Abstract: A jet propelled watercraft having a reverse thrust mechanism including a reverse thrust bucket. The hull is provided with a portion that underlies the discharge nozzle of the jet propulsion unit and which provides a continuous surface for the hull when the reverse thrust bucket is in the forward drive mode. However, when the reverse thrust bucket is moved to the reverse thrust position, a closure panel opens to provide an opening through which water may be discharged during reverse thrust operation.

Abstract: Several embodiments of water jet propulsion units having variable thrust devices by controlling the effective cross sectional area of the discharge nozzle. The rate of acceleration is sensed and the nozzle opening is changed in response to the sensed rate of acceleration.

Abstract: A number of embodiments of cooling systems for marine propulsion units having water cooled internal combustion engines in which the cooling jacket of the engine is at least partially positioned below the level of the water in which the watercraft is operating. The described embodiments all permit draining of the engine cooling jacket when it is not being run. In some embodiments, the drain valve also controls the communication of the coolant from the body of water in which the watercraft is operating with the engine cooling jacket. Various types of pumping arrangements are disclosed for pumping the bilge and automatic valve operation is also disclosed.

Abstract: An assembly for rotatably supporting the propulsion unit of an inboard/outboard marine propulsion system of a watercraft is disclosed. The watercraft includes an engine mounted therein which is drivingly connected to the propulsion unit through a through-hole formed in the transom of the watercraft. The support assembly includes a first bearing arrangement for rotatably supporting the drive from the engine to the propulsion unit and a second, concentrically mounted bearing arrangement for rotatably supporting the propulsion unit relative to the transom. The concentric bearing arrangement permits the propulsion unit to be rotated between above-water and in-water positions while minimizing the length of the propulsion system, thereby conserving space and allowing the propulsion unit to be more compact.

Abstract: A combined manual and automatic steering for a watercraft wherein there is provided an automatic steering control and a manual steering control that is operative to override the automatic control upon manual operator actuation.

Abstract: Two embodiments of improved jet drive units for watercraft wherein the jet drive impeller shaft is coupled to the engine drive shaft by a slip spline connection for facilitating removal of the jet drive unit for servicing without removal of the engine. In addition, an improved connection is provided between the impeller shaft and the impeller that dispenses for the need for splines and thus permits a smaller impeller hub and a greater efficiency jet drive unit.

Abstract: Several embodiment of small boats having improved exhaust systems for precluding the entry of water into the engine combustion chambers from the body of water in which the watercraft is operating. In each embodiment, the exhaust system includes a horizontally extending expansion chamber with an exhaust gas outlet whichis defined by a vertically extending tube in the expansion chamber so as to prevent the likelihood of water reentering the engines through the exhaust system. Several arrangements are disclosed for draining the water from the expansion chamber and the exhaust gases are discharged from the engine into the tunnel around the jet drive unit.

Abstract: Two embodiments of small watercraft incorporating an improved exhaust system for handling the exhaust gases from the engine. In each embodiment, at least one expansion chamber is provided for silencing and cooling the exhaust gases and exhaust gases are delivered from the engine exhaust port to the expansion chamber through a horizontally extending exhaust conduit that has its outlet opening communicating with the expansion chamber at a position spaced substantial distances from the vertically extending side and end walls of the expansion chamber for precluding the likelihood of entry of water into the engine cylinders through the exhaust system. In one embodiment, two such expansion chambers are employed.

Abstract: Several embodiments of water propulsion units for water jet propulsion crafts wherein an improved bearing support is provided for supporting an elongated drive shaft to permit the engine to be positioned well forwardly in the hull. In accordance with each embodiment, the bearing support member is elongated and is affixed rigidly to the jet propulsion unit in a radial direction for facilitating alignment.