The Levenberg-Marquardt Method (LMM) and the commercial code SHIPFLOW are utilized in the present inverse hull design problem for minimizing wash wave of the catamaran. The hull form of the catamaran is described by the B-spline surface method so that the shape of the hull can be completely specified using only a small number of parameters (i.e. control points). The technique of parameter estimation for the inverse design problem is thus chosen. In the present studies, the inverse hull design method can not only be applied to estimate the hull form based on the known wave data of the target ship but also be applied to estimate the unknown hull form based on the reduced wave height. The optimal hull forms of minimizing wash wave for a typical catamaran in deep water at service speed and at the critical speed of shallow water are estimated, respectively. Moreover, the hull form performing well under both conditions can also be obtained by combining the optimal hull forms for deep water and shallow water. Numerical results show that the hull form designed by inverse hull design method can minimize the wash wave significantly in comparison with the original design configuration.
RECENTLY following the development of modern high-speed ferry, it had attracted worldwide attention for the wash wave problem of these fast vessels. According to Wood (2000), the high-speed ferries generate two groups of wash waves with periods of 3 to 5 seconds and 8 to 10 seconds. The long period waves are generally not easily visible from the ship due to their low amplitude. These long waves contain more energy than short waves and they also travel faster than short wave, so they will reach the beach or small boat in open sea earlier than the short period visible wave.