Study on motions of a sailing boat

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Research works on sailing boats have a long history, but they are only empirical based on experiences of good sailors and designers. One of the exception is research for America's cup. Even that research is just on steady sailing performance. This research is on unsteady performance such as tacking and pitching, which are crucial for yacht races and ocean cruise. The following results are obtained.1.We developed the tacking simulator based on a mathematical model of four degrees of freedom of motion considering hydrodynamic forces acting on the heeled asymmetrical hull.2.We developed the identification method of the main unsteady hydrodynamic force coefficients of the mathematical model utilizing the recorded motion of the boat tested in real sea.3.We developed the measuring system of the boat motion tested in real sea, and measured it in good accuracy.4.The direction of the wind fun of the basin with wave, wind and current was rearranged in order to carry out free running tests of a radio controled sailing boat model. Speed reduction of the boat due to incident waves was measured. The mechanism of the speed reduction was investigated.5.Forced pitching tests of the sail were carried out in the wind tunnel. Added masses, damping coefficients and lift reduction were measured, and compared with newly developed strip theory based on 2-D oscillating wing theory.Furthermore FRP sandwich structures were analyzed by FEM in order to obtain light, rigid and strong hulls. Partial structures were made to confirm the applicability of the theory as well as to obtain practical production know-how.