REDUCTION METHOD FOR FLOW WATER PIPE'S OPENING FOR SIDE THRUSTER IN SHIP

PROBLEM TO BE SOLVED: To increase cruise speed and reduce wave shock by horizontally arranging a chord portion of a half-moon shaped disk, welding the upper part of an opening at an elliptic arc portion to block a part of the opening, welding a linear portion of a training wall's roof with the chord portion of the half-moon shaped disk, and welding it with the inner peripheral wall of a flow water pipe at an inner contact portion. SOLUTION: One-third to a half of area of an opening (suction/drainage opening) of both right and left gunwales of a flow water pipe 2 is downward horizontally closed by setting a chord portion of a half-moon shaped disk 5 comprising an elliptic arc portion and the chord portion, and the elliptic arc portion is welded to the upper portion of the opening. A roof is mounted so as to provide rising gradient from the bottom corresponding to the chord portion of the half-moon shaped disk 5 toward the inside of a cylinder of the flow water pipe 2. This roof, as a training wall's roof 6, turns water flow in the flow water pipe 2 from horizontal direction to slightly tilting downward direction, and reduces occurrence of surface flow. Thus, the reduction of the suction/drainage opening (opening) can shrinks a hole on an external plate of a hull, and the reduction of the area of the opening can increase shipping speed and mitigates wave shock.