PURPOSE: To obtain relatively powerful reverse thrust with a simplified structure, in the case of a water jet propulsion machine which has a pump case provided on the rear of a conduit duct for forming a conduit tube and has an impeller rotatably supported in a pump case so as to generate jet stream and also has jet nozzles provided in series whose diameters more throttled toward the rear.
CONSTITUTION: The side wall of a jet nozzle 11 is provided with an opening 17 and a flapper valve 18 capable of opening and closing the opening 17 is pivoted thereto and an impeller 10 has a driving means 12 connected thereto so that it can make switching between a normal rotating operation for injecting jet stream rearward and a reverse rotating operation for injecting jet stream forward.
IKEDA TOSHIMITSU
KITA MASATO
