Guidance

MGN 692 (M) Revised notes to the SOLAS Chapter II-1 subdivision and damage stability regulations

Published 19 December 2023

Summary

This Note provides the consolidated text of the Revised Explanatory Notes to the SOLAS Chapter II-1 Subdivision and Damage Stability Regulations as set out in MSC.429(98)/Rev.2.

1. Introduction/background

1.1 The International Maritime Organization, by Resolution MSC.216(82), introduced revised requirements for subdivision and damage stability. These requirements entered into force for passenger ships and dry cargo ships built on or after 1 January 2009. Known as the SOLAS 2009 amendments, MSC.216(82) included amendments to SOLAS Chapter II-1 Parts A (General), B (Subdivision and Stability), B-1 (Stability), B-2 (Subdivision, Watertight and Weathertight Integrity), B-3 (Subdivision Load Line Assignment for Passenger Ships), B-4 (Stability Management).

1.2 The SOLAS 2009 amendments replaced the deterministic damage stability and subdivision regulations for passenger ships in force prior to 1 January 2009 (commonly referred to as SOLAS 90) with a new probabilistic damage stability calculation procedure, removing  concepts such as floodable and permissible length, factor of subdivision, criterion of service and margin line.

1.3 For dry cargo ships of 80 metres in length and above, the previous probabilistic damage stability calculations in SOLAS 90 Part B-1, Regulations 25-1 to 25-10 were harmonised with those for passenger ships, with all being accompanied by a set of explanatory notes (introduced in IMO Resolution MSC.281(85)). IMO Resolution A.265(VIII) was also replaced which, since its introduction in 1973, had been considered as a probabilistic equivalent to all the deterministic SOLAS subdivision and damage stability regulations for passenger ships in force between 1973 and 31 December 2008.

1.4 Since 1 January 2009, further amendments were found to be necessary to SOLAS 2009. These were finally introduced by IMO Resolutions MSC.421(98) (adopted on 15 June 2017) and MSC.436(99) (adopted on 24 May 2018)  which came into force on 1 January 2020. These are known as the SOLAS 2020 amendments, applicable to ships constructed on or after that date.

1.5 At the same time as the amendments to the SOLAS 2009 regulations appeared, the first amendments to the accompanying explanatory notes were made and appeared in IMO Resolution MSC.429(98), which was adopted on 9 June 2017 and took effect on 1 January 2020.

1.6 Further revisions to the 2020 explanatory notes were agreed and a consolidated version including all the amendments made to the explanatory notes since 2009 was approved and adopted by IMO at MSC 102 under Resolutions MSC.429(98)/Rev.1 and  MSC.429(98)/Rev.2, with Rev.1 being revoked by Rev.2 on 1 January 2024. Thus, Rev.2 aligns with the new requirements in SOLAS Chapter II-1 introduced by IMO Resolution MSC.474(102) with the same entry into force date of 1 January 2024.

1.7 Please note that MSC.474(102) is given automatic effect in UK law in accordance with the ambulatory reference provision in regulation 6 of the Merchant Shipping (Cargo and Passenger Ship Construction and Miscellaneous Amendments) Regulations 2023.

More information

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