Development of a high speed planing trimaran with hydrofoil support
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007.
The successful use of hydrofoil systems on catamarans, such as the Hysucat, led to the development of a similar foil system for a high speed trimaran. Firstly a mathematical model was developed to calculate the equilibrium planing conditions of a planing trimaran. This was then used in the hydrodynamic design of a fully planing trimaran with a design speed of 65 kn. The mathematical model was then modified to include the effects of added hydrofoils. This model was then used to design a hydrofoil support system for the planing trimaran. Towing tank tests were then performed on a scale model of the boat, with and without the supporting hydrofoil system. This was done to verify the theoretical design and to gather resistance data, which could then be compared to other boats. The results showed a notable improvement in efficiency of the boat with the addition of foils. The conclusion was made that with the addition of a well-designed foil system, hull efficiencies similar to that expected for the Hysucat, can be attained when the foil system is added to the trimaran. As this work was focused mainly on the high-speed performance of the boat, it is not certain how the boat will perform through the speed-range. It is therefore recommended that further testing be done, to determine the performance of the boat at lower speeds.