Energy saving and dynamic stability of planning hull due to hydrodynamic control of trim angles

摘要

To find the most suitable trim angle for a planning hull, as a high-speed marine craft, is not an easy task. The right trim angle yields the best performance of a planning hull. It is the main task of this work to develop and provide proposed design contours for the best planning hull trim angles. These trim angles should yield minimum total drag and keep the hull off dynamic-instability regime (porpoising), at different speed ranges. This has been accomplished through hydrodynamic investigation of planning hull performance at different trim angles and speed ranges. In the present work, hydrodynamic equilibrium of planning hull has been considered. In addition, new hydro-dynamic applications of transom flap, longitudinal shifting of weights, and proposed wind spoiler have been introduced as trim controlling devices. These applied devices improve and optimize the control of planning hull trim angles at different speeds, aiming to achieve best possible planning hull performance. To perform an optimization process and develop design contours for the best operating trim, three phases of computer program, have been specially designed. Applications of the present analysis have been performed on specific planning hull geometry. Useful and encouraging, results for the best trim angles operating regimes have been determined for different hull designs at different ranges of speed.