Propulsion unit for boats

Claim 1

A WATER-PROPULSION UNIT FOR PROPELLING A BOAT, COMPRISING (A) A HOUSING OPERATIVELY CONNECTED TOI SAID BOAT AND HAVING A CHAMBER IN OPEN COMMUNICATION WITH AN INLET FORMED IN THE BOTTOM OF SAID HOUISING AND AN OUTLET ADJACENT THE REAR OF SAID HOUSING, (B) THE BOTTOM OF SAID HOUSING BEING FORMED BY A PLATE SECURED TO THE LOWER END OF SAID HOUSING AND HAVING SAID INLET FORMED THEREIN, (C) SAID PLATE AND HOUSING EXTENDING FORWARDLY OF SAID CHAMBER WITH THEIR FORWARDLY EXTENDING ENDS CURVED UPWARDLY, (D) KEEL MEANS PROJECTING DOWNWARDLY FROM SAID PLATE REARWARDLY OF THE INLET FORMED THEREIN, (E) AN IMPELLER CARRIED IN SAID CHAMBER ABOVE SAID INLET AND HAVING AN AXIS OF ROTATION GENERALLY NORMAL TO THE PLANE OF SAID INLET AND PARALLEL WITH THE PLANE OF SAID OUTLET, (F) DRIVE MEANS FOR ROTATING SAID IMPELLER TO PULL WATER INTO SAID CHAMBER THROGH SAID INLET FOR DISCHARGE THROUGH SAID OUTLET, (G) A CONSTRICTED PASSAGE INTERCONNECTING SAID CHAMBER AND OUTLET WHEREBY SAID WATER IS FORCED OUT OF SAID OUTLET UNDER PRESSURE FOR PROPELLING SAID BOAT, (H) A CUP HAVING A GENERALLY SEMI-CYLINDRICALLY SHAPED LOWER PORTION AND OPERATIVELY CONNECTED TO SAID HOUSING FOR MOVEMENT BETWEEN A RETRACTED POSITION IN WHICH SAID LOWER PORTION IS OUT OF THE LINE OF FLOW OF WATER THROUGH SAID OUTLET AND THE BOAT IS PROPELLED FORWARDLY AND A LOWERED POSITION IN WHICH SAID LOWER PORTION IS IN THE LINE OF FLOW AND THE WATER IS REFLECTED THEREFROM TO PROPEL THE BOAT REARWARDLY, AND (I) MEANS FOR MOVING SAID CUP BETWEEN ITS RETRACTED POSITION AND SAID LOWERED POSITION.