Resistance and Seakeeping Optimization of a Fast Multihull Passenger Ferry

Semi-Small Waterplane Area Twin Hull (Semi-SWATH) ferry is optimized by an automatic procedure with respect to seakeeping and resistance at different speeds. The numeric procedure is based on a fully parametric model of the unconventional hull form, a 3D linear Rankine sources panel method for the steady wave resistance and the seakeeping problem, and a multiobjective global convergence genetic algorithm. Both global and local shape variations are allowed in order to explore highly unconventional hull shapes. Interesting results are obtained from the optimization considering resistance at the two very different speeds and including or not the seakeeping merit functions. Considerable reductions of drag and vertical acceleration can be obtained from the optimization procedure on the order of 15% on drag at high speeds and 30% on vertical acceleration in most exposed passenger areas.