PURPOSE: To enable pumping and water spray by connecting a water discharge cylinder removably to the rear end of a reversibly rotatable rudder cylinder connected to a nozzle at the rear end of a water drum provided with an impeller, and forming the rear end of the water discharge cylinder into upward shape so as to discharge water in the rear direction.

CONSTITUTION: In a small water jet pusher boat, a rudder cylinder 7 rotatable in both directions is connected to a nozzle 6 at the rear end of a water drum 3 provided with an impeller 5 driven by an engine 4. Steering is performed with the water jet direction changed by operating the rudder cylinder 7 to the right or left. In this case, hook protrusions 8 are provided at the rear end right and left parts of the rudder cylinder 7, while hook protrusions 10 are provided at the inner right and left parts of a water discharge cylinder 9, and the water discharge cylinder 9 is fitted to the rear end periphery of the rudder cylinder 7 and twisted to hook protrusions 10 to the hook protrusions 8. The water discharge cylinder 9 can be thus fitted removably to the rear end of the rudder cylinder 7. This water discharge cylinder 9 is formed into upward shape so that the rear end thereof comes out of the water surface and water can be discharged upward to the rear at the time of driving/rotating the impeller 5 by the engine 4.