添付資料4

Annex A

(normative)

Simplified calculation method for motor craft scantling

This simplified method may apply only to the calculation for the design pressure and the plating of motor craft with less than 12 m length of hull on the following points, instead of using clause 5, 6, and 7 on this standard.

　

A.　Design pressure

　

A.1　Motor craft bottom design pressure

　

　

η_cg is the dynamic load factor = average 1/100 of the highest accelerations at LCG

? is the displacement mass on design waterline, in kilograms. The value of displacement ? for the heaviest and lightest service conditions shall be considered with the corresponding speed.

L_wl is the length on the design waterline, for the long condition under consideration, the craft being at rest in metres.

B_c is the maximum chine beam, in metres.

B_c　shall be measured at the LCG position, if known, or at 0.4 L_wl forward or transom if LCG is not known, by drawing a tangent of 50 degrees from the horizontal to the hull contour (see Figure 2).

V is the maximum speed in calm water, in knots, to be formally declared by the manufacturer, related to the appropriate displacement ?. The speed of the craft is assumed to be appropriate to the prevailing sea state.

K_ar is the design area factor for ratio for A_d/A_r, as given in figure 5.

　

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