The boats’ market is in a constant mutation. The proof is the development of the world market for boatbuilders. These last years, the tendency was to own a cruising boat, catamaran type, 45 to 50 feet, to spend 15 days holidays with family or friends. Some years later, the conclusion of the owners is clear : the maintenance and related costs of a boat (harbor, insurance, crane or tender lift ...) are quite high especially if we put these costs in relation with the time spent on board.