Hydrodynamic swim fin

Abstract

An improved hydrodynamic swim fin utilizes a wing and a tail that are overlapped normally to provide a two-stage propulsion system. Ribs support the wing and tail and define flow channels. These ribs are parallel to each other and to the longitudinal axis of the fin whereby the effective area through which flow proceeds is uniform throughout the length of the fin. No parts of the ribs form barriers to the leading edges of the side wing segments whereby laminar flow is achieved. The fin part is maintained essentially rigid; however, the fin part is allowed limited angular movement about a defined transverse axis to achieve proper attack angle. Since the fin part is rigid, it maintains that attack angle throughout the length of the fin part. Trailing ends of the wing are individually flexible to produce greater opening for two-stage propulsion during the power downstroke, and to produce substantial closure for one-stage propulsion during the upstroke. Leading ends of the side wing segments are individually flexible to permit a truer hdyrofoil shape in response to angular movement of the fin part about the transverse axis. Deflectors prevent obstructions such as kelp from reaching the lateral wing segment flow channels. Strakes positioned parallel to the ribs along the leading ends of the wing segments and the tail also promote laminar flow through and along the fin part.