Concept development and design ofretractable hydrofoil systems

Sammanfattning: The Swedish Sea Rescue Society (SSRS) is a non-profit organisation which performs themajority of rescue missions on Swedish waters. SSRS together with many other companies arecurrently under development of a novel boat design which is battery powered. This leads to aspecific challenge of shorter available reach compared to the traditional diesel engine poweredboats. The solutions is to make use of hydrofoils which enables the potential for the hull to belifted above sea level and reduce drag resistance by up to 80% The purpose of the project was to through a broad background study, develop systems that allowretraction and extension of the hydrofoil from the hull of the boat. After generating 10 concepts,these were evaluated by performing an elimination- and decision matrix. Two concepts werechosen to be further developed. The two concepts were in many aspects similar in regards tocomponents and the outline of them except one was actuated by a multi-stage hydraulic cylinderand the other by a servo motor and roller screw. Analytical calculations, choice- anddimensioning of components and FE-analysis in NX Nastran were done in the furtherdevelopment-stage. It was found that both solutions were viable options to integrate as hydrofoil extension andretraction mechanisms on an electric boat. After completion and interpretation of the results itwas concluded that an electromechanical solution would be prefered to use as the underlyingtechnology for the lifting mechanism.