Inverse design of ship hull forms for seakeeping

This paper describes a computational procedure to design seakeeping optimized ship hull forms using optimization techniques. The hull form optimization procedure contains four basic elements; a procedure for representing alternative hull form designs, a procedure for predicting seakeeping performance of a given design, a nonlinear direct search procedure, and a user interface to provide objectives and constraints of the problem. The seakeeping performance of the ship in a specified sea area is expressed as a function of selected hull form parameters. A nonlinear optimization problem is then formulated and solved by using nonlinear direct search techniques. Several alternative objective functions ranging from single response amplitude operators to complex operability indices can be used. The constraints may include both geometric and performance requirements. The methodology is applied for a typical motoryacht form which represents the modern hull form characteristics. First a single-objective optimization problem is formulated and solved to derive optimized hull forms with significantly reduced seakeeping responses. Then a multi-objective optimization problem which takes into account different aspects of seakeeping performance is formulated. The results indicate that complex and conflicting requirements exist between seakeeping characteristics and hull form properties. Despite this complexity, it is shown that, provided that the designer can specify the objectives and constraints of the problem an optimized hull form with improved seakeeping performance can easily be obtained.