PURPOSE: To prevent the invasion of water, by integrally providing a cockpit on a deck and making the deck as a main-strength member and coupling both the side parts of the decks to each other with a frame so that the cockpit is interposed between the side parts and by attaching a rigger to the deck.

CONSTITUTION: A cockpit 3 is integrally provided on a deck 1. The deck 1 is made as a main-strength member. Both the side parts of the deck 1 are coupled to each other by pipe frame 8 so that the cockpit 3 is interposed between the side parts of the deck. A rigger 6 can be attached to the deck 1. Since the attached position of the rigger 6 is high, it is hard for water to collide against the rigger 6 in sailing to exert resistance to the sailing and invade.