Having good resistance and seakeeping performances, a trimaran usually consists of a main hull and two side hulls, which has already been one of the most noticed high-performance vessels. In order to optimize the total drag of the trimaran, hydrodynamic evaluation is an unavoidable and vital part. Using technology of Computational Fluid Dynamics, the evaluation of ship's hydrodynamic performances is mainly based on the potential-flow or viscous-flow theory. In order to reduce its total drag at Froude number 0.3, the hull form optimization solver OPTShip-SJTU is used to deform the spacings of the side hulls, which are regarded as optimization design variables. After evaluations of new sample hulls created by Optimal Latin Hypercube Sampling method, Kriging surrogate models are then constructed to save the computational cost. Finally, using Genetic Algorithm, the optimal hulls are obtained by two evaluation methods, and the optimal trimarans are further compared and analyzed to see the differences of two evaluation methods and its effect on the obtained optimal hulls.
Apart from catamaran, trimaran has become one of the most growing high-performance ships in these days due to their good performances including stability, resistance and seakeeping. In the early stage of the trimaran design, the resistance performance should be considered at first in order to save energy and reduce pollution.
A trimaran usually consists of a main hull and two same side hulls. The total drag of trimaran is mainly determined by the hull shape and spacings of the main and side hulls. Since the spacings including lateral spacing and longitudinal spacing of the side hulls relative to the main hull have a great impact on the wave-making interference between the demihulls, in order to optimize the total drag of the trimaran at the very first phase of the optimization design, the two spacings should be considered as the design variables.