in mm2, in y-direction
9.2.4
The equivalent stress, in N/mm2, at any location z of the rudder horn is not to exceed the following value:120s v = s b2 + 3 t 2 + t T2 =kwhere:
M
sb = b
Wx
MT
tT =
10 3
2 AT t h()

AT : Sectional area, in mm2, enclosed by the rudder horn at the location consideredt h : Thickness of the rudder horn plating, in mm.
9.2.5
When determining the thickness of the rudder horn plating the provisions of 5.2 to 5.4 are to be complied with. The
thickness, in mm, is, however, not to be less than 2.4 LCSR - B K .
9.2.6
The rudder horn plating is to be effectively connected to the aft ship structure, e.g. by connecting the plating tolongitudinal girders, in order to achieve a proper transmission of forces, see Fig. 16.
Fig. 16

Connection of rudder horn to aft ship structure

9.2.7
Transverse webs of the rudder horn are to be led into the hull up to the next deck in a sufficient number and must beof adequate thickness.

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9.2.8
Strengthened plate floors are to be fitted in line with the transverse webs in order to achieve a sufficient connection
with the hull. The thickness of these plate floors is to be increased by 50% above the bottom thickness determinedaccording to Ch 6, Sec 1 or Ch 9, Sec 2.
9.2.9
The centre line bulkhead (wash-bulkhead) in the after peak is to be connected to the rudder horn.
9.2.10
Where the transition between rudder horn and shell is curved, about 50% of the required total section modulus of therudder horn is to be formed by the webs in a section A - A located in the centre of the transition zone, i.e. 0.7r above thebeginning of the transition zone (See Fig. 17).
Transition between rudder horn and shell

r

A

0,7r

Fig. 17A

9.3
Rudder horn of semi spade rudders (case of 2-conjugate elastic supports)
9.3.1 Bending moment
The bending moment acting on the generic section of the rudder horn is to be obtained, in N-m, from the following
formulae:・ between the lower and upper supports provided by the rudder horn:
MH = FA1 z
・ above the rudder horn upper-support:
MH = FA1 z + FA2 (z - dlu)
where:
FA1 : Support force at the rudder horn lower-support, in N, to be obtained according to Fig. 5, and taken equal
to B1
FA2 : Support force at the rudder horn upper-support, in N, to be obtained according to Fig. 5, and taken equal
to B2
z : Distance, in m, defined in Fig. 19, to be taken less than the distance d, in m, defined in the same figure
dlu : Distance, in m, between the rudder-horn lower and upper bearings (according to Fig. 18, dlu = d - l ).

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Fig. 18

Geometrical parameters for the calculation of the bending moment in rudder horn

9.3.2 Shear force
The shear force QH acting on the generic section of the rudder horn is to be obtained, in N, from the following
formulae:・ between the lower and upper rudder horn bearings:
QH = FA1・ above the rudder horn upper-bearing:
QH = FA1 + FA2
where:
FA1, FA2 : Support forces, in N.
9.3.3 Torque
The torque acting on the generic section of the rudder horn is to be obtained, in N-m, from the following formulae:
・ between the lower and upper rudder horn bearings:
MT = FA1 e(z)・ above the rudder horn upper-bearing:
MT = FA1 e(z) + FA2 e(z)where:
FA1, FA2 : Support forces, in N
: Torsion lever, in m, defined in Fig. 19.
e(z)

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Fig. 19

Geometry of rudder horn

9.3.4 Shear stress calculationa) For a generic section of the rudder horn, located between its lower and upper bearings, the following stresses are to
be calculated:tS : Shear stress, in N/mm2, to be obtained from the following formula:Ft S = A1
AH

tT : Torsional stress, in N/mm2, to be obtained for hollow rudder horn from the following formula:
tT =

b)

M T 103
2 FT tH

For solid rudder horn, tT is to be considered by the Society on a case by case basis
For a generic section of the rudder horn, located in the region above its upper bearing, the following stresses are to
be calculated:tS : Shear stress, in N/mm2, to be obtained from the following formula:
F + FA2t S = A1
AH

tT : Torsional stress, in N/mm2, to be obtained for hollow rudder horn from the following formula:tT =M T 103
2 FT tH

For solid rudder horn, tT is to be considered by the Society on a case by case basis
where:
FA1, FA2 : Support forces, in N
AH : Effective shear sectional area of the rudder horn, in mm2, in y-direction
MT : Torque, in N-m
FT : Mean of areas enclosed by outer and inner boundaries of the thin walled section of rudder horn, in m2
tH: Plate thickness of rudder horn, in mm. For a given cross section of the rudder horn, the maximum valueof tT is obtained at the minimum value of tH.
9.3.5 Bending stress calculation
For the generic section of the rudder horn within the length d, defined in Fig. 14, the following stresses are to be
calculated:sB : Bending stress, in N/mm2, to be obtained from the following formula:M
sB = HWX
MH : Bending moment at the section considered, in N-m
WX : Section modulus, in cm3, around the X-axis (see Fig. 19).

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9.3.6 General remarks
Requirements 9.2.5 to 9.2.10 also apply to rudder horn with 2-conjugate elastic supports.
10.

Rudder coupling flanges

10.1.1
Unless forged or cast steel flanges with integrally forged or cast welding flanges are used, horizontal rudder coupling
flanges are to be joined to the rudder body by plates of graduated thickness and full penetration single or double-bevel
welds as prescribed in Ch 11, Sec 1 (see Fig. 20).
Fig. 20

Horizontal rudder coupling flangesttf= thickness of rudder plating, in mm= actual flange thickness, in mm
tf+ 5 , in mm, where tf < 50 mmt¢ =3t ¢ = 3 t f , in mm, where tf

50 mm

10.1.2
Allowance is to be made for the reduced strength of the coupling flange in the thickness direction. In case of doubt,
proof by calculation of the adequacy of the welded connection shall be produced.
10.1.3
The welded joint between the rudder stock (with thickened collar, see Ch11, Sec 2) and the flange is to be made inaccordance with Fig. 21.

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Fig. 21

Welded joint between rudder stock and coupling flange

a 1 1
= to
b 3 5

11.

Azimuth propulsion system

11.1
General11.1.1 Arrangement
The azimuth propulsion system is constituted by the following sub-systems (see Fig. 22):・ the steering unit
・ the bearing
・ the hull supports
・ the rudder part of the system・ the pod, which contains the electric motor in the case of a podded propulsion system.
Fig. 22

Azimuth propulsion system

11.1.2 Application
The requirements of this Article apply to the scantlings of the hull supports, the rudder part and the pod.
The steering unit and the bearing are to comply with the relevant requirements of Part D.

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11.1.3 Operating conditions
The maximum angle at which the azimuth propulsion system can be oriented on each side when the ship navigates at
its maximum speed is to be specified by the Designer. Such maximum angle is generally to be less than 35 on eachside.
In general, orientations greater than this maximum angle may be considered by the Society for azimuth propulsion
systems during manoeuvres, provided that the orientation values together with the relevant speed values are submitted
to the Society for approval.
11.2
Arrangement
11.2.1 Plans to be submitted
In addition to the plans showing the structural arrangement of the pod and the rudder part of the system, the plans
showing the arrangement of the azimuth propulsion system supports are to be submitted to the Society for approval.
The scantlings of the supports and the maximum loads which act on the supports are to be specified in these drawings.
11.2.2 Locking device
The azimuth propulsion system is to be mechanically lockable in a fixed position, in order to avoid rotations of thesystem and propulsion in undesirable directions in the event of damage.
11.3
Design loads
11.3.1The lateral pressure to be considered for scantling of plating and ordinary stiffeners of the azimuth propulsion system
is to be determined for an orientation of the system equal to the maximum angle at which the azimuth propulsion
system can be oriented on each side when the ship navigates at its maximum speed.
・ The total force which acts on the azimuth propulsion system is to be obtained by integrating the lateral pressure on
the external surface of the system.
・ The calculations of lateral pressure and total force are to be submitted to the Society for information.
11.4
Plating
11.4.1 Plating of the rudder part of the azimuth propulsion system
The thickness of plating of the rudder part of the azimuth propulsion system is to be not less than that obtained, in mm,from the formulae in 5.2.1, in which the term CR /A is to be replaced by the lateral pressure calculated according to 11.3.
11.4.2 Plating of the pod
The thickness of plating of the pod is to be not less than that obtained, in mm, from the formulae in Ch 6, Sec 1 or Ch
9, Sec 2, where the lateral pressure is to be calculated according to 11.3.
11.4.3 Webs
The thickness of webs of the rudder part of the azimuth propulsion system is to be determined according to 5.2.3,
where the lateral pressure is to be calculated according to 11.3.
11.5
Ordinary stiffeners
11.5.1 Ordinary stiffeners of the pod
The scantlings of ordinary stiffeners of the pod are to be not less than those obtained from the formulae in Ch 6, Sec
2 or Ch 9, Sec 2, where the lateral pressure is to be calculated according to 11.3.
11.6
Primary supporting members
11.6.1 Analysis criteria
The scantlings of primary supporting members of the azimuth propulsion system are to be obtained by the Designer
through direct calculations, to be carried out according to the following requirements:
・ the structural model is to include the pod, the rudder part of the azimuth propulsion system, the bearing and thehull supports
・ the boundary conditions are to represent the connections of the azimuth propulsion system to the hull structures
・ the loads to be applied are those defined in 11.6.2.
・ The direct calculation analyses (structural model, load and stress calculation, strength checks) carried out by the
Designer are to be submitted to the Society for information.

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11.6.2 Loads
The following loads are to be considered by the Designer in the direct calculation of the primary supporting membersof the azimuth propulsion system:
・ gravity loads
・ buoyancy
・ maximum loads calculated for an orientation of the system equal to the maximum angle at which the azimuth
propulsion system can be oriented on each side when the ship navigates at its maximum speed
・ maximum loads calculated for the possible orientations of the system greater than the maximum angle at therelevant speed (see 11.1.3)
・ maximum loads calculated for the crash stop of the ship obtained through inversion of the propeller rotation
・ maximum loads calculated for the crash stop of the ship obtained through a 180 rotation of the pod.
11.6.3 Strength check
It is to be checked that the Von Mises equivalent stress sE in primary supporting members, calculated, in N/mm2, forthe load cases defined in 11.6.2, is in compliance with the following formula:s E £ s ALL
where:
sALL : Allowable stress, in N/mm2, to be taken equal to the lesser of the following values:s ALL = 0.275R m
s ALL = 0.55ReH
11.7
Hull supports of the azimuth propulsion system
11.7.1 Analysis criteria
The scantlings of hull supports of the azimuth propulsion system are to be obtained by the Designer through direct
calculations, to be carried out in accordance with the requirements in 11.6.1.
11.7.2 Loads
The loads to be considered in the direct calculation of the hull supports of the azimuth propulsion system are thosespecified in 11.6.2.
11.7.3 Strength check
It is to be checked that the Von Mises equivalent stress sE in hull supports, in N/mm2, calculated for the load cases
defined in 11.6.2, is in compliance with the following formula:s E £ s ALL
where:
sALL : Allowable stress, in N/mm2, equal to 65 / kr
kr
: Material factor, defined in 1.4.2
Values of sE greater than sALL may be accepted by the Society on a case by case basis, depending on the localisationof sE and on the type of direct calculation analysis.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 2)

Section 2
1.

BULWARKS AND GUARD RAILS

General1.1
Introduction
1.1.1
The requirements of this Section apply to the arrangement of bulwarks and guard rails provided at boundaries of thefreeboard deck, superstructure decks and tops of the first tier of deckhouses located on the freeboard deck.
1.2
General
1.2.1
Efficient bulwarks or guard rails are to be fitted at the boundaries of all exposed parts of the freeboard deck andsuperstructure decks directly attached to the freeboard deck, as well as the first tier of deckhouses fitted on the
freeboard deck and the superstructure ends.
1.2.2
The height of the bulwarks or guard rails is to be at least 1 m from the deck. However, where their height wouldinterfere with the normal operation of the ship, a lesser height may be accepted, if adequate protection is provided andsubject to any applicable statutory requirement.
1.2.3
Where superstructures are connected by trunks, open rails are to be fitted for the whole length of the exposed parts ofthe freeboard deck.
1.2.4
In type B-100 ships, open rails on the weather parts of the freeboard deck for at least half the length of the exposedparts are to be fitted.
Alternatively, freeing ports complying with Ch 9, Sec 6, 5.5.2 are to be fitted.
1.2.5
In ships with bulwarks and trunks of breadth not less than 0.6B, which are included in the calculation of freeboard,
open rails on the weather parts of the freeboard deck in way of the trunk for at least half the length of the exposed parts
are to be fitted.
Alternatively, freeing ports complying with Ch 9, Sec 6, 5.3.1 are to be fitted.
1.2.6
In ships having superstructures which are open at either or both ends, adequate provision for freeing the space withinsuch superstructures is to be provided.
1.2.7
The freeing port area in the lower part of the bulwarks is to be in compliance with the applicable requirements of Ch
9, Sec 6, 5.
2.

Bulwarks

2.1
General2.1.1
As a rule, plate bulwarks are to be stiffened at the upper edge by a suitable bar and supported either by stays or platebrackets spaced not more than 2.0 m apart.
The free edge of the stay or the plate bracket is to be stiffened.
Stays and brackets of bulwarks are to be aligned with the beams located below or are to be connected to them bymeans of local transverse stiffeners.
As an alternative, the lower end of the stay and bracket may be supported by a longitudinal stiffener.
2.1.2
In type B-60 and B-100 ships, the spacing forward of 0.07LCSR-B from the fore end of brackets and stays is to be notgreater than 1.2 m.

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2.1.3
Where bulwarks are cut completely, the scantlings of stays or brackets at ends are to be increased with respect tothose given in 2.2.
2.1.4
As a rule, bulwarks are not to be connected either to the upper edge of the sheerstrake plate or to the stringer plate.
Failing this, the detail of the connection will be examined by the Society.
2.1.5
Constructions of bulwarks are to comply with the requirements in 23.1.3-4 to -6, Part C in addition to therequirements in this section.
2.2
Scantlings
2.2.1
The gross thickness of bulwarks on the freeboard deck not exceeding 1 m in height is to be not less than 6.5 mm.
Where the height of the bulwark is equal to or greater than 1.8 m, its thickness is to be equal to that calculated for theside of a superstructure situated in the same location as the bulwark.
For bulwarks between 1 m and 1.8 m in height, their thickness is to be calculated by linear interpolation.
2.2.2
Bulwark plating and stays are to be adequately strengthened in way of eye plates used for shrouds or other tackles in
use for cargo gear operation, as well as in way of hawser holes or fairleads provided for mooring or towing.
2.2.3
At the ends of partial superstructures and for the distance over which their side plating is tapered into the bulwark, thelatter is to have the same thickness as the side plating. Where openings are cut in the bulwark at these positions,adequate compensation is to be provided either by increasing the thickness of the plating or by other suitable means.
2.2.4
The gross section modulus of stays in way of the lower part of the bulwark is to be not less than the value obtained, in
cm3, from the following formula:w = 77 shB2
where:
s : Spacing of stays, in m
hB : Height of bulwark, in m, measured from the top of the deck plating to the upper edge.
The actual section of the connection between stays and deck structures is to be taken into account when calculating
the above section modulus.
To this end, the bulb or face plate of the stay may be taken into account only where welded to the deck; in this casethe beam located below is to be connected by double continuous welding.
For stays with strengthening members not connected to the deck, the calculation of the required section modulus isconsidered by the Society on a case by case basis.
At the ends of the ship, where the bulwark is connected to the sheerstrake, an attached plating having a width notexceeding 600 mm may also be included in the calculation of the actual gross section modulus of stays.
2.2.5
Openings in bulwarks are to be arranged so that the protection of the crew is to be at least equivalent to that provided
by the horizontal courses in 3.1.2.
For this purpose, vertical rails or bars spaced approximately 230 mm apart may be accepted in lieu of rails or bars
arranged horizontally.
2.2.6
In the case of ships intended for the carriage of timber deck cargoes, the specific provisions of the freeboard
regulations are to be complied with.
3.

Guard rails

3.1
General
3.1.1
Where guard rails are provided, the upper edge of sheerstrake is to be kept as low as possible.

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3.1.2
The opening below the lowest course is to be not more than 230 mm. The other courses are to be not more than 380
mm apart.
3.1.3
In the case of ships with rounded gunwales or sheerstrake, the stanchions are to be placed on the flat part of the deck.
3.1.4
Fixed, removable or hinged stanchions are to be fitted about 1.5 m apart. At least every third stanchion is to besupported by a bracket or stay.
Removable or hinged stanchions are to be capable of being locked in the upright position.
3.1.5
Wire ropes may only be accepted in lieu of guard rails in special circumstances and then only in limited lengths.
Wires are to be made taut by means of turnbuckles.
3.1.6
Chains may only be accepted in short lengths in lieu of guard rails if they are fitted between two fixed stanchions
and/or bulwarks.

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Section 3

EQUIPMENT

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
EN : Equipment number defined in 2.1

1.

General

1.1
General1.1.1
The requirements in this Section apply to temporary mooring of a ship within or near harbour, or in a sheltered area,
when the ship is awaiting a berth, the tide, etc.
Therefore, the equipment complying with the requirements in this Section is not intended for holding a ship off fully
exposed coasts in rough weather or for stopping a ship which is moving or drifting.
1.1.2
The equipment complying with the requirements in this Section is intended for holding a ship in good holding
ground, where the conditions are such as to avoid dragging of the anchor. In poor holding ground the holding power of
the anchors is to be significantly reduced.
1.1.3
The equipment number EN formula for anchoring equipment required here under is based on an assumed current
speed of 2.5 m/s, wind speed of 25 m/s and a scope of chain cable between 6 and 10, the scope being the ratio between
length of chain paid out and water depth.
1.1.4
It is assumed that under normal circumstances a ship will use one anchor only.
2.

Equipment number

2.1
Equipment number
2.1.1 General
All ships are to be provided with equipment in anchors and chain cables, to be obtained from Table 1, based on theirequipment number EN.
In general, stockless anchors are to be adopted.
For ships with EN greater than 16000, the determination of the equipment will be considered by the Society on a caseby case basis.
Table 1Equipment number EN

Equipment

Stockless anchors

A < EN £ B

Mass perN (1)anchor,Stud link chain cables for anchors
Diameter, in mm

Total length,
in m

Grade 1

Grade 2

180

220.0

14.0

12.5

2

240

220.0

16.0

14.0

2

300

247.5

17.5

16.0

130

2

360

247.5

19.0

17.5

130

150

2

420

275.0

20.5

17.5

150

175

2

480

275.0

22.0

19.0

175

205

2

570

302.5

24.0

20.5

A

B

50

70

2

70

90

90

110

110

in kg

－387－

Grade 3

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

Equipment number EN

Stockless anchors

A < EN £ B

Mass perN (1)anchor,Stud link chain cables for anchors
Diameter, in mm

Total length,
in m

Grade 1

Grade 2

Grade 3

660

302.5

26.0

22.0

20.5

780

330.0

28.0

24.0

22.0

3

900

357.5

30.0

26.0

24.0

3

1020

357.5

32.0

28.0

24.0

400

3

1140

385.0

34.0

30.0

26.0

400

450

3

1290

385.0

36.0

32.0

28.0

450

500

3

1440

412.5

38.0

34.0

30.0

500

550

3

1590

412.5

40.0

34.0

30.0

550

600

3

1740

440.0

42.0

36.0

32.0

600

660

3

1920

440.0

44.0

38.0

34.0

660

720

3

2100

440.0

46.0

40.0

36.0

720

780

3

2280

467.5

48.0

42.0

36.0

780

840

3

2460

467.5

50.0

44.0

38.0

840

910

3

2640

467.5

52.0

46.0

40.0

910

980

3

2850

495.0

54.0

48.0

42.0

980

1060

3

3060

495.0

56.0

50.0

44.0

1060

1140

3

3300

495.0

58.0

50.0

46.0

1140

1220

3

3540

522.5

60.0

52.0

46.0

1220

1300

3

3780

522.5

62.0

54.0

48.0

1300

1390

3

4050

522.5

64.0

56.0

50.0

1390

1480

3

4320

550.0

66.0

58.0

50.0

1480

1570

3

4590

550.0

68.0

60.0

52.0

1570

1670

3

4890

550.0

70.0

62.0

54.0

1670

1790

3

5250

577.5

73.0

64.0

56.0

1790

1930

3

5610

577.5

76.0

66.0

58.0

1930

2080

3

6000

577.5

78.0

68.0

60.0

2080

2230

3

6450

605.0

81.0

70.0

62.0

2230

2380

3

6900

605.0

84.0

73.0

64.0

2380

2530

3

7350

605.0

87.0

76.0

66.0

2530

2700

3

7800

632.5

90.0

78.0

68.0

2700

2870

3

8300

632.5

92.0

81.0

70.0

2870

3040

3

8700

632.5

95.0

84.0

73.0

3040

3210

3

9300

660.0

97.0

84.0

76.0

3210

3400

3

9900

660.0

100.0

87.0

78.0

3400

3600

3

10500

660.0

102.0

90.0

78.0

3600

3800

3

11100

687.5

105.0

92.0

81.0

3800

4000

3

11700

687.5

107.0

95.0

84.0

4000

4200

3

12300

687.5

111.0

97.0

87.0

4200

4400

3

12900

715.0

114.0

100.0

87.0

4400

4600

3

13500

715.0

117.0

102.0

90.0

4600

4800

3

14100

715.0

120.0

105.0

92.0

4800

5000

3

14700

742.5

122.0

107.0

95.0

5000

5200

3

15400

742.5

124.0

111.0

97.0

5200

5500

3

16100

742.5

127.0

111.0

97.0

5500

5800

3

16900

742.5

130.0

114.0

100.0

5800

6100

3

17800

742.5

132.0

117.0

102.0

A

B

205

240

3

240

280

3

280

320

320

360

360

in kg

－388－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

Equipment number EN

Stockless anchors

A < EN £ B

Mass perN (1)anchor,

A

B

6100

6500

3

18800

6500

6900

3

20000

6900

7400

3

7400

7900

3

7900

8400

8400
8900

Stud link chain cables for anchors
Diameter, in mm

Total length,
in m

Grade 2

Grade 3

742.5

120.0

107.0

770.0

124.0

111.0

21500

770.0

127.0

114.0

23000

770.0

132.0

117.0

3

24500

770.0

137.0

122.0

8900

3

26000

770.0

142.0

127.0

9400

3

27500

770.0

147.0

132.0

9400

10000

3

29000

770.0

152.0

132.0

10000

10700

3

31000

770.0

137.0

10700

11500

3

33000

770.0

142.0

11500

12400

3

35500

770.0

147.0

12400

13400

3

38500

770.0

152.0

13400

14600

3

42000

770.0

157.0

14600

16000

3

46000

770.0

162.0

in kg

Grade 1

(1) See 3.2.4.

2.1.2 Equipment number
The equipment number EN is to be obtained from the following formula:
EN = D 2/3 + 2 h B + 0.1 A
where:.
D : Moulded displacement of the ship, in t, to the summer load waterline
h : Effective height, in m, from the summer load waterline to the top of the uppermost house, to be obtainedin accordance with the following formula:h = a + hn
When calculating h, sheer and trim are to be disregarded
a : Freeboard amidships from the summer load waterline to the upper deck, in m
hn : Height, in m, at the centreline of tier n of superstructures or deckhouses having a breadth greater thanB/4. Where a house having a breadth greater than B/4 is above a house with a breadth of B/4 or less, theupper house is to be included and the lower ignored
A : Area, in m2, in profile view, of the parts of the hull, superstructures and houses above the summer loadwaterline which are within the length LCSR-B and also have a breadth greater than B/4
Fixed screens or bulwarks 1.5 m or more in height are to be regarded as parts of houses when determining h and A. In
particular, the hatched area shown in Fig. 1 is to be included.
The height of hatch coamings and that of any deck cargo, such as containers, may be disregarded when determining
h and A.
Fig. 1

Effective area of bulwarks or fixed screen to be included in the equipment number－389－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

3.

Equipment

3.1
General
3.1.1
All anchoring equipment, towing bitts, mooring bollards, fairlead cleats and eyebolts are to be so constructed andattached to the hull that, in use up to design loads, the integrity of the ship will not be impaired.
3.1.2
The anchoring arrangement is to be such as to prevent the cable from being damaged and fouled. Adequate
arrangement is to be provided to secure the anchor under all operational conditions.
3.2
Anchors
3.2.1 General
The scantlings of anchors are to be in compliance with the following requirements.
Anchors are to be constructed and tested in compliance with approved plans.
3.2.2 Ordinary anchors
The required mass for each anchor is to be obtained from Table 1.
The individual mass of a main anchor may differ by 7% from the mass required for each anchor, provided that the
total mass of anchors is not less than the total mass required in Table 1.
The mass of the head of an ordinary stockless anchor, including pins and accessories, is to be not less than 60% of thetotal mass of the anchor.
Where a stock anchor is provided, the mass of the anchor, excluding the stock, is to be not less than 80% of the massrequired in Table 1 for a stockless anchor. The mass of the stock is to be not less than 25% of the mass of the anchor
without the stock but including the connecting shackle.
3.2.3 High and very high holding power anchors
High holding power (HHP) and very high holding power (VHHP) anchors, i.e. anchors for which a holding power
higher than that of ordinary anchors has been proved according to the applicable requirements of Chapter 2, Part L,
do not require testing regarding to 3.2.5 or 3.2.6, respectively.
Where HHP or VHHP anchors are used as bower anchors, the mass of each anchor is to be not less than 75% or 50%,
respectively, of that required for ordinary stockless anchors in Table 1.
The mass of VHHP anchors is to be, in general, less than or equal to 1500 kg.
3.2.4 Third anchor
Where three anchors are provided, two are to be connected to their own chain cables and positioned on board always
ready for use.
The third anchor is intended as a spare and is not required for the purpose of classification.
3.2.5 Test for high holding power anchors approval
For approval and/or acceptance as a HHP anchor, comparative tests are to be performed on various types of sea
bottom.
Such tests are to show that the holding power of the HHP anchor is at least twice the holding power of an ordinary
stockless anchor of the same mass.
For approval and/or acceptance as a HHP anchor of a whole range of mass, such tests are to be carried out on anchors
whose sizes are, as far as possible, representative of the full range of masses proposed. In this case, at least two anchorsof different sizes are to be tested. The mass of the maximum size to be approved is to be not greater than 10 times the
maximum size tested. The mass of the smallest is to be not less than 0.1 times the minimum size tested.
3.2.6 Test for very high holding power anchors approval
For approval and/or acceptance as a VHHP anchor, comparative tests are to be performed at least on three types ofsea bottom: soft mud or silt, sand or gravel and hard clay or similar compounded material. Such tests are to show thatthe holding power of the VHHP anchor is to be at least four times the holding power of an ordinary stockless anchor of
the same mass or at least twice the holding power of a previously approved HHP anchor of the same mass. The holding
power test load may be less than or equal to the proof load of the anchor, where deemed as appropriate by the Society.
For approval and/or acceptance as a VHHP anchor of a whole range of mass, such tests are to be carried out onanchors whose sizes are, as far as possible, representative of the full range of masses proposed. In this case, at least
three anchors of different sizes are to be tested, relevant to the bottom, middle and top of the mass range.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

3.2.7 Specification for test on high holding power and very high holding power anchors
Tests are generally to be carried out from a tug. Shore based tests may be accepted by the Society on a case by casebasis.
Alternatively, sea trials by comparison with a previous approved anchor of the same type (HHP or VHHP) of the one
to be tested may be accepted by the Society on a case by case basis.
For each series of sizes, the two anchors selected for testing (ordinary stockless and HHP anchors for testing HHP
anchors, ordinary stockless and VHHP anchors or, when ordinary stockless anchors are not available, HHP and VHHP
anchors for testing VHHP anchors) are to have the same mass.
The length of chain cable connected to each anchor, having a diameter appropriate to its mass, is to be such that thepull on the shank remains practically horizontal. For this purpose a value of the ratio between the length of the chain
cable paid out and the water depth equal to 10 is considered normal. A lower value of this ratio may be accepted by theSociety on a case by case basis.
Three tests are to be carried out for each anchor and type of sea bottom.
The pull is to be measured by dynamometer; measurements based on the RPM/bollard pull curve of tug may,
however, be accepted instead of dynamometer readings.
Note is to be taken where possible of the stability of the anchor and its ease of breaking out.
3.3
Chain cables for anchors
3.3.1 Material
The chain cables are classified as grade 1, 2 or 3 depending on the type of steel used and its manufacture.
The characteristics of the steel used and the method of manufacture of chain cables are to be approved by the Society
for each manufacturer. The material from which chain cables are manufactured and the completed chain cables
themselves are to be tested in accordance with the applicable requirements of Part K and Chapter 3, Part L.
Chain cables made of grade 1 may not be used with high holding power and very high holding power anchors.
3.3.2 Scantlings of stud link chain cables
The mass and geometry of stud link chain cables, including the links, are to be in compliance with the requirementsin the applicable requirements of Chapter 3, Part L.
The diameter of stud link chain cables is to be not less than the value in Table 1.
3.3.3 Studless link chain cables
For ships with EN less than 90, studless short link chain cables may be accepted by the Society as an alternative tostud link chain cables, provided that the equivalence in strength is based on proof load, defined in the applicablerequirements of Chapter 3, Part L and that the steel grade of the studless chain is equivalent to the steel grade of thestud chains it replaces, as defined in 3.3.1.
3.3.4 Chain cable arrangement
Chain cables are to be made by lengths of 27.5 m each, joined together by Dee or lugless shackles.
The total length of chain cable, required in Table 1, is to be divided in approximately equal parts between the two
anchors ready for use.
Where different arrangements are provided, they are considered by the Society on a case by case basis.
Where the ship may anchor in areas with current speed greater than 2.5 m/s, the Society may require a length ofheavier chain cable to be fitted between the anchor and the rest of the chain in order to enhance anchor bedding.
Attachment pieces
3.4
3.4.1 General
Where the lengths of chain cable are joined to each other by means of shackles of the ordinary Dee type, the anchor
may be attached directly to the end link of the first length of chain cable by a Dee type end shackle.
A detachable open link in two parts riveted together may be used in lieu of the ordinary Dee type end shackle; in suchcase the open end link with increased diameter, defined in 3.4.2, is to be omitted.
Where the various lengths of chain cable are joined by means of lugless shackles and therefore no special end andincreased diameter links are provided, the anchor may be attached to the first length of chain cable by a special
pear-shaped lugless end shackle or by fitting an attachment piece.
3.4.2 Scantlings
The diameters of the attachment pieces, in mm, are to be not less than the values indicated in Table 2.

－391－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

Attachment pieces may incorporate the following items between the increased diameter stud link and the open end
link:
・ swivel, having a diameter equal to 1.2d・ increased stud link, having a diameter equal to 1.1d
Where different compositions are provided, they will be considered by the Society on a case by case basis.
Table 2

Diameters of attachment pieces

Attachment piece

Diameter, in mm

End shackle

1.4dOpen end link

1.2d

Increased stud link

1.1dCommon stud linkdLugless shackledwhere:
d : Diameter, in mm, of the common link.

3.4.3 Material
Attachment pieces, joining shackles and end shackles are to be of such material and design as to provide strength
equivalent to that of the attached chain cable, and are to be tested in accordance with the applicable requirements of theapplicable requirements of Chapter 3, Part L.
3.4.4 Spare attachment pieces
A spare pear-shaped lugless end shackle or a spare attachment piece is to be provided for use when the spare anchor
is fitted in place.
3.5
Towlines and mooring lines
3.5.1 General
The towlines having the characteristics defined in Table 3 are intended as those belonging to the ship to be towed bya tug or another ship.
3.5.2 Materials
Towlines and mooring lines may be of wire, natural or synthetic fibre or a mixture of wire and fibre.
The breaking loads defined in Table 3 refer to steel wires or natural fibre ropes.
Steel wires and fibre ropes are to be tested in accordance with the applicable requirements in the applicablerequirements of Chapter 4 and Chapter 5, Part L.
3.5.3 Steel wires
Steel wires are to be made of flexible galvanised steel and are to be of types defined in Table 4.
Where the wire is wound on the winch drum, steel wires to be used with mooring winches may be constructed withan independent metal core instead of a fibre core. In general such wires are to have not less than 186 threads in addition
to the metallic core.

－392－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

Table 3Equipment number EN
A < EN

Towlines and mooring lines

Towline (1)B

Mooring lines

Minimum

Breaking load,

length, in m

in kN

Length of each line,

Breaking load,

in m

in kN

70

180

98.1

3

80

34

70

90

180

90

110

180

98.1

3

100

37

98.1

3

110

39

110

130

180

98.1

3

110

44

130
150

150

180

98.1

3

120

49

175

180

98.1

3

120

54

175

205

180

112

3

120

59

205

240

180

129

4

120

64

240

280

180

150

4

120

69

280

320

180

174

4

140

74

320

360

180

207

4

140

78

360

400

180

224

4

140

88

400

450

180

250

4

140

98

450

500

180

277

4

140

108

500

550

190

306

4

160

123

550

600

190

338

4

160

132

600

660

190

371

4

160

147

660

720

190

406

4

160

157

720

780

190

441

4

170

172

780

840

190

480

4

170

186

840

910

190

518

4

170

201

910

980

190

550

4

170

216

980

1060

200

603

4

180

230

1060

1140

200

647

4

180

250

1140

1220

200

692

4

180

270

1220

1300

200

739

4

180

284

1300

1390

200

786

4

180

309

1390

1480

200

836

4

180

324

1480

1570

220

889

5

190

324

1570

1670

220

942

5

190

333

1670

1790

220

1024

5

190

353

1790

1930

220

1109

5

190

378

1930

2080

220

1168

5

190

402

2080

2230

240

1259

5

200

422

2230

2380

240

1356

5

200

451

2380

2530

240

1453

5

200

481

2530

2700

260

1471

6

200

481

2700

2870

260

1471

6

200

490

2870

3040

260

1471

6

200

500

3040

3210

280

1471

6

200

520

3210

3400

280

1471

6

200

554

3400

3600

280

1471

6

200

588

3600

3800

300

1471

6

200

612

3800

4000

300

1471

6

200

647

A

B

50

－393－

N (2)

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

Equipment number EN
A < EN

Towline (1)B

Mooring lines

Minimum

Breaking load,

Length of each line,

Breaking load,

length, in m

in kN

300

1471

7

in m

in kN

200

647

4400

300

1471

7

200

657

4400

4600

300

4600

4800

300

1471

7

200

667

1471

7

200

677

4800

5000

300

1471

7

200

686

5000

5200

300

1471

8

200

686

5200

5500

300

1471

8

200

696

5500

5800

300

1471

8

200

706

5800

6100

300

1471

9

200

706

6100

6500

9

200

716

6500

6900

9

200

726

6900

7400

10

200

726

7400

7900

11

200

726

7900

8400

11

200

735

8400

8900

12

200

735

A

B

4000

4200

4200

N (2)

8900

9400

13

200

735

9400

10000

14

200

735

10000

10700

15

200

735

10700

11500

16

200

735

11500

12400

17

200

735

12400

13400

18

200

735

13400

14600

19

200

735

14600

16000

21

200

735

(1)

The towline is not compulsory. It is recommended for ships having length not greater than 180 m.

(2)

See 3.5.4.

Table 4

Steel wire composition
Steel wire components

Breaking load BL, in kN
Number of threads

Ultimate tensile strength of
threads, in N/mm2

Composition of wireBL< 216

72

1420

1570

6 strands with 7-fibre core216 < BL< 490

144

1570

1770

6 strands with 7-fibre core

BL > 490

216 or 222

1770

1960

6 strands with 1-fibre core

3.5.4 Number of mooring lines
When the breaking load of each mooring line is greater than 490 kN, either a greater number of mooring lines thanthose required in Table 3 having lower strength, or a lower number of mooring lines than those required in Table 3
having greater strength may be used, provided the total breaking load of all lines aboard the ship is greater than thevalue defined in Table 3.
In any case, the number of lines is to be not less than 6 and the breaking load of each line is to be greater than 490 kN.
3.5.5 Length of mooring lines
The length of individual mooring lines may be reduced by up to 7% of the length defined in Table 3, provided thatthe total length of mooring lines is greater than that obtained by adding the lengths of the individual lines defined inTable 3.

－394－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

3.5.6 Equivalence between the breaking loads of synthetic and natural fibre ropes
Generally, fibre ropes are to be made of polyamide or other equivalent synthetic fibres.
The equivalence between the breaking loads of synthetic fibre ropes BLS and of natural fibre ropes BLN is to beobtained, in kN, from the following formula:
8/9
B LS = 7.4 d (B LN )where:: Elongation to breaking of the synthetic fibre rope, to be assumed not less than 30%.
3.6
Hawse pipes
3.6.1
Hawse pipes are to be built according to sound marine practice.
Their position and slope are to be so arranged as to create an easy lead for the chain cables and efficient housing forthe anchors, where the latter are of the retractable type, avoiding damage to the hull during these operations.
For this purpose chafing lips of suitable form with ample lay-up and radius adequate to the size of the chain cable are
to be provided at the shell and deck. The shell plating in way of the hawse pipes is to be reinforced as necessary.
3.6.2
In order to obtain an easy lead of the chain cables, the hawse pipes may be provided with rollers. These rollers are tohave a nominal diameter not less than 10 times the size of the chain cable where they are provided with full imprints,
and not less than 12 times its size where provided with partial imprints only.
3.6.3
All mooring units and accessories, such as timbler, riding and trip stoppers are to be securely fastened to theSurveyor s satisfaction.
3.7
Windlass
3.7.1 General
The windlass, which is generally single, is to be power driven and suitable for the size of chain cable and the mass of
the anchors.
The windlass is to be fitted in a suitable position in order to ensure an easy lead of the chain cables to and through thehawse pipes. The deck in way of the windlass is to be suitably reinforced.
3.7.2 Assumptions for the calculation of the continuous duty pull
The calculation of the continuous duty pull PC that the windlass unit prime mover is to be able to supply is based on
the following assumptions:・ ordinary stockless anchors
・ wind force equal to 6 on Beaufort Scale・ water current velocity 3 knots
・ anchorage depth 100 m
・ PC includes the influences of buoyancy and hawse pipe efficiency; the latter is assumed equal to 70%
・ the anchor masses assumed are those defined in the applicable requirements of Chapter 2, Part L, excluding
tolerances
・ only one anchor is assumed to be raised at a time.
Owing to the buoyancy, the chain masses assumed are smaller than those defined in the applicable requirements ofChapter 3, Part L, and are obtained, per unit length of the chain cable, in kg/m, from the following formula:mL = 0.0218 d2
where d is the chain cable diameter, in mm.
3.7.3 Calculation of the continuous duty pull
According to the assumptions in 3.7.2, the windlass unit prime mover is to be able to supply for a least 30 minutes acontinuous duty pull PC to be obtained, in kN, from Table 5.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

Table 5

Continuous duty pullMaterial of chain cables

Continuous duty pull,in kN

Mild steel

PC = 0.0375 d2

High tensile strength steel

PC = 0.0425 d2

Very high tensile strength steel

PC = 0.0475 d2

where:
d : Chain cable diameter, in mm.

3.7.4 Temporary overload capacity
The windlass unit prime mover is to provide the necessary temporary overload capacity for breaking out the anchor.
The temporary overload capacity, or short term pull, is to be not less than 1.5 times the continuous duty pull PC and it
is to be provided for at least two minutes.
The speed in this overload period may be lower than the nominal speed specified in 3.7.5.
3.7.5 Nominal hoisting speed
The nominal speed of the chain cable when hoisting the anchor and cable, to be assumed as an average speed, is to be
not less than 0.15 m/s.
The speed is to be measured over two shots of chain cable during the entire trip; the trial is to commence with 3 shots(82.5 m) of chain fully submerged.
3.7.6 Windlass brake
A windlass brake is to be provided having sufficient capacity to stop the anchor and chain cable when paying out thelatter with safety, in the event of failure of the power supply to the prime mover. Windlasses not actuated by steam arealso to be provided with a non-return device.
A windlass with brakes applied and the cable lifter declutched is to be able to withstand a pull of 45% of the breaking
load of the chain without any permanent deformation of the stressed parts or brake slip.
3.7.7 Chain stoppers
Where a chain stopper is fitted, it is to be able to withstand a pull of 80% of the breaking load of the chain.
Where a chain stopper is not fitted, the windlass is to be able to withstand a pull of 80% of the breaking load of thechain without any permanent deformation of the stressed part or brake slip.
3.7.8 Green sea loads
Where the height of the exposed deck in way of the item is less than 0.1LCSR-B or 22 m above the summer loadwaterline, whichever is the lesser, the securing devices of windlasses located within the forward quarter length of theship are to resist green sea forces.
The green sea pressure and associated areas are to be taken equal to (see Fig. 2):・ 200 kN/m2 normal to the shaft axis and away from the forward perpendicular, over the projected area in thisdirection
・ 150 kN/m2 parallel to the shaft axis and acting both inboard and outboard separately, over the multiple of f times
the projected area in this direction,
where:
f : Coefficient taken equal toB
f = 1+, but not greater than 2.5
H
B : Width of windlass measured parallel to the shaft axis,
H : Overall height of windlass.
Where mooring winches are integral with the anchor windlass, they are to be considered as part of the windlass.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

Fig. 2

Direction of forces and weight

Note:
Py to be examined from both inboard and outboard directions separately see 3.7.8. The sign convention for yi isreversed when Py is from the opposite direction as shown.

3.7.9 Forces in the securing devices of windlasses due to green sea loads
Forces in the bolts, chocks and stoppers securing the windlass to the deck are to be calculated by considering thegreen sea loads specified in 3.7.8.
The windlass is supported by N bolt groups, each containing one or more bolts (see also Fig. 3).
The axial force Ri in bolt group (or bolt) i, positive in tension, is to be obtained, in kN, from the following formulae:
・ Rxi = Px h xi Ai / Ix
・ Ryi = Py h yi Ai / Iy
・ Ri = Rxi + Ryi Rsi
where:
Px : Force, in kN, acting normal to the shaft axis
Py : Force, in kN, acting parallel to the shaft axis, either inboard or outboard, whichever gives the greater
force in bolt group ih: Shaft height, in cm, above the windlass mounting
xi, yi : X and Y co-ordinates, in cm, of bolt group i from the centroid of all N bolt groups, positive in the
direction opposite to that of the applied force: Cross-sectional area, in cm2, of all bolts in group i
Ai
Ix, Iy : Inertias, for N bolt groups, equal to:Ix = Ai xi2
Iy = Ai yi2
Rsi : Static reaction force, in kN, at bolt group i, due to weight of windlass.
Shear forces Fxi, Fyi applied to the bolt group i, and the resultant combined force Fi are to be obtained, in kN, from thefollowing formulae:
・ Fxi = (Px - g M) / N
・ Fyi = (Py - g M) / N
・ Fi = (Fxi2 + Fyi2 )0.5

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

where:: Coefficient of friction, to be taken equal to 0.5
M : Mass, in t, of windlass
N: Number of bolt groups.
Axial tensile and compressive forces and lateral forces calculated according to these requirements are also to beconsidered in the design of the supporting structure.
Fig. 3Sign convention

3.7.10 Strength criteria for windlass subject to anchor and chain loads
The stresses on the parts of the windlass, its frame and stopper are to be less than the yield stress of the material used.
For the calculation of the above stresses, special attention is to be paid to:・ stress concentrations in keyways and other stress raisers
・ dynamic effects due to sudden starting or stopping of the prime mover or anchor chain
・ calculation methods and approximation.
3.7.11 Strength criteria for securing devices of windlass
Tensile axial stresses in the individual bolts in each bolt group i are to be calculated according to the requirements
specified in 3.7.9. The horizontal forces Fxi and Fyi, to be calculated according to the requirements specified in 3.7.9, arenormally to be reacted by shear chocks.
Where "fitted" bolts are designed to support these shear forces in one or both directions, the equivalent Von Mises
stress , in N/mm2, in the individual bolt is to comply with following formula:£ 0.5 BPL
where BPL is the stress in the bolt considered as being loaded by the proof load.
Where pourable resins are incorporated in the holding down arrangements, due account is to be taken in thecalculations.
3.7.12 Connection with deck
The windlass, its frame and the stoppers are to be efficiently bedded to the deck.
3.8
Chain stoppers
3.8.1
A chain stopper is generally to be fitted between the windlass and the hawse pipe in order to relieve the windlass ofthe pull of the chain cable when the ship is at anchor. A chain stopper is to be capable of withstanding a pull of 80% of
the breaking load of the chain cable. The deck at the chain stopper is to be suitably reinforced.
For the same purpose, a piece of chain cable may be used with a rigging screw capable of supporting the weight of
the anchor when housed in the hawse pipe or a chain tensioner. Such arrangements are not to be considered as chain
stoppers.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 10 Section 3)

3.8.2
Where the windlass is at a distance from the hawse pipes and no chain stoppers are fitted, suitable arrangements areto be provided to lead the chain cables to the windlass.
3.9
Chain locker
3.9.1
The capacity of the chain locker is to be adequate to stow all chain cable equipment and provide an easy direct lead to
the windlass.
3.9.2
Where two chains are used, the chain lockers are to be divided into two compartments, each capable of housing thefull length of one line.
3.9.3
The inboard ends of chain cables are to be secured to suitably reinforced attachments in the structure by means of end
shackles, whether or not associated with attachment pieces.
Generally, such attachments are to be able to withstand a force not less than 15% of the breaking load of the chain
cable.
In an emergency, the attachments are to be easily released from outside the chain locker.
3.9.4
Where the chain locker is arranged aft of the collision bulkhead, its boundary bulkheads are to be watertight and adrainage system is to be provided.
3.10
Fairleads and bollards
3.10.1
Fairleads and bollards of suitable size and design are to be fitted for towing, mooring and warping operations.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 1)

Chapter 11

CONSTRUCTION AND TESTING

Section 1
1.

CONSTRUCTION

Structural details

1.1
Cut-outs, plate edges
1.1.1
The free edges (cut surfaces) of cut-outs, hatch corners, etc. are to be properly prepared and are to be free fromnotches. As a general rule, cutting draglines, etc. are not to be welded out, but are to be smoothly ground. All edges
are to be broken or in cases of highly stressed parts, be rounded off.
Free edges on flame or machine cut plates or flanges are not to be sharp cornered and are to be finished off as laid
down in above. This also applies to cutting drag lines, etc., in particular to the upper edge of shear strake andanalogously to weld joints, changes in sectional areas or similar discontinuities.
1.1.2
The hatch opening corners are to be machine cut.
1.2
Cold forming
1.2.1
For cold forming (bending, flanging, beading) of corrugated bulkhead the inside bending radius is to be not lessthan 2t (t = as-built thickness).
In order to prevent cracking, flame cutting flash or sheering burrs are to be removed before cold forming. After
cold forming all structural components and, in particular, the ends of bends (plate edges) are to be examined forcracks. Except in cases where edge cracks are negligible, all cracked components are to be rejected. Repair welding is
not permissible.
1.3
Assembly, alignment
1.3.1
The use of excessive force is to be avoided during the assembly of individual structural components or during theerection of sections. As far as possible, major distortions of individual structural components are to be corrected
before further assembly.
Structural members are to be aligned following the IACS recommendation No.47 provisions given in Table 1 oraccording to the requirements of a recognised fabrication standard that has been accepted by the Classification
Society. In the case of critical components, control drillings are to be made where necessary, which are then to bewelded up again on completion.
After completion of welding, straightening and aligning are to be carried out in such a manner that the material
properties are not influenced significantly. In case of doubt, the Society may require a procedure test or a working
test to be carried out.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 1)

Table 1
DetailAlignment (t, t1 and t2 : as-built thickness)
Standard

Limit

Remarks

Alignment of butt welds

a0.15t strength membera0.2t otherbut maximum 4.0 mm

t is the lesser plate
thickness

Alignment of fillet welds
Alternatively, heel line
Strength member andcan be used to check thehigher stress member:a t1/3
Other:alignment.

a

t1/2

Where t3 is less than t1,
then t3 should besubstituted for t1.

Alignment of fillet welds

Strength member andhigher stress member:at1/3

Other:at1/2

Alternatively, heel line
can be used to check thealignment.
Where t3 is less than t1,
then t3 should besubstitute for t1.

Note:strength means the following elements: strength deck, inner bottom, bottom, lower stool, lower part of transverse
bulkhead, bilge hopper and side frames of single side bulk carriers.

－401－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 1)

Table 1

Alignment (t, t1 and t2 : as-built thickness) (continued)

DetailStandard

Limit

Remarks

Alignment of face plates of T
longitudinalStrength memberaa = 8.0 mm

0.04b

Alignment of height of T-bar,
L-angle bar or bulb
Strength membera0.15 ta = 3.0 mm

Other
a

0.2 t

d

L / 50Alignment of panel stiffenerNote:strength means the following elements: strength deck, inner bottom, bottom, lower stool, lower part of transverse
bulkhead, bilge hopper and side frames of single side bulk carriers.

－402－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

Section 2
1.

WELDING

General1.1
Application
1.1.1
The requirements of this Section apply to the preparation, execution and inspection of welded connections in hull
structures.
1.1.2
Welding of hull parts is to be carried out by approved welders only.
1.1.3
Welding procedures and welding consumables approved for the types of connection and parent material inquestion are to be used.
1.1.4
Welding of connections is to be executed according to the approved plans.
1.1.5
The quality standard adopted by the shipyard is to be submitted to the Society and it applies to all welded
connections unless otherwise specified on a case by case basis.
1.1.6
Completed weld joints are to be to the satisfaction of the attending Surveyor.
1.1.7
Non destructive examination (NDE) for weld is to be carried out at the position indicated by the test plan in orderto ensure that the welds are free from cracks and internal harmful imperfections and defects.
1.2
Welding consumables and procedures
1.2.1
Welding consumables adopted are to be approved by the Society. The requirements for the approval of welding
consumables are given in the provisions of Part M.
1.2.2
The welding procedures adopted are to be approved by the Society. The requirements for the approval of welding
procedures are given in the provisions of Part M.
1.2.3
Suitable welding consumables are to be selected depending on the kind and grade of materials. The requirementsof the selection of welding consumables are given in the provision of Part M.
1.3
Welders and NDE operators
1.3.1 Welders
Manual and semi-automatic welding is to be performed by welders certified by the Society as specified in theprovisions of Part M.
1.3.2 Automatic welding operators
Personnel manning automatic welding machines and equipment are to be competent and sufficiently trained
deemed as appropriate by the Society.
1.3.3 NDE operator
NDE is to be carried out by qualified personnel certified by the Society or by recognized bodies in compliance withappropriate standards.
1.4
Documentation to be submitted
1.4.1
The welding application plan to be submitted for approval has to contain the necessary data relevant to thefabrication by welding of the structures, kinds of welding procedure applied, welding position, etc.

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2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

1.4.2
The NDE plan to be submitted for approval has to contain the necessary data relevant to the locations and numberof examinations, welding procedure(s) applied, method of NDE applied, etc.
2.

Types of welded connections

2.1
General
2.1.1
The type of welded connections and the edge preparation are to be appropriate to the welding procedure adopted.
2.2
Butt welding
2.2.1 General
Butt connections of plating are to be full penetration, welded on both sides except where special welding
procedures approved by the Society is applied.
2.2.2 Welding of plates with different thicknesses
In the case of welding of plates with a difference in as-built thickness greater than 4 mm, the thicker plate isnormally to be tapered. The taper has to have a length of not less than 3 times the difference in as-built thickness.
2.2.3 Edge preparation, root gap
Edge preparations and root gaps are to be in accordance with the adopted welding procedure and relevant bevel
preparation.
2.3
Tee or cross joints
2.3.1 General
The connections of primary supporting members and stiffener webs to plating as well as plating abutting on
another plating, are to be made by fillet welding or deep penetration weld, as shown in Fig. 1.
Fig. 1

Tee or cross joints

t : As-built thickness of abutting plate, in mm
f : Unwelded root face, in mm, taken as f £ t / 3
tl : Leg length of the fillet weld, in mm
tt : Throat thickness, in mm.
2.4
Full penetration welds
2.4.1 Application
Full penetration welds are to be used in the following connections:・ rudder horns and shaft brackets to shell structure
・ rudder side plating to rudder stock connection areas
・ vertical corrugated bulkhead to inner bottom plating that are situated in the cargo area and arranged withouttransverse lower stool・ vertical corrugated bulkhead to top plating of transverse lower stool
・ pillars to plating member, in case the stress acting on the pillar is tension (i.e. engine room, fore peak anddeckhouses).
・ edge reinforcement or pipe penetrations both to strength deck, sheer strake and bottom plating within 0.6LCSR-B
amidships, when the dimension of the opening exceeds 300 mm－404－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

・ abutting plate panels with as-built thickness less than or equal to 12 mm, forming boundaries to the sea below
the summer load waterline. For as-built thickness greater than 12 mm, deep penetration weld with a maximum
root face length f = T/3 is acceptable (see Fig. 2).
2.4.2
In case where shedder plates are fitted at the lower end of corrugated bulkhead, the shedder plates are to be weldedto the corrugation and the top plate of the transverse lower stool by one side penetration welds or equivalent.
2.4.3
The transverse lower stool side plating is to be connected to the transverse lower stool top plating and the inner
bottom plating by full penetration welds. Deep penetration welds may be accepted.
2.4.4
The supporting floors are to be connected to the inner bottom plating by full penetration welds. Deep penetration
welds may be accepted.
2.4.5
Generally, adequate groove angle between 40 and 60 degrees and root opening is to be taken and if necessary backgouging for both side welding is required.
2.5
Deep penetration weld
2.5.1
Deep penetration weld is defined as Fig. 2.
Fig. 2

Deep penetration weld

T

T

f

a

f

a

a

Root face ( f ): 3 mm to T/3 mm
Groove angle ( a ) : 40º to 60º

2.6Fillet welds
2.6.1 Kinds and size of fillet welds and their applications
Kinds and size of fillet welds for as-built thickness of abutting plating up to 50 mm are classed into 5 categories asgiven in Table 1 and their application to hull construction is to be as required by Table 2.
In addition, for zones a and b of side frames as shown in Ch 3, Sec 6, Fig 19, the weld throats are to berespectively 0.44t and 0.4t, where t is as-built thickness of the thinner of two connected members.

－405－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

Table 1CategorKinds of fillet

y
F0

F1

F2

welds

As-built thickness of(1)

abutting plate, t, in mm

Double continuoust

weld
Double continuous
weld
Double continuous
weldtDouble continuous
weldIntermittent weld

Length of fillet

Pitch, in(2), (3)welds, in mm

mm

0.7t

-

-

weld, in mm

100.5t + 1.0--

0.4t + 2.0

-

-

20

t

0.3t + 4.0

-

-

t

10

0.4t + 1.0--

t < 200.3t + 2.0

-

-

t

0.2t + 4.0

-

-

-

-

75

300

10
t
10
20
t

F4

Leg length of fillett < 201020F3Categories of fillet welds

10
20

10

0.3t + 1.0

t < 200.2t + 2.0t

0.1t + 4.0

100.5t + 1.0

t < 200.4t + 2.0t

0.3t + 4.0(1) t is as-built thickness of the abutting plate, in mm. In case of cross joint as specified in Fig. 1, t is the thinner
thickness of the continuous member and the abutting plate, to be considered independently for each abutting plate.
(2) Leg length of fillet welds is made fine adjustments corresponding to the corrosion addition tC specified in Ch3, Sec
3, Table 1 as follows:+ 1.0 mmfor tC > 5+ 0.5 mmfor 5 ³ tC > 4+ 0.0 mm
- 0.5 mmfor 4 ³ t C > 3
for tC £ 3(3) Leg length is rounded to the nearest half millimetre.

－406－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

Table 2Connection

Hull areaOf

unlessBoundary plating

F1

Brackets at ends of members

F1

Ordinary stiffener andDeep tank bulkheads

F3

collar plates

Web of primary supporting members and collar plates

F2

Plating (Except deep tank bulkhead)

F4

Face plates of built-up

At ends (15% of span)

F2

stiffeners

Elsewhere

F4

Web of ordinary
stiffener

otherwise

End of primary

specified insupporting members

the table(1)CategoryTo

Watertight plate

General,Application of fillet welds

and ordinary stiffeners

Deck plate, shell plate, inner bottom plate, bulkhead plate

F0

Deck plate, shell plate, inner bottom plate, bulkhead plate

F1

Bottom and inner bottom plating

F3

Shell plates in strengthened bottom forward

F1

Inner bottom plate and shell plate except the above

F2

Bottom and inner bottom plating

F3

without brackets
End of primary
supporting members
and ordinary stiffeners
with brackets
Ordinary stiffenerCenter girder
Side girder including
Bottom andintercostal plate

doubleShell plates and innerAt ends, on a length equal to twobottombottom plates

frame spaces

Floor

F2

Center girder and side girders in way of hopper tanks

F2

Elsewhere

F3

Center girder, inner bottom and shell plates

F2

Web stiffener

Floor and girder

F3

inner side in

Web of primarySide plating, inner side plating and web of primary

double side

supporting members

supporting members

Bracket on center
girderSide andF2

structure
Side frameof single
side
structure

Side frame and end
bracketTripping bracket
Strength

t

13

deck
t < 13
Other deck
Deck

Ordinary stiffener andintercostal girder

See Ch 3
Sec 6 Fig.
19

Side shell plate
Side shell plate and side frame
Side shell plating within 0.6LCSR-B midship

F1

Side shell plating

F1

Side shell plating

F2

Ordinary stiffeners

F4

Deck plating

F3

Deck platingof the hatch length
Elsewhere

Web stiffeners

penetration

Elsewhere

At corners of hatchways for 15%
Hatch coamings

F1
Deep

Coaming webs

－407－

F1
F2
F4

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

Table 2Connection

Hull area

bulkhead structure
Ordinary stiffenerTo
Boundaries

Swash bulkheads

Bulkhead plating
Shell plating, deck
plating, inner bottom
plating, bulkhead

Primary
supporting

Web platemembers(1)After peak

CategoryOf
Non-watertight

Bulkheads

Application of fillet welds (continued)

end brackets are fitted

F1

At end (15% of span)

F1

Elsewhere

F2

In tanks, and located within
0.125 LCSR-B from fore peak

Face plate

Internal members

At ends (25% of span), where no

F3

F2

Face area exceeds 65 cm2

F2

Elsewhere

F3

Boundaries and each other

F2

In way of main engine, thrust
Bed platebearing, boiler bearers and main

F1

generator engines
Seating

Girder and bracket

External bulkhead
Super-

Ordinary stiffeners

structure andEnd section ofdeck houses

ordinary stiffener andPrimary supporting
memberIn way of main engine and thrust

Girder plate

bearing

Inner bottom plate

In way of main engine and thrustand shellbearing

Deck

F1
F2

Side wall and deckAt end (15% of span)

F1
F3

plate

Elsewhere

F4 (2)

Without brackets
With bracket

Side wall and web of primary
supporting members

F1
F2

PillarPillarHeel and head

F1

Ventilator

Coaming

Deck

F1

Vertical frames forming main piece

F1

RudderRudder frame

Rudder plate

F3

Rudder frames except above

F2

Notes:(1) For Hatch cover, weld sizes F1, F2 and F3 instead of F0, F1 and F2, respectively, are to be used.
(2) Where the one side continuous welding is applied, the weld size F3 is to be applied.
(3) The interior bulkheads are not included in this category. The welding of the interior bulkheads is to be subjectedto the discretion of the Society.

2.6.2 Intermittent welds
Where double continuous fillet welds in lieu of intermittent welds are applied, leg length of fillet welds is to be ofcategory F3.
2.6.3 Size of fillet weld for abutting plating with small angle
Where the angle between an abutting plate and the connected plate is not 90 degrees as shown in Fig. 3, the size offillet welds for the side of larger angle is to be increased in accordance with the following formula:1¢
tl = tlæjö
2 sin çè2ø－408－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

where:
tl : Leg length of the fillet weld, in mm, as defined in 2.3.1

Fig. 3Connecting angle

2.6.4 Deep penetration welds
The leg length of fillet welds of deep penetration type may be reduced by 15% of that required in Table 1,
depending on the welding procedure test.
2.7
Lap joint welds
2.7.1 GeneralLap joint welds may be adopted in very specific cases subject to the approval of the Society. Lap joint welds may
be adopted for the followings:
・ peripheral connections of doublers
・ internal structural elements subject to very low stresses.
2.7.2 Fillet welds
Lap joints are to have the fillet size of category F1.
2.8
Slot welds
2.8.1 General
Slot welds may be adopted in very specific cases subject to the approval of the Society. However, slot welds ofdoublers on the outer shell and strength deck are not permitted within 0.6LCSR-B amidships.
2.8.2 Size of fillet welds
The slot welds are to have adequate shape to permit a thoroughly fused bead to be applied all around the bottomedge of the opening. The size of fillet welds is to be category F1 and spacing of slots is to be as determined by theSociety on a case by case basis.
3.

Connection details

3.1
Bilge keel connection
3.1.1
The intermediate flat, through which the bilge keel is connected to the shell, according to Ch 3, Sec 6, 6.5.2, is tobe welded to bilge plating and bilge keel.
3.1.2
The butt welds of the intermediate flat and bilge keel are to be full penetration and shifted from the shell butts.
The butt welds of the bilge plating and those of the intermediate flat are to be flush in way of crossing, respectively,
with the intermediate flat and with the bilge keel.
3.1.3
Along the longitudinal edges, the intermediate flat is to be continuously fillet welded with a throat thickness "a" of
0.3 times its thickness. At the ends of intermediate flat, the throat thickness "a" at the end faces is to be increased to
0.5 times the intermediate flat thickness but is to be less than the bilge plating thickness (see Fig. 4).
The welded transition at the end faces of the doubling plates to the plating should form with the latter an angle of
45 or less.

－409－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 2)

Bilge keel welding arrangementthabout 3hmin. 100

about 1.5br ³ 2tb

Fig. 4－410－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 3)

Section 3
1.

TESTING OF COMPARTMENTS

General1.1
Definitions
1.1.1 Shop primer
Shop primer is a thin coating applied after surface preparations and prior to fabrication as a protection against
corrosion during fabrication.
1.1.2 Protective coating
Protective coating is a final coating protecting the structure from corrosion.
1.1.3 Structural testing
Structural testing is a hydrostatic test carried out to demonstrate the tightness of the tanks and the structural
adequacy of the design. Where practical limitations prevail and hydrostatic testing is not feasible (for example when
it is difficult, in practice, to apply the required head at the top of tank), hydropneumatic testing may be carried out
instead. When hydropneumatic testing is performed, the conditions should simulate, as far as practicable, the actualloading of the tank.
1.1.4 Hydropneumatic testing
Hydropneumatic testing is a combination of hydrostatic and air testing, consisting in filling the tank with water up
to its top and applying an additional air pressure. The value of additional air pressure is at the discretion of theSociety, but is to be at least as defined in 2.2.
1.1.5 Leak testing
Leak testing is an air or other medium test carried out to demonstrate the tightness of the structure.
1.1.6 Hose testing
Hose testing is carried out to demonstrate the tightness of structural items not subjected to hydrostatic or leaktesting and to other compartments which contribute to the watertight integrity of the hull.
1.2
Application
1.2.1
The following requirements determine the testing conditions for:・ tanks, including independent tanks,
・ watertight or weathertight structures.
1.2.2
The purpose of these tests is to check the tightness and/or the strength of structural elements at time of ship
construction and on the occasion of major repairs.
1.2.3
Tests are to be carried out in the presence of the Surveyor at a stage sufficiently close to completion so that any
subsequent work not impair the strength and tightness of the structure.
2.

Testing methods

2.1
Structural testing
2.1.1
Structural testing may be carried out after application of the shop primer.
2.1.2
Structural testing may be carried out after the protective coating has been applied, provided that one of thefollowing two conditions is satisfied:・ all the welds are completed and carefully inspected visually to the satisfaction of the Surveyor prior to theapplication of the protective coating,・ leak testing is carried out prior to the application of the protective coating.
2.1.3
In absence of leak testing, protective coating should be applied after the structural testing of:－411－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 3)

・ all erection welds, both manual and automatic,
・ all manual fillet weld connections on tank boundaries and manual penetration welds.
2.2
Leak testing
2.2.1
Where leak testing is carried out, in accordance with Table 1, an air pressure of 0.15 10 5 Pa is to be applied
during the test.
2.2.2
Prior to inspection, it is recommended that the air pressure in the tank is raised to 0.20 10 5 Pa and kept at thislevel for about 1 hour to reach a stabilized state, with a minimum number of personnel in the vicinity of the tank, andthen lowered to the test pressure.
2.2.3
The Society may accept that the test is conducted after the pressure has reached a stabilized state at 0.20 10 5 Pa,
without lowering pressure, provided they are satisfied of the safety of the personnel involved in the test.
2.2.4
Welds are to be coated with an efficient indicating liquid.
2.2.5
A U-tube filled with water up to a height corresponding to the test pressure is to be fitted to avoid overpressure of
the compartment tested and verify the test pressure. The U-tube should have a cross section larger than that of thepipe supplying air.
In addition, test pressure is also to be verified by means of one master pressure gauge. The Society may accept
alternative means which are considered to equivalently reliable.
2.2.6
Leak testing is to be carried out, prior to the application of protective coating, on all fillet weld connections on tankboundaries, penetrations and erection welds on tank boundaries excepting welds may be automatic processes.
Selected locations of automatic erection welds and pre-erection manual or automatic welds may be required to be
similarly tested at the discretion of the Surveyor taking account of the quality control procedures operating in the
shipyard. For other welds, leak testing may be carried out, after the protective coating has been applied, provided thatthese welds were carefully inspected visually to the satisfaction of the Surveyor.
2.2.7
Any other recognized method may be accepted to the satisfaction of the Surveyor.
2.3
Hose testing
2.3.1
When hose testing is required to verify the tightness of the structures, as defined in Table 1, the minimum pressurein the hose, at least equal to 2.0 105 Pa, is to be applied at a maximum distance of 1.5 m. The nozzle diameter is not
to be less than 12 mm.
2.4
Hydropneumatic testing
2.4.1
When hydropneumatic testing is performed, the same safety precautions as for leak testing are to be adopted.
2.5
Other testing methods
2.5.1
Other testing methods may be accepted, at the discretion of the Society, based upon equivalency considerations.
3.

Testing requirements

3.1
General
3.1.1
General testing requirements for testing are given in Table 1.

－412－

Item

－413－

Watertight doors below freeboard or

8

Shaft tunnel clear of deep tanks

Shell doors

Watertight hatchcovers of tanks

Watertight hatchcovers and closing

10

11

12

13

appliances

Double plate rudder9bulkhead deck

Watertight bulkheads

7

Leak testing

Aft peak not used as tank

Hose testing

Hose testing

Hose testing

Hose testing

Leak testing

Refer to SOLAS Ch II-1 Reg.18

Refer to SOLAS Ch II-1 Reg.14 (4)Structural testing (3)Refer to SOLAS Ch II-1 Reg.14

Fore peak not used as tank

Cofferdams

Structural testing

Structural testing (1)Fore peak and after peak used as tank

6

5

Ballast holds

Structural testing

Fuel oil tanks

4

Structural testing (1)Tank bulkheads, deep tanks

3

Structural testing

Double side tanks(1)

2

Structural testing (1)Type of testing

Double bottom tanks

Structure to be tested

1

numberTable 1・2.4 m head of water above highest point of tank

The greater of the following:・head of water up to the top of overflow

・2.4 m head of water above highest point of tank

The greater of the following:・head of water up to the top of overflow

・head of water up to the top of hatch coaming

The greater of the following:・head of water up to the top of overflow

・setting pressure of the safety relief valves, where relevant

・2.4 m head of water above highest point of tank

The greater of the following: (2)・head of water up to the top of overflow

・2.4 m head of water above highest point of tank

The greater of the following:・head of water up to the top of overflow

・head of water up to the bulkhead deck

The greater of the following:・head of water up to the top of overflow

Structural test pressure

General testing requirements

after the stern tube has been fitted

Tank of the after peak carried out

one side

Tank boundaries tested from at least

one side

Tank boundaries tested from at least

one side

Tank boundaries tested from at least

Remarks

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 3)

(4)

(3)

(2)

Structural testing

Structural testing

Structural testingType of testing

Ballast pump maximum pressure

Head of water up to the top of overflow, but not less than 0.9 m

Head of water up to the top

Structural test pressure

Remarksa careful visual inspection of all the crossings and weld joints; where necessary, dye penetrant test or ultrasonic test may be required.

When hose test cannot be performed without damaging possible outfitting (machinery, cables, switchboards, insulation, etc.) already installed, it may be replaced, at the Society discretion, by

techniques and the welding procedures adopted.

Leak or hydropneumatic testing may be accepted under the conditions specified in 2.2 when, at the Society discretion, the latter is considered significant also in relation to the construction

taken at the top of hatch.

Where applicable, the highest point of tank is to be measured to the deck and excluding hatches. In holds for liquid cargo or ballast with large hatch covers, the highest point of tanks is to be

structurally tested.

in tankers and combination carriers and tanks for segregated cargoes or pollutants. If the structural test reveals weakness or severe faults not detected by the leak test, all tanks are to beapproval of the design. In general, structural testing need not be repeated for subsequent vessels of series of identical newbuildings. This relaxation does not apply to cargo space boundaries

Leak or hydropneumatic testing may be accepted under the conditions specified in 2.2, provided that at least one tank for each type is structurally tested, to be selected in connection with theBallast ducts(1)

Independent tanks

16

bulkhead

Chain locker, located aft of collision

Structure to be tested

15

14

numberItem2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 11 Section 3)－414－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 12 Section 1)

Chapter 12
Section 1

ADDITIONAL CLASS NOTATIONSGRAB ADDITIONAL CLASS NOTATION

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
MGR : Mass of unladen grab, in tonss
: Spacing, in m, of ordinary stiffeners, measured at mid-span

1.

Basic concepts

1.1
Application
1.1.1
The additional class notation GRAB [X] is assigned, in accordance with Ch 1, Sec 1, 3.2, to ships with holds
designed for loading/unloading by grabs having a maximum specific weight up to [X] tons, in compliance with therequirements of this Section.
1.1.2
It is to be noted that this additional class notation does not negate the use of heavier grabs, but the owner andoperators are to be made aware of the increased risk of local damage and possible early renewal of inner bottom
plating if heavier grabs are used regularly or occasionally to discharge cargo.
2.

Scantlings

2.1
Plating
2.1.1
The net thickness of plating of inner bottom, hopper tank sloping plate, transverse lower stool, transverse bulkhead
plating and inner hull up to a height of 3.0m above the lowest point of the inner bottom, excluding bilge wells, is tobe taken as the greater of the following values:
・ t, as obtained according to requirements in Ch 6 and Ch 7・ tGR, as defined in 2.1.2 and 2.1.3.
2.1.2
The net thickness tGR, in mm, of the inner bottom plating is to be obtained from the following formula:t GR = 0.28(M GR + 50) sk

2.1.3
The net thickness tGR, in mm, of hopper tank sloping plate, transverse lower stool, transverse bulkhead plating andinner hull up to a height of 3.0m above the lowest point of the inner bottom, excluding bilge wells, is to be obtained
from the following formula:t GR = 0.28(M GR + 42) sk－415－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 13 Section 1)

Chapter 13

SHIPS IN OPERATION, RENEWAL CRITERIA

Section 1
1.

MAINTENANCE OF CLASSGeneral1.1
Application
1.1.1
The survey requirements for the maintenance of class of bulk carriers covered by this Part are given in Part B.
Thickness measurements are a major part of surveys to be carried out for the maintenance of class, and the analysis ofthese measurements is a prominent factor in the determination and extent of the repairs and renewals of the ship s
structure.
1.1.2 (Void)
1.1.3 (Void)
1.2
Definitions
1.2.1 Local corrosion
Local corrosion is pitting corrosion, grooving, edge corrosion, necking effect or other corrosions of very local aspect.
1.2.2 Substantial corrosion
Substantial corrosion is an extent of corrosion such that assessment of the corrosion pattern indicates a gauged (ormeasured) thickness between trenewal and trenewal + treserve.
1.2.3 Deck zone
The deck zone includes all the following items contributing to the hull girder strength above the horizontal strake ofthe topside tank or above the level corresponding to 0.9D above the base line if there is no topside tank:・ strength deck plating・ deck stringer
・ sheer strake・ side shell plating
・ top side tank sloped plating, including horizontal and vertical strakes
・ longitudinal stiffeners connected to the above mentioned platings.
1.2.4 Bottom zone
The bottom zone includes the following items contributing to the hull girder strength up to the upper level of thehopper sloping plating or up to the inner bottom plating if there is no hopper tank:・ keel plate・ bottom plating・ bilge plate・ bottom girders
・ inner bottom plating・ hopper tank sloping plating・ side shell plating
・ longitudinal stiffeners connected to the above mentioned platings.
1.2.5 Neutral axis zone
The neutral axis zone includes the plating only of the items between the deck zone and the bottom zone, as forexample:・ side shell plating・ inner hull plating, if any－416－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 13 Section 2)

Section 2

ACCEPTANCE CRITERIA

Symbols
For symbols not defined in this Section, refer to Ch 1, Sec 4.
: Renewal thickness; Minimum allowable thickness, in mm, below which renewal of structuraltrenewal
members is to be carried out
trenewal = tas_built tC tvoluntary_addition: Reserve thickness; Thickness, in mm, to account for anticipated thickness diminution that may occur
treserve
during a survey interval of 2.5 year. (treserve = 0.5 mm)
tC: Corrosion addition, in mm, defined in Ch 3, Sec3
: As built thickness, in mm, including tvoluntary_addition, if any
tas_built
tvoluntary_addition : Voluntary thickness addition; Thickness, in mm, voluntarily added as the Owner s extra margin for
corrosion wastage in addition to tC: Gauged thickness, in mm, on one item, i.e. average thickness on one item using the various
tgaugedmeasurements taken on this same item during periodical ship s in service surveys.

1.

Local strength criteria

1.1
Application
1.1.1
The items to be considered for the local strength criteria are those defined in the relevant requirement of Part B.
1.2
Renewal thickness for corrosion other than local corrosion
1.2.1
For each item, steel renewal is required when the gauged thickness tgauged is less than the renewal thickness, as
specified in the following formula:tgauged < trenewal,
Where the gauged thickness tgauged is such as:trenewal < tgauged < trenewal + treservecoating applied in accordance with the coating manufacturer s requirements or annual gauging may be adopted as analternative to the steel renewal. The coating is to be maintained in good condition.
1.3
Renewal thickness for local corrosion
1.3.1
If pitting intensity in an area where coating is required, according to Ch 3, Sec 5, is higher than 15% (see Fig. 1),
thickness measurements are to be performed to check the extent of pitting corrosion. The 15% is based on pitting or
grooving on only one side of a plate.
In cases where pitting is exceeding 15%, as defined above, an area of 300 mm or more, at the most pitted part of theplate, is to be cleaned to bare metal and the thickness is to be measured in way of the five deepest pits within the cleaned
area. The least thickness measured in way of any of these pits is to be taken as the thickness to be recorded.
The minimum remaining thickness in pits, grooves or other local areas as defined in Ch 13, Sec 1, 1.2.1 is to begreater than:・ 75% of the as-built thickness, in the frame and end brackets webs and flanges
・ 70% of the as-built thickness, in the side shell, hopper tank and topside tank plating attached to the each side frame,over a width up to 30 mm from each side of it,
without being greater than trenewal.

－417－

2015 Rules for the Survey and Construction of Steel Ships (Part CSR-B Chapter 13 Section 2)

Fig. 1

Pitting intensity diagrams (from 5% to 25% intensity)

1.4
Global strength criteria
1.4.1 Items for the global strength criteria
The items to be considered for the global strength criteria are those of the deck zone, the bottom zone and the neutral
axis zone, as defined in Ch 13, Sec 1, 1.2.
1.4.2 Renewal thickness
The global strength criteria is defined by the assessment of the bottom zone, deck zone and neutral axis zone, asdetailed below.
a) bottom zone and deck zone:
The current hull girder section modulus determined with the thickness measurements is not to be less than 90% of
the section modulus calculated according to Ch 5, Sec 1 with the gross offered thicknesses.
Alternatively, the current sectional areas of the bottom zone and of the deck zone which are the sum of the gauged
items area of the considered zones, are not to be less than 90% of the sectional area of the corresponding zones
determined with the gross offered thicknesses.
b) neutral axis zone:
The current sectional area of the neutral axis zone, which is the sum of the gauged platings area of this zone, is not
to be less than 85% of the gross offered sectional area of the neutral axis zone.
If the actual wastage of all items, of a given transverse section, which contribute to the hull girder strength is lessthan 10% for the deck and bottom zones and 15% for the neutral axis zone, the global strength criteria of thistransverse section is automatically satisfied and its checking is no more required.

－418－

MAJOR CHANGES AND EFFECTIVE DATES
Amendments to Part CSR-B of the RULES FOR THE SURVEY AND CONSTRUCTION OF STEEL SHIPS
made between 1 March 2014 and 28 February 2015 and their effective dates are as follows:

I

AMENDMENTS ON 27TH FEBRUARY 2015 (Rule No.16)
Chapter 1
Section 1

Paragraph 1.1.1 has been amended.

EFFECTIVE DATE AND APPLICATION
1.

The effective date of the amendments is 1 July 2015.

2.

Notwithstanding the amendments to the Rules, the current requirements may apply to ships
for which the date of contract for construction* is before the effective date.
* contract for construction is defined in the latest version of IACS Procedural Requirement(PR) No.29.
IACS PR No.29 (Rev.0, July 2009)

1.
2.

3.
4.

The date of contract for construction of a vessel is the date on which the contract to build the vessel is signed between the prospective
owner and the shipbuilder. This date and the construction numbers (i.e. hull numbers) of all the vessels included in the contract are to be
declared to the classification society by the party applying for the assignment of class to a newbuilding.
The date of contract for construction of a series of vessels, including specified optional vessels for which the option is ultimately
exercised, is the date on which the contract to build the series is signed between the prospective owner and the shipbuilder.
For the purpose of this Procedural Requirement, vessels built under a single contract for construction are considered a series of vessels
if they are built to the same approved plans for classification purposes. However, vessels within a series may have design alterations
from the original design provided:(1) such alterations do not affect matters related to classification, or(2) If the alterations are subject to classification requirements, these alterations are to comply with the classification requirements ineffect on the date on which the alterations are contracted between the prospective owner and the shipbuilder or, in the absence of thealteration contract, comply with the classification requirements in effect on the date on which the alterations are submitted to theSociety for approval.
The optional vessels will be considered part of the same series of vessels if the option is exercised not later than 1 year after the contract
to build the series was signed.
If a contract for construction is later amended to include additional vessels or additional options, the date of contract for construction
for such vessels is the date on which the amendment to the contract, is signed between the prospective owner and the shipbuilder. The
amendment to the contract is to be considered as a new contract to which 1. and 2. above apply.
If a contract for construction is amended to change the ship type, the date of contract for construction of this modified vessel, or
vessels, is the date on which revised contract or new contract is signed between the Owner, or Owners, and the shipbuilder.

Note:This Procedural Requirement applies from 1 July 2009.

14-391

RULES FOR THE SURVEY AND CONSTRUCTION
OF STEEL SHIPSPart CSR-B

Common Structural Rules for Bulk Carriers

Rules for the Survey and Construction of Steel Ships
Part CSR-B
2015 AMENDMENT NO.1

Rule No.16

27th February 2015

Resolved by Technical Committee on 2nd February 2015
Approved by Board of Directors on 23rd February 2015

NIPPON KAIJI KYOKAI

Rule No.16
27th February 2015
AMENDMENT TO THE RULES FOR THE SURVEY AND CONSTRUCTION OF STEELSHIPS“Rules for the survey and construction of steel ships” has been partly amended as follows:Part CSR-B COMMON STRUCTURAL RULES FOR BULKCARRIERS
Chapter 1

GENERAL PRINCIPLES

Section 1
1.

General

1.1

Structural requirements

APPLICATION

Paragraph 1.1.1 has been amended as follows.
1.1.1
This Part applies to ships classed with the Society and contracted for construction on or after 1
April 2006 but before 1 July 2015.
Note: The "contracted for construction" means the date on which the contract to build theship is signed between the prospective owner and the shipbuilder. For further details
regarding the date of "contracted for construction", refer to IACS Procedural
Requirement (PR) No.29.

1EFFECTIVE DATE AND APPLICATION1.
2.

The effective date of the amendments is 1 July 2015.
Notwithstanding the amendments to the Rules, the current requirements may apply toships for which the date of contract for construction* is before the effective date.
* “contract for construction” is defined in the latest version of IACS Procedural
Requirement (PR) No.29.
IACS PR No.29 (Rev.0, July 2009)

1.
2.

3.
4.

The date of “contract for construction” of a vessel is the date on which the contract to build the vessel is signed between theprospective owner and the shipbuilder. This date and the construction numbers (i.e. hull numbers) of all the vessels included in thecontract are to be declared to the classification society by the party applying for the assignment of class to a newbuilding.
The date of “contract for construction” of a series of vessels, including specified optional vessels for which the option is ultimately
exercised, is the date on which the contract to build the series is signed between the prospective owner and the shipbuilder.
For the purpose of this Procedural Requirement, vessels built under a single contract for construction are considered a “series ofvessels” if they are built to the same approved plans for classification purposes. However, vessels within a series may have design
alterations from the original design provided:(1) such alterations do not affect matters related to classification, or(2) If the alterations are subject to classification requirements, these alterations are to comply with the classification requirements ineffect on the date on which the alterations are contracted between the prospective owner and the shipbuilder or, in the absence of
the alteration contract, comply with the classification requirements in effect on the date on which the alterations are submitted to
the Society for approval.
The optional vessels will be considered part of the same series of vessels if the option is exercised not later than 1 year after thecontract to build the series was signed.
If a contract for construction is later amended to include additional vessels or additional options, the date of “contract for
construction” for such vessels is the date on which the amendment to the contract, is signed between the prospective owner and the
shipbuilder. The amendment to the contract is to be considered as a “new contract” to which 1. and 2. above apply.
If a contract for construction is amended to change the ship type, the date of “contract for construction” of this modified vessel, or
vessels, is the date on which revised contract or new contract is signed between the Owner, or Owners, and the shipbuilder.

Note:This Procedural Requirement applies from 1 July 2009.

2