SAIL OPTIMIZATION FOR MAXIMAL SPEED

A variety of approaches to sail optimisation are reviewed. A mathemati cal model is described which allows the optimisation of the spanwise l ift distribution of a high speed craft with a criterion of maximal off wind speed. The model uses a numerical lifting line approach to predic t the aerodynamic forces and moments allied to an empirical model of t he hydrodynamic forces. A further model is presented which yields the optimal sailplan for a yacht based on a criterion of maximal speed mad e good to windward; this may be calculated either for a single windspe ed, or in an averaged sense for a selection of different windspeeds. T he vortex lattice method is used to predict aerodynamic forces and mom ents, whilst the hydrodynamic forces and moments are estimated using a performance prediction approach based on data from the Delft systemat ic yacht hull series. Three variations in rig type are considered: a b asic sloop rig, a sloop rig with a roached mainsail, and a ketch rig. In both models the optimisation is carried out using a genetic algorit hm. Typical results are presented, and scope for future work is discus sed.