Abstract: This paper uses the three-dimensional waving plate model and optimummotion theory to analyse lunate-tail swimming propulsion, and so a comparatively systmatic study of the three classes of fish propulsive modes has been carried out. Theoretical results show that lunate-tail, with high-aspect-ratio, spanwise tapering tip and moderate sweepback angle, of many fast-swimming ocean animals, may gain the nearly best propulsive characteristics. Estimation of a porpoise swimming performance gives satisfactory resul...