Optimisation of wave-piercing trimaran outrigger layout with comprehensive consideration of resistance and seakeeping

Abstract

The outrigger layout of wave-piercing trimarans has an important effect on its hydrodynamic performance. This paper proposes an optimisation method considering resistance and seakeeping performance to form an excellent ship type that can perform tasks well in waves. The wave resistance, roll, pitch, and heave motion responses of the hull when sailing in regular head waves and oblique waves are selected as optimisation objectives. On the basis of the uniform design, sample points are generated for computational fluid dynamics numerical calculation. Support vector regression optimised by genetic algorithm is used to build an approximate model and to reduce optimisation time. On the basis of nondominated sorting genetic algorithm-II, a Pareto-optimal front is obtained. The outrigger layout optimisation of trimaran shuttle vessel is taken as an example to verify the feasibility and efficiency of the proposed optimisation method. Results indicate that the multiobjective optimisation considering sailing in head waves and oblique waves can obtain a wave-piercing trimaran outrigger layout with better resistance and seakeeping performance. The proposed optimisation method may provide solutions for the optimal design of trimaran outrigger layout.