This paper presents the application of state-of-the-art Computational Fluid Dynamics (CFD) simulations to sailing and motor yachts. It aims to demonstrate that simulations are a good alternative to tank testing for the super and mega yacht industry. The simulations are based on experience gathered over the last few years designing high performance racing boats, especially in America's Cup and Volvo Ocean Race campaigns, the Formula One of the seas. CFD is one of the new technologies that can, as was done in the auto industry, be successfully transferred from the racing environment to general industry. In particular, the super and mega yacht industry can now benefit from the recent advances in CFD. Cape Horn Engineering is a company that specializes in hydrodynamic and aerodynamic CFD for the marine industry. This paper presents a general yacht design philosophy based on simulations and its application to a typical power boat
and a large sailing yacht.