PURPOSE: To prevent a drain port from being seen from outside and prevent waves from flowing back through the drain port by a method wherein a recess is formed at the lower surface of a auxiliary fender on a side and the drain port of a side wall is opened into the recess at a position close to a bow.

CONSTITUTION: In small-type boat wherein water on the upper surface of a deck is drained to the outside through the drain port 9 opening at the side wall 8, the recess 19 is provided at the lower surface of the auxiliary fender 16 provided on the side, at a position close to the side of the boat, and the drain port 9 is opened into the recess 19 at the front position close to the bow. since the drain port 19 is made to be invisible from outside by utilizing the secondary fender 16 provided on side, the appearance of the boat is improved. In addition, since the drain port 9 is opened into the recess 19 at the front position close to the bow, the back flow of water into the boat through the port 9 due to a swell can be reduced.