On Wave-making Hydrodynamic Forces and Wave Pattern of a Sailing Yacht

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making hydrodynamic forces for the application to ship design. A sailing yacht is chosen for an example of practical ship, which has been designed by Nippon Challenge America's Cup Committee to aim at the next race in 1991.The paper deals with the numerical calculation of potential flow around the sailing yacht with forward velocity and a drift angle by the new slender ship theory. Kelvin sources distributed over the hull surface are determined by solving the small matrix at each transverse section so as to satigfy the approximate hull boundary condition due to the assumption of slender body, and the calculation begins at the bow end and marches step by step to the stern end. It is seen that such a numerical procedure is efficient not only for reducing computer time but also for the accuracy of computation. Here hydrodynamic forces acting on the hull without or with a keel, wave resistance, lateral force and yaw moment are obtained by integrating pressure over the hull and the keel surface. Wave patterns in the neighborhood of the hull are calculated from the formula of wave elevation on the free surface. Thereafter those calculated results are compared with measured ones. It can be seen by the present method whether the propulsive performance of a yacht is good or not.