Propulsion apparatus for an aquatic vessel comprises an aerodynamic body which extends along a longitudinal axis between first and second ends and in a transverse direction between a leading edge and trailing edge. The aerodynamic body has one or more external wind-receiving surfaces which extend between the leading edge and the trailing edge, thereby defining an aerodynamic profile of the aerodynamic body in cross-section substantially perpendicular to the longitudinal axis. The propulsion apparatus further comprises at least one air vent and at least one air flow generator configured to expel air through the at least one air vent. The at least one air vent and/or the at least one air flow generator are configured to direct expelled air across at least a portion of the one or more or more external wind-receiving surfaces.