S3S3
S3S3(1973)(1973)

Strength of End Bulkheads of Superstructures
and Deckhouses(1973)(cont)(Rev.1May 2010)
S3.1 Scope(Rev.2June 2023)
The following proposal applies to bulkheads forming the only protection for openings as perRegulation 18 of LLC 1966 and for accommodations. These requirements define minimum
scantlings based upon local lateral loads and it may be required that they be increased inindividual cases. Scantlings of tiers not specifically mentioned in this proposal are left to thediscretion of individual Classification Societies.
This UR does not apply to CSR Bulk Carriers.

Note:
1.

Changes introduced in Rev.2 are to be uniformly implemented by IACS Members forships contracted for construction on or after 1 July 2024.

2.

The “contracted for construction” date means the date on which the contract to build thevessel is signed between the prospective owner and the shipbuilder. For further details
regarding the date of “contract for construction”, refer to IACS Procedural Requirement(PR) No. 29.

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IACS Req. 1973/Rev.2 2023

S3

S3(cont)

S3.2

p=Design pressure heada(bf − y )c100

wherep= design pressure in N/mm2 (MPa)a = 2 .0 +L1for lowest tier of unprotected fronts
120

The lowest tier is normally that tier which is directly situated above the uppermost continuous
deck to which the rule depth D is to be measured. However, where the freeboard isexcessive, it may be left to each individual Classification Society to define this tier as anupper tier. It is recommended that 'excessive freeboard' is that which exceeds the minimum
tabular freeboard by more than one standard superstructure height.

a = 1 .0 +L1120

for 2nd tier of unprotected fronts

a = 0 .5 +L1150

for 3rd tier of unprotected fronts andfor sides and protected fronts

a = 0 .7 +L1x− 0 .81000
Lfor aft ends aft of amidships

a = 0 .5 +L1x− 0 .41000
L

for aft ends forward of amidships

L, L1 = length of ships in metres, L1 need not be taken greater than 300 m

 x L − 0.45 
b = 1.0 + +
C0.
2
 b

2

 x L − 0.45 
b = 1.0 + 1.5
 C b + 0 .2 for x / L ≤ 0.452for x / L > 0.45

0.60 < Cb < 0.80
Cb = block coefficient,when determining aft ends forward of amidships, Cb need not be taken less than 0.80
x= distance in metres between bulkhead considered and AP
When determining sides of a deckhouse, the deckhouse is to be subdivided into partsof approximately equal length, not exceeding 0,15L each and x is to be taken as thedistance between AP and the centre of each part considered.

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IACS Req. 1973/Rev.2 2023

S3S3(cont)f =2
L − L / 300   L  − 1 − e  for L < 150 m10
  150  

f =L − L / 300e10for 150 m < L < 300 m

f = 11.03
yfor L > 300 m= vertical distance in metres from summer waterline to midpoint of stiffener spanb' c =  0 .3 + 0 .7 B' = breadth of deckhouse at the position consideredb'B' = actual maximum breadth of ship on the exposed weather deck at the position
considered
For exposed parts of machinery casings c is not to be taken less than 1.0
The design pressure p is not to be taken less than the minimum values given in Table 1.
Table 1p (N/mm2 or MPa)

S3.3L(m)Lowest tier of unprotected
frontsElsewhereL ≤ 500.030.015

50 < L < 250

0.025 + 10-4L

0.0125 + 0.5 x 10-4L

L ≥ 250

0.05

0.025

Stiffener modulus

W = 350sl 2 p
where
W = stiffener modulus (cm3)s= spacing of stiffeners (m), measured along the platingl= unsupported span (m), which is to be taken as the ’tween deck height lmin = 2.0 mp= pressure in N/mm2 (MPa) as defined above.

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IACS Req. 1973/Rev.2 2023

S3S3(cont)

The section modulus of house side stiffeners need not be greater than that of side frames on
the deck situated directly below, taking account of spacing and span.
These requirements assume the webs of lower tier stiffeners to be efficiently welded to thedecks.
Scantlings for other types of end connections may be specially considered.
S3.4

Thickness of platingt = 30s p
wheret= thickness of plating (mm), not less than the minimum thickness as follows:tmin = 5.0 + L1/100 for lowest tier4.0 + L1/100 for upper tiers, but not less than 5.0 mm

For ships with L1<65m, the minimum thickness of plating should be as follows:tmin = 5mm for the lowest unprotected front
4mm for all other casess and p are as defined above.
When determining p, y is to be measured to middle of the plate field.

End ofDocument

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IACS Req. 1973/Rev.2 2023