Abstract: A watersport board fin has a rigid body element with a leading edge and trailing edge, and a rigid ridge integral with rigid body and extending outwardly from the leading and trailing edges. The ridge has a number of through extending holes formed in it outwardly of the rigid body element, and has an average thickness of about 16-25% (e.g. 18-22%) of the average thickness of the body element, preferably between about 0.1-0.14 cm (e.g. about 0.12 cm). The ridge is substantially completely covered by a flexible material soft enough to minimize injury to a person impacted by it, and flexible enough to be deflected during movement through the water to provide a rudder action. Preferably the flexible material extends along substantially the entire extent of the rigid body element, including the base of the body element, thereby enhancing the safety and rudder performance of the fin. The fin is connected to the bottom surface of a sport board, such as a surfboard, wake board, sail board, water ski, body board, etc.