ABSTRACT
The roll motion for fishing vessels in beam seas with zero speed deserves to be a significant criterion for ship safety evaluation. High-speed fishing vessels are prone to the surf-riding and broaching in adverse quartering and following seas with potential safety implications. The possibility of improving roll motion responses for the ITTC-A2 high-speed fishing vessel is investigated delicately through ship hull form optimization. During the process, the ship hull surfaces are reconstructed accordingly using the Radial Basis Function (RBF) interpolation technique through adjustments of a limited number of RBF control points. The statistical roll motion responses at irregular waves are numerically predicted through the general hydrodynamic software based on 3-D potential theory. The surf-riding characteristics in following seas are studied in detail through the IMO recommended level 2 vulnerability criteria for surf-riding/broaching. In addition, the calm water resistance along with the optimization process is monitored by the corrected Holtrop Method. The optimum hull form is obtained through the application of NSGA-II genetic algorithm, which is effective and robust for multi-objective optimization problems. The results indicate that the proposed ship hull form optimization method is an efficient approach for improving roll motion responses with only limited impacts on surf-riding and calm water resistance performances for high-speed fishing vessels and deserves to be generalized into a conventional method for improving general ship performances at initial design stage.
