PURPOSE: To attain remarkably improved capability of stem to drive away waves by providing a continuous step around the stem end.

CONSTITUTION: A step 7 is formed by making hull plate 1 above the waterline swell outward. This step is provided at both sides of the boat continuously from the stern to the stem and also around the stem end forming a continuous curve all around the boat. A sleigh member 71 of the stem is touched against the step 7, so that the configuration of the stem as viewed from the side of hull constitutes a continuous line. Slanting walls 20 are formed at both ends of the cockpit floor 2 between this floor and vertical walls 21. A lounge 10 is also constructed in smooth alignment with the floor 2 and the slanting walls 20 to support load of this portion. The upper end of walls at both sides of a stern opening 8 are bent inward forming rounded brim 81, but no such brim is formed at the lower end of the stern gunwale 9 which serves as a back wall of the opening 8.