Development of a Velocity Prediction Program for a High Performance Eco Sustainable SKIFF Sailing Yacht

In nowadays high-performance sailing yacht design, a performance prediction tool capable of identifying the speed of the boat in numerous sailing conditions as a function of several design parameters is considered a crucial success factor. In the present work, a VPP is developed using validated results from CFD simulations for the hydrodynamic forces and an indirect approach to simulate the aerodynamic forces generated by the sail plan. Detailed performance results, together with a parametric study to highlight the influence of a few final design parameters on the boat speed, are presented for an R3 class SKIFF sailing yacht. The program takes as inputs the geometry and design of the boat, the sailor's mass and a range of true wind speed conditions and returns the boat speed, the displacement of the crew in order to maintain a zero roll angle, the leeway angle, the optimal equivalent sail lift coefficient as well as all the major forces acting in their relative center of pressure. The equilibrium equations are solved for each cycle on true wind angles and true wind speed, using a gradient based method that finds the minimum of a constrained nonlinear multivariable function. The solution found by the iterative method is the one that maximizes the velocity made good on course (VMC) of the boat under the specified conditions and constraints, for each true wind angle possible and low to medium wind speeds, accordingly to the average wind conditions of the regatta's location in which the boat will have to perform.