Using the Wave Propulsors in a Small-Waterplane-Area-Twin-Hull Boat

The efficiency of two types of wave propulsors (WPs) (a swinging spring-loaded wing WP
and a direct-flow WP) is experimentally studied on a model of a small-waterplane-area-twin-hull
(SWATH) boat. The NACA0015 airfoil was used as an operating element of both the swinging and the
direct-flow WPs. In the case of a direct-flow WP, the flat airfoil was rigidly fixed relative to the boat
hull with a chord inclination of 30. The operating efficiency of the wave propulsors is studied for
waves of various lengths depending on the draft of the SWATH boat hulls, and in the case of a swinging
spring-loaded wing WP, also on the submergence depth of the propulsor. Using the results of towing
tests, the thrust force of a direct-flow WP is estimated under various operating conditions. It is found
that with increase in the submergence depth of the boat hulls, the efficiency of the direct-flow WP
increases, while the efficiency of the swinging WP decreases, however, it largely retains its operability,
provided that the WP operating element remains at the optimal depth close to the water surface.