The effect of hull cross section on the theoretical wave resistance of a fast ship in shallow water

Existing linearised wave theory for the resistance of a ship in both deep and shallow water has been used to calculate the effect of shallow water on a fast ship moving at high sub-critical and also at super-critical speeds. In earlier work the real hull was represented by a simplified hull shape which was symmetrical fore and aft with parabolic water planes and rectangular cross-sections. The present work improves the representation of the hull by replacing the rectangular cross-section with a wedge shape for a planing hull and a parabolic cross-section for a round bilge displacement hull.

A comparison of the calculated results with the available data shows that the change in hull cross-section only made a noticeable difference in the region of the sub-critical resistance peak and tended to slightly lessen the agreement between the theory and the existing experimental data.