Abstract: A vertically elongated pump has an intake port at its bottom and a rearwardly directed exhaust port near the bottom. A vertical rod is attached to a piston sliding inside the pump that sucks water in through the intake port and pushes it out the exhaust port. A butterfly valve opens and closes the intake port in cooperation with the motion of the piston. A clamp, attached to the front of the pump, detachably secures the pump to the side of a water borne vessel in a manner that the pump is free to rotate 180.degree. about a vertical axis located outside the body of the pump. The rod is moved up and down by a manually operable handle that can rotate 360.degree. around the vertical axis of the pump, and that can be locked at any position selected.