Advanced and future hydrodynamic optimisation tools in sail yacht design

Since the beginning of high level sailing events, like the America’s Cup and Volvo Ocean Race, designers have used a varied and increasing set of techniques on the experimental and later on the numerical field in design sailing yachts. This paper will give the latest developments for the different fields at MARIN.
In the field of CFD calculations, the program RAPID has been extended with a sailing yacht module, which solves the exact, fully non-linear potential flow problem by an iterative procedure. This paper highlights the comparison of CFD results with some experimental results, for a small range of different sailing yacht designs.
A small introduction will be given about the new underwater, three-component particle image velocimetry system (3c-PIV or stereoPIV). With aid of such a system it is possible to measure and visualise the flow around appendages such as keel, winglets bulb and rudder.
Even if investigated in many occasions in the past, mainly through calculations, performances in dynamic conditions are not yet part of the standard design spiral. Seakeeping and manoeuvring aspects require more variables than steady conditions and require more complex numerical and experimental tools, which probably explain partly their nearly total absence into the design process. At a time where optimisation has reduced drastically the scatter into hull performance, seakeeping and manoeuvring aspects can be seen as new fields open for potential increase in performance and create the difference with other designs.
The present paper discusses the current state at MARIN for each of those fields, their applicability and limitations. The demand for high accuracy tools is increasing, and techniques to further improve the sailing yacht design are becoming available.