2.1 General
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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) - Chapter 2 - Buoyancy, stability and subdivision - PART A — GENERAL - 2.1 General

2.1 General

  2.1.1 A craft shall be provided with:

  • .1 stability characteristics and stabilization systems adequate for safety when the craft is operated in the non-displacement mode and during the transitional mode;

  • .2 buoyancy and stability characteristics adequate for safety where the craft is operated in the displacement mode, both in the intact condition and the damaged condition; and

  • .3 stability characteristics in the non-displacement and transitional modes adequate to transfer the craft safely to displacement mode in case of any system malfunction.

  2.1.2 Account shall be taken of the effect of icing in the stability calculations. An example of established practice for ice accretion allowances is given in annex 5 for the guidance of the Administration.

  2.1.3 For the purpose of this and other chapters, unless expressly defined otherwise, the following definitions apply:

  • .1 Downflooding point means any opening, irrespective of size, that would permit passage of water through a water/weathertight structure (e.g., opening windows), but excludes any opening kept closed to an appropriate standard of water/weathertightness at all times other than when required for access or for operation of portable submersible bilge pumps in an emergency (e.g., non-opening windows of similar strength and weathertight integrity to the structure in which they are installed).

  • .2 Elsewhere, when applied to sill and coaming heights in 2.2.7 and 2.2.8 is taken as applying to all weathertight and watertight closures located on or below the datum.

  • .3 Fully submerged foil means a foil having no lift components piercing the surface of the water in the foil-borne mode.

  • .4 Monohull craft means any craft which is not a multihull craft.

  • .5 Multihull craft means a craft which in any normally achievable operating trim or heel angle has a rigid hull structure which penetrates the surface of the sea over more than one discrete area.

  • .6 Permeability of a space means the percentage of the volume of that space which can be occupied by water.

  • .7 Skirt means a downwardly extending, flexible structure used to contain or divide an air cushion.

  2.1.4 Other means of demonstrating compliance with the requirements of any part of this chapter may be accepted, provided that the method chosen can be shown to provide an equivalent level of safety. Such methods may include:

  • .1 mathematical simulation of dynamic behaviour;

  • .2 scale model testing; and

  • .3 full-scale trials.

  2.1.5 The adequacy of mathematical simulations must first be demonstrated by correlation with full-scale or model tests for the appropriate type of craft. It may be appropriate to use mathematical simulations to help to identify the more critical scenarios for subsequent physical testing.footnote

  2.1.6 Model or full-scale tests and/or calculations (as appropriate) shall also include consideration of the following known stability hazards to which high-speed craft are known to be liable, according to craft type:

  • .1 directional instability, which is often coupled to roll and pitch instabilities;

  • .2 broaching and bow diving in following seas at speeds near to wave speed, applicable to most types;

  • .3 bow diving of planing monohulls and catamarans due to dynamic loss of longitudinal stability in relatively calm seas;

  • .4 reduction in transverse stability with increasing speed of monohulls;

  • .5 porpoising of planing monohulls, being coupled pitch and heave oscillations, which can become violent;

  • .6 chine tripping, being a phenomenon of planing monohulls occurring when the immersion of a chine generates a strong capsizing moment;

  • .7 plough-in of air-cushion vehicles, either longitudinal or transverse, as a result of bow or side skirt tuck-under or sudden collapse of skirt geometry, which, in extreme cases, can result in capsize;

  • .8 pitch instability of SWATH (small waterplane area twin hull) craft due to the hydrodynamic moment developed as a result of the water flow over the submerged lower hulls;

  • .9 reduction in effective metacentric height (roll stiffness) of surface effect ship (SES) in high speed turns compared to that on a straight course, which can result in sudden increases in heel angle and/or coupled roll and pitch oscillations; and

  • .10 resonant rolling of SES in beam seas, which, in extreme cases, can result in capsize.

  2.1.7 Suitable calculations shall be carried out and/or tests conducted to demonstrate that, when operating within approved operational limitations, the craft will, after a disturbance causing roll, pitch, heave or heel due to turning or any combination thereof, return to the original attitude. Where calculations are employed, it shall first be shown that they correctly represent dynamic behaviour within the operational limitations of the craft.

Parent topic: PART A — GENERAL
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