Abstract
The conventional screw propeller is widely used to propel boats and underwater vehicles. Recently, the use of a bio-inspired oscillating elastic fin has been proposed as an alternative propulsion mechanism. It is thought that the new mechanism will improve efficiency and safety, relative to the screw propeller. The optimum elasticity of the fin is not constant and changes based on swimming speed and task. However, it is very difficult to exchange fins of different stiffness while moving. We have developed a propulsion mechanism using a variable stiffness fin with torsional rectangular elastic plates. In this study, we made a model boat to provide basic data for the development of the boats and autonomous underwater vehicles using the variable stiffness fin. In this paper, we examined the propulsion characteristics of the model boat using two different shapes of the fins: previous rectangle fin and crescent shaped fin.
