2.4 Buoyancy and Stability Following Damage
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Statutory Documents - IMO Publications and Documents - International Codes - DSC Code - Code of Safety for Dynamically Supported Craft – Resolution A.373(X) - Chapter 2 - Buoyancy, Stability and Subdivision - 2.4 Buoyancy and Stability Following Damage

2.4 Buoyancy and Stability Following Damage

  2.4.1 Following any of the postulated damages detailed in 2.4.4 and 2.4.5, the craft in still water should have sufficient buoyancy and positive stability to simultaneously ensure that in the displacement mode:

  • (a) the final waterline is at least 76 millimetres below the level of any opening where progressive flooding could take place:

  • (b) the angle of inclination of the craft from the horizontal does not exceed 8° in any direction for all permitted cases of loading and for such uncontrolled passenger movements as are likely in emergency conditions. The Administration may permit angles of inclination up to 16° immediately after damage but quickly reducing to 12° provided that:

    • (i) suitable handholds and efficient non-slip deck surfaces are provided; and

    • (ii) it is impracticable to restrict the angle of heel to 8°.

    In exceptional cases the Administration may permit larger inclinations after damage provided the angle is quickly reduced to 12° and the provisions of sub-paragraphs (b) (i) and (ii) of this paragraph are satisfied;

  • (c) flooding of passenger compartments or escape routes will not significantly impede the evacuation of passengers;

  • (d) the Administration should be satisfied that the range of residual stability after damage is adequate.

  2.4.2 Following any of the postulated damage outlined in 2.4.4 and 2.4.5, the Administration should be satisfied that all reasonable and practicable steps have been taken to ensure that the craft, in the worst intended conditions, will have sufficient buoyancy and positive stability to remain afloat for at least 30 minutes or three times the demonstrated evacuation time plus 7 minutes whilst simultaneously ensuring that in the displacement mode:

  • (a) any flooding of passenger compartments or escape routes will not significantly impede the evacuation of passengers; and

  • (b) essential emergency equipment, emergency radios, power supplies and public address systems needed for organizing the evacuation remain accessible and operational.

  2.4.3 Any damage of a lesser extent than that postulated in 2.4.4 and 2.4.5 which would result in a more severe condition should also be investigated. The shape of the damage should be assumed to be parallelepiped.

  2.4.4 The following side damages are to be assumed anywhere on the periphery of the craft:

  • (a) the length of damage should be 0.1L, or 3 metres + 0.03L, or 11 metres, whichever is the least;

  • (b) the depth of penetration into the craft should be: 0.2B or 5 metres, whichever is less.

    However, where the craft is fitted with inflated skirts or with non-buoyant side structures, the depth of penetration should be at least 0.12 of the width of the main buoyancy hull or tank structure;

  • (c) the vertical extent of damage should be taken for the full depth of the craft.

  2.4.5 Bottom damages are to be assumed anywhere on the bottom of the craft as follows:

  • (a) the length of damage in the fore and aft directions should be:

    0.1L, or 3 metres + 0.03L. or 11 metres, whichever is the least;

  • (b) the width of damage should be:

    0.2B or 5 metres, whichever is less, except that in the case of a catamaran or an air-cushion vehicle the damage to the bottom of the bridge deck cross-connecting the hulls or side walls need only be assumed if that structure is submerged with the craft in the undamaged displacement mode. The width of damage in such a case need not be greater than the separation of the hulls or side walls;

  • (c) the depth of penetration into the craft should be:

    0.02B or 0.5 metres, whichever is less.

Parent topic: Chapter 2 - Buoyancy, Stability and Subdivision
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