Manufacturing and Preliminary Testing of a Subscale Suspension Boat

Vertical accelerations have been a major problem for high speed boats for a long time. In order to fix that, a suspension boat concept was developed and patented by Professor Joachim L. Grenestedt. A number of small-scale suspension boats have been tested with very good result. A full-scale two-seat manned suspension boat is presently being manufactured at Lehigh. The goal of the present project was to manufacture and test a 1:6 scale model of this boat. This boat has a center fuselage to which four sponsons are mounted vie suspension links, springs and shock absorbers. Suspension boat center hull, or fuselage, was built of carbon fiber prepreg in a CNC machined cavity mold. It is essentially an exact scale model of the full-scale boat. However, the sponsons were much simplified and used only to quickly evaluate the ride and some basic parameters. The boat was equipped with an inboard brushless motor driving a fixed surface piecing propeller via a flex shaft. A rudder mounted in the slipstream behind the propeller was used for directional control. The power and rpm of the motor was logged, as well as GPS speed in later runs. The small-scale boat in general performed very well, although steering was quite poor. Improving steering is under way.