Optimization of an air cushion vehicle bag and finger skirt using genetic algorithms

The air cushion vehicle (ACV) is the advanced marine vehicle that provides not only excellent performance on rough surfaces but also the high speed that other conventional marine vehicles could not achieve. Hence, a large number of ACVs have been utilized for various purposes and missions. At the present the flexible skirt system, the bag and finger skirt, is recognized as the most updated and advanced skirt system. In this paper, the ACVʹs bag and finger skirt system geometry is optimized to modify an undesirable heave response for the better ride quality by using the Genetic Algorithm (GA). The pure heave motion of a two dimensional section of the bag and finger skirt system is investigated using a mathematical model. Two configurations representative of a 37 ton vehicle used by Canadian Coast Guard (CCG) and 150 ton vehicle used by US Navy show a resonance associated with the skirt mass at frequencies at which humans are most sensitive. New skirt geometry obtained by GA considerably ameliorates this effect, and the ride comfort of the optimized ACV can be greatly improved compare to the original configuration within the given constraints such as the required vehicleʹs hard structure dimensions and weight.