PURPOSE: To facilitate the draining of bilge and to strengthen a centerboard part by making the part of the cockpit higher in front of a scupper.

CONSTITUTION: The scupper 9 is provided at the lower part of the cockpit 3, and a centerboard case 6 is provided for mounting the centerboard 4. The heights of a front floor board 7 in front of the scupper 9 and side floor 10 are higher than the cockpit floor board 8. Since the scupper 9 is located at the lowest part, the draining of the bilge is easy. Because the floor board of the cockpit has the double structure, the strength of the part on which the centerboard is mounted can be increased.