The effect of heel angle and free-surface proximity on the performance and strut wake of a moth sailing dinghy rudder T-foil

Abstract

The use of hydrofoils for sailing yachts is becoming more prolific. However its use in mainstream sailing classes has only become standard for the Moth dinghy class. The Moth class uses a twin T-Foil design, one on the centreboard for primary support and one on the rudder for additional support and control. The rudder T-Foil forms the basis of an experimental study carried out at the Australian Maritime College towing tank facility described here. Lift and drag data is presented for upright and heeled configurations considered indicative of windward sailing conditions. Force variation with respect to angle of incidence, depth of submergence and onset flow speed is presented using elliptical lift distribution parameters for easy design use. In addition deflection of the strut run-up was attempted to produce additional lift. Finally, a windward sailing condition prone to ventilation has been identified.