A WIND-TUNNEL INVESTIGATION OF YACHT HYDRODYNAMIC SIDE FORCE AND DRAG

Measurements of side force and drag on models of various yacht hull/ke el combinations in a wind tunnel are presented. The accuracy of the re sulting side force measurements was verified by comparing results for two of the standard configurations with towing tank data from geometri cally identical models at the same Reynolds number. The agreement betw een the results was excellent. Measurements from the models were then compared with the predictions of five different methods for a range of keel to canoe body draft ratios from 2.27 to 5.56. It was found that there was considerable variation in the predictions of the various met hods, but that the wind tunnel results fell at the center of the range of predicted values. Effective aspect ratios were estimated from indu ced drag measurements and were found to be in excess of twice the geom etric aspect ratio of the keels, reducing as heel increased to 30 deg.