Annex Unified Interpretations of SOLAS Chapter II-1
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1539/Rev.1 Unified Interpretations of SOLAS Chapters II-1 and Safe Return to Port Requirements for Flooding Detection Systems (4 July 2019) - Annex Unified Interpretations of SOLAS Chapter II-1

Annex Unified Interpretations of SOLAS Chapter II-1

Regulation 2.21 Definition of the term "Lightweight"

1 The weight of mediums on board for the fixed fire-fighting systems (e.g. freshwater, CO2, dry chemical powder, foam concentrate, etc.) should be included in the lightweight and lightship condition.

Regulation 3-2 Protective coatings of dedicated seawater ballast tanks in all types of ships and double-side skin spaces of bulk carriers

2 The following tanks should not be considered to be dedicated seawater ballast tanks and should, therefore, be exempted from the application and requirements of the Performance standard for protective coatings for dedicated seawater ballast tanks in all types of ships and double-side skin spaces of bulk carriers (resolution MSC.215(82)), provided the coatings applied in the tanks described in sub-paragraphs .2 and .3 below are confirmed by the coating manufacturer to be resistant to the media stored in these tanks and provided such coatings are applied and maintained according to the coating manufacturer's procedures.

  • .1 ballast tanks identified as "Spaces included in Net Tonnage" in the International Tonnage Certificate (1969);

  • .2 seawater ballast tanks in passenger ships also designated for the carriage of grey water or black water; and

  • .3 seawater ballast tanks in livestock carriers also designated for the carriage of livestock dung.

Regulation 7-2 Calculation of the factor si

3 In applying θv, openings which cannot be or are incapable of being closed weathertight include ventilators (complying with regulation 19(4) of the International Convention on Load Lines, 1966) that for operational reasons have to remain open to supply air to the engine-room, emergency generator room or closed ro-ro and vehicle spaces (if the same is considered buoyant in the stability calculation or protecting openings leading below) for the effective operation of the ship. Where it is not technically feasible to treat some closed ro-ro and vehicle space ventilators as unprotected openings, Administrations may allow an alternative arrangement that provides an equivalent level of safety.

Regulation II-1/22-1 Flooding detection systems for passenger ships carrying 36 or more persons constructed on or after 1 July 2010footnote

"A flooding detection system for watertight spaces below the bulkhead deck shall be provided based on the guidelines developed by the Organization.footnote

Regulation II-2/21.4 Safe return to portfootnote

"When fire damage does not exceed the casualty threshold indicated in paragraph 3, the ship shall be capable of returning to port while providing a safe area as defined in regulation 3. To be deemed capable of returning to port, the following systems shall remain operational in the remaining part of the ship not affected by fire:


.13 flooding detection systems; and (...)

Guidelines for flooding detection systems on passenger ships (MSC.1/Circ.1291)

"7 Any watertight spaces that are separately equipped with a liquid level monitoring system (such as fresh water, ballast water, fuel, etc.), with an indicator panel or other means of monitoring at the navigation bridge (and the safety centre if located in a separate space from the navigation bridge), are excluded from these requirements."


For passenger ships carrying 36 or more persons and subject to SOLAS regulation II-1/8-1, the Safe Return To Port (SRTP) requirements of SOLAS regulation II-2/21.4 apply to both:

  • .1 the flooding detection systems in the spaces as defined in paragraph 6 of MSC.1/Circ.1291; and

  • .2 the liquid level monitoring systems, which are used as, or replace, the flooding detection systems, as specified in paragraph 7 of MSC.1/Circ.1291.

Therefore, for systems noted in sub-paragraph .2 above, the phrase "excluded from these requirements" in paragraph 7 of MSC.1/Circ.1291 is not an exclusion from the general provision in SOLAS regulation II-2/21.4.13 (remain operational in the event of fire). This exclusion pertains only to the detailed provisions in MSC.1/Circ.1291.

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