Study on Optimum Design Methods for Various Types of Ships

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Some optimizing methods are presented in order to design hull forms of various types of ships. The obtained results are the followings. 1. Minimum resistance ship form with bow and stern bulbs is developed by using a non-linear optimization technique, SUMT method.(1) A ship form with bow and stern bulbs is more favorable in the aspect of wave resistance than the one with only bulbous bow.(2) However, it is made clear by a model experiment that a large stern bulb causes flow separation and increase of viscous resistance. The estimation of separation zone is developed.2. Optimum hull forms for ship motion in wave are obtained by using the so-called GRG method.(1) The hull form minimizing the ship motion has smooth V-shaped sections in bow and stern part.(2) However, the hull form minimizing the exciting force undulates greatly, while the force, Froude-Krylov force, is really minimum.3. A preliminary theory to optimize the plane form of a WIG(Wing in ground-effects) is presented based on conservation law of fluid.(1) Almost no effects of end plates at the leading edges of semi-elliptic plan form WIG are observed for suppressing out-flowing there, but increasing normal force.(2) Fitting of about 30% length of end plates to the overall from the trailing edge is optimum for increasing normal force.