2 Criteria for residual stability after damage
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Statutory Documents - IMO Publications and Documents - International Codes - HSC 2000 Code - International Code of Safety for High-Speed Craft, 2000 – Resolution MSC.97(73) - Annex 8 - Stability of monohull craft - 2 Criteria for residual stability after damage

2 Criteria for residual stability after damage

  2.1 The stability required in the final condition after damage, and after equalization where provided, shall be determined as specified in 2.1.1 to 2.1.4.

  2.1.1 The positive residual righting lever curve shall have a minimum range of 15° beyond the angle of equilibrium. This range may be reduced to a minimum of 10°, in the case where the area under the righting lever curve is that specified in 2.1.2, increased by the ratio:

where the range is expressed in degrees. The range shall be taken as the difference between the equilibrium heel angle and the heel angle at which the residual righting lever subsequently becomes negative or the angle at which progressive flooding occurs, whichever is less.

  2.1.2 The area under the righting lever curve shall be at least 0.015 , measured from the angle of equilibrium to the lesser of:

  • .1 the angle at which progressive flooding occurs; and

  • .2 27° measured from the upright.

  2.1.3 A residual righting lever shall be obtained within the range of positive stability, taking into account the greatest of the following heeling moments:

  • .1 the crowding of all passengers towards one side;

  • .2 the launching of all fully loaded davit-launched survival craft on one side; and

  • .3 due to wind pressure,

as calculated by the formula:

However, in no case, this righting lever shall be less than 0.1 m.

  2.1.4 For the purpose of calculating the heeling moments referred to in 2.1.3, the following assumptions shall be made:

  • .1 Moments due to crowding of passengers. This should be calculated in accordance with 2.10 of the Code.

  • .2 Moments due to launching of all fully loaded davit-launched survival craft on one side:

    • .2.1 all lifeboats and rescue boats fitted on the side to which the ship has heeled after having sustained damage shall be assumed to be swung out fully loaded and ready for lowering;

    • .2.2 for lifeboats which are arranged to be launched fully loaded from the stowed position, the maximum heeling moment during launching shall be taken;

    • .2.3 a fully loaded davit-launched liferaft attached to each davit on the side to which the ship has heeled after having sustained damage shall be assumed to be swung out ready for lowering;

    • .2.4 persons not in the life-saving appliances which are swung out shall not provide either additional heeling or righting moment; and

    • .2.5 life-saving appliances on the side of the ship opposite to the side to which the ship has heeled shall be assumed to be in a stowed position.

  • .3 Moments due to wind pressure:

    • .3.1 the wind pressure shall be taken as (120 {V W/ 26}2) (N/m2), where V W = wind speed (m/s), corresponding to the worst intended condition;

    • .3.2 the area applicable shall be the projected lateral area of the ship above the waterline corresponding to the intact condition; and

    • .3.3 the moment arm shall be the vertical distance from a point at one half of the mean draught corresponding to the intact condition to the centre of gravity of the lateral area.

  2.2 In intermediate stages of flooding, the maximum righting lever shall be at least 0.05m and the range of positive righting levers shall be at least 7°. In all cases, only one breach in the hull and only one free surface need be assumed.

Parent topic: Annex 8 - Stability of monohull craft
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