Recent advances in high-speed computing have benefited the field of computational fluid dynamics. Ship designers can now analyze by computer complex water- and air-flow behavior, previously poorly understood through expensive and time-consuming testing with scaled ship models. These improved computational fluid dynamics techniques are revolutionizing the ship design process and enabling better designs to be produced more quickly. This article provides an overview of the use of computational fluid dynamics in ship design; and then its use, along with theory and experiment, in design of sailing vessels for racing.