Abstract: A thick, elliptical-planform fin for use on a water sport board such as a surfboard. One set of attributes of the fins according to the present invention is the use of a substantially thick cross-section which, at its maximum thickness, overhangs the receiver slot, typically a 12 to 15 percent thickness ratio, with a maximum thickness at 30 percent of chord length, a blunter leading edge, and a short elliptical planform of constant relative dimension cross-section along its length.