Abstract: The present invention pertains to an apparatus to improve the efficiency and performance of an aerodynamic lift structure for use on sailing devices. A two-sided, spaced apart sail structure is provided with resiliently deformable struts for each side, attached at one end to a beam, fixed to the mast of the sailing device, the mast being rotatable about its vertical axis in either direction relative to vertical planes along the longitudinal axes of the sailing device and the boom in a manner whereby a cam action is produced by the beam to deform or bend the struts in a manner so as to vary the camber of the wing sail, the amount of camber of one side of the wing sail being greater than the concave curvature of the opposed side thus producing an airfoil configuration.