M46

M46
M46(2009)(1982)(cont)(Rev.1June 2002)(Rev.2Dec 2018)(Rev.3Aug 2023)

Ambient conditions – Inclinations and Ship
Accelerations and Motions
M46.1

GeneralThe ambient conditions specified under M46.2 and M46.3 are to be applied to the layout,
selection and arrangement of all shipboard machinery, equipment and appliances (addressedin this UR) to ensure proper operation.

Note:
1. The requirements of UR M46 Rev.2 are to be uniformly implemented by IACS Societies on
ships contracted for construction on or after 1 January 2020.
2. The requirements of UR M46 Rev.3 are to be uniformly implemented by IACS Societies on
ships contracted for construction on or after 1 January 2025.
23. 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. 1982/Rev.3 2023

M46

M46
(cont)

M46.2

Inclinations

Inclinations applied to respective components are as follows.
Installations, components
Main and auxiliary machinery
Safety equipment,e.g.
emergency power installations,emergency fire pump and their devices
Switch gear, electrical and electronic
appliances1

Angle of inclination [°]2
Athwartships
Fore-and-aft
staticdynamic
staticdynamic
15

22.5

54

7.5

22.53

22.53

10

10

and remote-control systems
Notes:
1. No undesired switching operations or operational changes are to occur.
2. Athwartships and fore-and-aft inclinations may occur simultaneously.
3. In ships for the carriage of liquefied gases and of chemicals, the emergency power
supply must also remain operable with the ship flooded to a final athwartships
inclination up to maximum of 30°.
4. Where the length of the ship exceeds 100m, the fore-and-aft static angle of inclination
may be taken as 500/L degrees where L = length of the ship, in metres, as defined in
UR S2.
The Society may consider deviations from these angles of inclination, taking into
consideration the type, size and service conditions of the ship.
M46.3

Shipboard accelerations

3.1
Main propulsion and steering machinery and auxiliary machinery that is essential tothe propulsion and steering, and the safety of the ship shall be capable of operation under theeffects of acceleration and motions.
3.2
The requirements in M46.4 to M46.6 apply where documented evidence ofequipment suitability is specifically required by other relevant URs for such equipment orrequested by the Classification Society.
M46.4

Documentation

4.1
For ships subject to the SOLAS Convention, ship builders are to identify anddocument the ship accelerations and motions periods to which machinery and equipment
might be subjected to. The expected accelerations and ship motions periods are to be within
machinery and equipment manufacturers requirements. The estimations are to consider
vessel type, machinery or equipment location and expected service conditions.
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IACS Req. 1982/Rev.3 2023

M46M46(cont)M46.5

Evaluation of equipment suitability

5.1
Machinery and equipment manufacturers are to submit evidence to the Classification
Society that their machinery or equipment can operate under the required static and dynamic
conditions stated in M46.2 and at least at the levels of shipboard accelerations as stated inM46.4 and/or specified in the relevant URs. Documentation of satisfactory performance shalltake the form of:M46.6.1

Report of testing under representative conditions; or.2

Report of theoretical verification using recognised computational techniques
accompanied by detailed and relevant validation data: or.3

Historical data which provides relevant demonstration of satisfactory experiencein service.

Installation and operation

6.1
Machinery and equipment manufacturers are to submit details of the requirements/recommendations for installation of the machinery and equipment onboard to ensuresatisfactory operation in service under the required static and dynamic conditions as
described in M46.2 and at least at the levels of shipboard accelerations as stated in M46.4
and/or specified in the relevant URs.
Note: Consideration should be given for positioning machinery in order to minimize thedynamic load on bearings due to ship motion.
6.2
Shipbuilders are to submit details demonstrating that the installation of themachinery and equipment onboard is in accordance with manufacturer’s requirements/recommendations.

End ofDocument

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IACS Req. 1982/Rev.3 2023