Regulation 9 - Double bottoms in passenger ships and cargo ships other than tankers
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1226 – Interim Explanatory Notes to the SOLAS Chapter II-1 Subdivision and Damage Stability Regulations – (15 January 2007) - Annex - Interim Explanatory Notes to the SOLAS Chapter II-1 Subdivision and Damage Stability Regulations - Part B - Guidance on Individual Regulations - Regulation 9 - Double bottoms in passenger ships and cargo ships other than tankers

Regulation 9 - Double bottoms in passenger ships and cargo ships other than tankers

Parent topic: Part B - Guidance on Individual Regulations

Paragraph 2

 If an inner bottom is located higher than the partial subdivision draught dp , this should be considered an unusual arrangement in accordance with paragraph 7.

Paragraph 9

 For the purpose of identifying "large lower holds", horizontal surfaces having a continuous deck area greater than approximately 30% in comparison with the waterplane area at subdivision draught should be taken located anywhere in the affected area of the ship. For the alternative bottom damage calculation, a vertical extent of B/10 or 3 m, whichever is less, should be assumed.

 The increased minimum double bottom height of not more than B/10 or 3 m, whichever is less, for passenger ships with large lower holds, is applicable to holds in direct contact with the double bottom. Typical arrangements of ro-ro passenger ships may include a large lower hold with additional tanks between the double bottom and the lower hold, as shown in the figure below. In such cases, the vertical position of the double bottom required to be B/10 or 3 m, whichever is less, should be applied to the lower hold deck, maintaining the required double bottom height of B/20 or 2 m, whichever is less (but not less than 760 mm).

Typical arrangement of a modern ro-ro passenger ferry
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