PURPOSE: To produce higher propulsion force by giving the outside of an impel ler a deflection plate which extends tangentially and defines a water inlet and a water outlet, and fitting a bent deflection plate guiding water at the end part of an impeller.

CONSTITUTION: A pump 3 is provided with a casing sucking water or a deflection plate 5. Water passes through an opening part in the tangential direction from a forward range and runs along an impeller 2. The water may pass through the end part of an impeller 2 from the forward range so as to be sucked, or may be sucked by a tubular bent member going to the inside of a hollow shaft. All water, after being sucked, is centrifugally-carried rearwards between the wall and casing of a ship. The shaft of the impeller 2 of the pump 3 is disposed perpendicularly to the longitudinal axis of the ship, and fitted tangentially onto the wall of a hull 1.