Objectives  To study the influence of side-hull layout of trimaran on its motion performance,

  Methods  A new method which is based on Monte Carlo method and potential flow theory is presented to help side-hull layout of trimaran optimize its motion and multi-objective optimization models and calculation techniques are provided. Firstly, we use Monte Carlo method to select the solutions and use AQWA software(potential flow theory) to calculate the motion responses of these solutions. Then by comparing the rolling, pitching and heaving motion responses of these solutions, we select the optimization solution in which these three indicators are all smaller than those of the original ship.

  Results  The results show that in the regular wave, the motion responses of the trimaran are reduced when side-hull is located before the mid-ship of the main-hull. In irregular wave, the roll motion of the trimaran is decreased when side-hull is located before the mid-ship of the main-hull; Also in the regular wave, the roll motion and pitch motion are decreased when we increase the lateral distance between the side-hull and the main-hull.

  Conclusions  To study the influence of side-hull layout on the motion of trimaranon, using Monte Carlo method and potential flow theory can increase calculation efficiency and guarantee high calculation accuracy.