2 Criteria for residual stability after damage
Clasification Society 2024 - Version 9.40
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 7 - Stability of multihull craft - 2 Criteria for residual stability after damage

2 Criteria for residual stability after damage

  2.1 The method of application of criteria to the residual stability curve is similar to that for intact stability except that the craft in the final condition after damage shall be considered to have an adequate standard of residual stability provided:

  • .1 the required area A 2 shall be not less than 0.028 (figure 2 refers); and

  • .2 there is no requirement regarding the angle at which the maximum GZ value shall occur.

Figure 2 Damage Stability

  Abbreviations used in figures 1 and 2:

HL 2 = Heeling lever due to wind + gusting
HLT = Heeling lever due to wind + gusting + (passenger crowding or turning)
HL 3 = Heeling lever due to wind
HL 4 = Heeling lever due to wind + passenger crowding
θ m = Angle of maximum GZ
θ d = Angle of downflooding
θ r = Angle of roll
θ e = Angle of equilibrium, assuming no wind, passenger crowding or turning effects
θ h = Angle of heel due to heeling lever HL 2, HTL, HL 3 or HL 4
  • A 1 > Area required by 1.1
  • A 2 > 0.028

  2.2 The wind heeling lever for application on the residual stability curve shall be assumed constant at all angles of inclination and shall be calculated as follows:

where:
Pd = 120 (V W/ 26)2 (N/m2)
VW = wind speed corresponding to the worst intended conditions (m/s)
A = projected lateral area of the portion of the ship above the lightest service waterline (m2)
Z = vertical distance from the centre of A to a point one half of the lightest service draught (m)
Δ = displacement (t).

  2.3 The same values of roll angle shall be used as for the intact stability, as determined in 1.5 of this annex.

  2.4 The downflooding point is important and is regarded as terminating the residual stability curve. The area A 2 shall therefore be truncated at the downflooding angle.

  2.5 The stability of the craft in the final condition after damage shall be examined and shown to satisfy the criteria, when damaged as stipulated in 2.6 of this Code.

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

Parent topic: Annex 7 - Stability of multihull craft
Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.