A large part of the drag experienced by fast sailing boats originates from the energy radiated at the sea surface by waves. Optimising hull shape in order to minimise wave resistance requires thus a good knowledge of the wave structure created by the ship as well as its evolution with boat heel and boat speed. This knowledge usually originates from numerical simulations or towing experiments. We present here an optical method allowing the determination of the instantaneous 3D water surface shape with a good vertical resolution on large horizontal scales. This method may be useful in towing tank tests and should allow detailed comparisons with computed surface deformation and thus help to validate Velocity Prediction Programs.

This paper presents RANSE computations of steady flows around sailing yachts including the dynamic sinkage and trim, and simulations of unsteady boat motions in incident waves. The steady flow computations efficiently yield the complete resistance curve in one go - from zero to maximum boat speed - instead of computing only for one boat speed at the time. This allows to compare differences in resistance for the entire Fn-range e.g. due to small modifications in the boat’s shape or due to shifting the centre of mass of the boat.  The simulations of boat motions in waves aim to show that the method is robust enough and well suited for simulating the boat’s responses to waves coming from any direction.  With CPU times of a few hours on common personal computers for each characteristic wave, this method promises great potential for the near future.