1.2 Transitional and foil-borne modes
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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 6 - Stability of hydrofoil craft - 1 Surface-piercing hydrofoils - 1.2 Transitional and foil-borne modes

1.2 Transitional and foil-borne modes

  1.2.1 The stability shall satisfy the provisions of 2.4 and 2.5 of this Code.

  1.2.2.1 The stability in the transitional and foil-borne modes shall be checked for all cases of loading for the intended service of the craft.

  1.2.2.2 The stability in the transitional and foil-borne modes may be determined either by calculation or on the basis of data obtained from model experiments and shall be verified by full-scale tests by imposition of a series of known heeling moments by off-centre ballast weights, and recording the heeling angles produced by these moments. When taken in the hull-borne, take-off, steady foil-borne and settling to hull-borne modes, these results will provide an indication of the values of the stability in the various situations of the craft during the transitional condition.

  1.2.2.3 The angle of heel in the foil-borne mode caused by the concentration of passengers at one side shall not exceed 8°. During the transitional mode the angle of heel due to the concentration of passengers on one side shall not exceed 12°. The concentration of passengers shall be determined by the Administration, having regard to the guidance given at annex 7 to this Code.

  1.2.3 One of the possible methods of assessing foil-borne metacentric height (GM) in the design stage for a particular foil configuration is given in figure 3.

Figure 3 Section through front foil; Section through aft foil

 

where:
n B = percentage of hydrofoil borne by front foil
n H = percentage of hydrofoil load borne by aft foil
L B = clearance width of front foil
L H = clearance width of aft foil
a = clearance between bottom of keel and water
g = height of centre of gravity above bottom of keel
l B = angle at which aft foil is inclined to horizontal
l H = angle at which aft foil is inclined to horizontal
S = height of centre of gravity above water
Parent topic: 1 Surface-piercing hydrofoils
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