A marine propulsion system for shallow waters, swamps, savannahs and the like includes a rotating propeller shaft supporting a propeller. An anti-cavitation body defines a partial cylinder having a longitudinal axis adjacent to the propeller. The propeller generates a vacuum between the anti-cavitation body and a surface of a water body. First and second wings adjacent to edges of the anti-cavitation body are generally planar and operatively angled towards the bottom of a water body. The first and second wings are adjusted to run below the water body surface and seal the anti-cavitation body to maintain generated vacuum. A first thread is cut in a first helical direction at an end of the rotating propeller shaft adjacent the propeller, and slightly more distal therefrom a second thread is cut in a second helical direction opposed to the first thread helical direction. The second thread drives matter away from the bearing.

A marine propulsion unit includes a propeller that rotates around a rotation axis of a propeller shaft, a case in which the propeller shaft is disposed, and a skeg that extends downward from the case. The skeg includes a reinforcer with a mechanical strength greater than that of a base material of the skeg.

A marine propulsion unit includes a propeller that rotates around a rotation axis of a propeller shaft, a case in which the propeller shaft is disposed, and a skeg that extends downward from the case. The skeg includes a reinforcer with a mechanical strength greater than that of a base material of the skeg.

An outboard motor for a marine vessel application, and related methods of making and operating same, are disclosed herein. In at least one embodiment, the outboard motor includes a horizontal-crankshaft engine in an upper portion of the outboard motor, positioned substantially positioned above a trimming axis of the outboard motor. In at least another embodiment, first, second and third transmission devices are employed to transmit rotational power from the engine to one or more propellers at a lower portion of the outboard motor. In at least a further embodiment, the outboard motor is made to include a rigid interior assembly formed by the engine, multiple transmission devices, and a further structural component. In further embodiments, the outboard motor includes numerous cooling, exhaust, and/or oil system components, as well as other transmission features.

An outboard motor for a marine vessel application, and related methods of making and operating same, are disclosed herein. In at least one embodiment, the outboard motor includes a horizontal-crankshaft engine in an upper portion of the outboard motor, positioned substantially positioned above a trimming axis of the outboard motor. In at least another embodiment, first, second and third transmission devices are employed to transmit rotational power from the engine to one or more propellers at a lower portion of the outboard motor. In at least a further embodiment, the outboard motor is made to include a rigid interior assembly formed by the engine, multiple transmission devices, and a further structural component. In further embodiments, the outboard motor includes numerous cooling, exhaust, and/or oil system components, as well as other transmission features.

An outboard motor for a marine vessel application, and related methods of making and operating same, are disclosed herein. In at least one embodiment, the outboard motor includes a horizontal-crankshaft engine in an upper portion of the outboard motor, positioned substantially positioned above a trimming axis of the outboard motor. In at least another embodiment, first, second and third transmission devices are employed to transmit rotational power from the engine to one or more propellers at a lower portion of the outboard motor. In at least a further embodiment, the outboard motor is made to include a rigid interior assembly formed by the engine, multiple transmission devices, and a further structural component. In further embodiments, the outboard motor includes numerous cooling, exhaust, and/or oil system components, as well as other transmission features.

An outboard motor for a marine vessel application, and related methods of making and operating same, are disclosed herein. In at least one embodiment, the outboard motor includes a horizontal-crankshaft engine in an upper portion of the outboard motor, positioned substantially positioned above a trimming axis of the outboard motor. In at least another embodiment, first, second and third transmission devices are employed to transmit rotational power from the engine to one or more propellers at a lower portion of the outboard motor. In at least a further embodiment, the outboard motor is made to include a rigid interior assembly formed by the engine, multiple transmission devices, and a further structural component. In further embodiments, the outboard motor includes numerous cooling, exhaust, and/or oil system components, as well as other transmission features.

A propulsion apparatus includes a screw, a unit case, an anti-cavitation plate, a heat generation portion, and a cooling liquid passage. The screw is submerged in outside water and generates a propulsion force. The unit case accommodates at least a power transmission mechanism which transmits power from a drive source to the screw. The anti-cavitation plate is arranged on the unit case at a higher position than the screw, and at least part of the anti-cavitation plate is submerged in outside water. The heat generation portion is arranged at an inside or an outside of the unit case. The cooling liquid passage causes a cooling liquid to flow to the heat generation portion. Part of the cooling liquid passage is arranged within the anti-cavitation plate.

A propulsion apparatus includes a screw, a unit case, an anti-cavitation plate, a heat generation portion, and a cooling liquid passage. The screw is submerged in outside water and generates a propulsion force. The unit case accommodates at least a power transmission mechanism which transmits power from a drive source to the screw. The anti-cavitation plate is arranged on the unit case at a higher position than the screw, and at least part of the anti-cavitation plate is submerged in outside water. The heat generation portion is arranged at an inside or an outside of the unit case. The cooling liquid passage causes a cooling liquid to flow to the heat generation portion. Part of the cooling liquid passage is arranged within the anti-cavitation plate.

An outboard drive assembly for a work boat is provided. In embodiments, an outboard drive assembly includes a lower outdrive assembly including: a housing extending between a first and end a second end and having a motor housed therein; a propeller mounted to the first end of the housing; first and second fins extending horizontally from opposing side portions of the motor housing; a third fin extending vertically from the housing; respective cutting blades attached to respective end portions of each of the first, second and third fins adjacent the propeller; an upper outdrive assembly including mounting brackets configure to connect the upper drive assembly to a deck of a work boat; and a drive arm assembly pivotally mounted to the lower outdrive assembly at a first end of the drive arm assembly and mounted to the upper outdrive assembly at a second end of the drive arm assembly.