PURPOSE: To obtain a hull which can travel freely on the water surface by arranging a weight in the lower part of the vacant hull which is made of FRP and transmitting each turning force of a handle and a pedal by an operator to the screw and the rudder in the stern part through flexible shafts.

CONSTITUTION: A hull 1 whose front and rear parts are formed gradually slender and top edge is made sharp is made of FRP, and its inside is made vacant. A weight chamber 5 is formed in the lowest part under the water surface, and a weight 6 is installed in the weight chamber 5. The turning force of a handle 9 and the revolution driving force of a pedal 12 by an operator on a seat 8 are transmitted to the rudder 25 and a screw 19 in the stern part through flexible shafts 14 and 21, and thus a light hull which can travel freely on the water surface can be obtained. More stable hull can be obtained by forming a constricted part on the draft line part between the over-water-surface part 2 and the under-water-surface part 3 of the hull 1.