To form the inner surface of a storage part into the smooth surface so as to prevent stored articles from getting dirty without taking time for finishing work or the like by forming the bottom wall of a casing of a part of a deck member, and fitting separate member from the deck member to at least part of the upper wall and peripheral wall of the casing.

A bottom wall 47 of a bow storage part is formed at the front end part of a deck 21 to be the bottom wall of a cockpit 10, and a lower peripheral wall 46 of the bow storage part is formed at the lower part front end part of a peripheral wall 22 of the cockpit 10. A storage part member 4 is then fixed to the upper side of the lower peripheral wall 46 by sealing to form the bow storage part, and these bottom wall 47, lower peripheral wall 46 and storage member 4 constitute a casing for the storage part. In a deck member 2, the upper face of the deck 21 to be the outer surface, and the inner surface of the peripheral wall 22 are formed in the smooth surface as the molded face, and the peripheral wall 22 forms the inner surface of a bulwark. The rough inner surface of a hull member 1 is therefore covered with the deck member 2, so that the cockpit 10 has the smooth surface inside.