A marine engine assembly for mounting to a watercraft is disclosed. The marine engine assembly has an engine unit, an exhaust system fluidly and a propulsion device. The engine unit includes an engine unit housing, an internal combustion engine and an air intake assembly. The air intake assembly, at least one combustion chamber, and the exhaust system together defining at least in part a gas flow pathway. A sealing valve is provided in the gas flow pathway. The sealing valve has an open position permitting flow of gas therethrough. The sealing valve has a closed position preventing flow of gas therethrough for sealing a portion of the gas flow pathway downstream of the sealing valve from a portion of the gas flow pathway upstream of the sealing valve. An air pump is configured for supplying air to the gas flow pathway downstream of the sealing valve.

An electric underwater jet motor designed for vehicles traveling above or below the sea. The electric underwater jet motor includes a plurality of stators for marine crafts; at least one radial stator, at least one rotor, at least two impeller blades, a magnetic bearing; at least one permanent magnet bar; at least one axial stator, hydrodynamic bearing components, a motor housing and an engine fastener; a hydrodynamic jet motor housing; and a control unit including a microprocessor, a software, magnetic bearing distance sensors, counter and speed measurement sensors, gyroscopic balance sensors to provide comfortable travel by collected data to reduce an effect of sea currents and wave movements which are the consequences of seasickness on the passengers at sea, heat and humidity sensors, pressure measurement sensors, voltage and ampere measurement sensors, a motor drive circuitry, software algorithms, an energy management system, a control panel, batteries and battery charging components.

A propeller drive assembly includes a driveshaft for transferring a torque between an engine and a propeller of a water surface vessel, and a housing enclosing the driveshaft. The assembly includes, separately from the driveshaft, a first element and a second element, the first element extending through a first bore of the second element, wherein one of the first and second elements is fixed to the driveshaft and the other of the first and second elements is arranged to be stationary in relation to the housing, and the one of the first and second elements which is fixed to the driveshaft presents in the first bore a first elongated cavity forming a first helix along the first bore, so as to form with the other of the first and second elements a screw pump.

There is provided an outboard motor. In a posture in use of the outboard motor, an oil filter is inclined such that a mounting portion side is located lower than a tip end side and the mounting portion side is located at an inner side and a tip end side is located at an outer side in the width direction of the outboard motor, a cover mating position between an upper engine cover and a lower engine cover is set to a position lower than an upper part of the tip end, and is higher than a lower part of the mounting portion, and an electric actuator is mounted on a lower part of an engine block and is mounted on a position closer to a center of the engine relative to a position of an outermost end of the oil filter in a width direction of the engine.

An outboard engine for propelling a boat includes a propulsion unit with an electric motor, a propeller driven by means of the electric motor, a control unit for controlling the power of the electric motor, and a water detection means. The water detection means is adapted to detect whether the propeller is submersed in water. The power of the electric motor can be influenced via the control unit based on the detection.

A low emission submersible engine is part of a multipurpose aquatic device, such as an aquatic craft or an electrical generator. A propulsion system having a propeller is coupled to the submersible engine to produce a swimmer propulsion machine and a generator is attached to the engine to produce an electrical generator. The submersible engine receives air from a snorkel that extends up above a water line. The aquatic device has a fuel reservoir which may receive liquid fuel or may receive a fuel cylinder. Floatation chambers keep the aquatic device afloat with the engine submerged. The exhaust assembly and exhaust ports from the engine may also be submerged and the exhaust ports may provide additional thrust. A propulsion system housing integrates the drive shaft and propeller, clutch coupler, exhaust conduits and water flow conduits and is detachably attachable to the engine.

Systems and methods are for monitoring underwater impacts to marine propulsion devices. The systems can comprise a marine propulsion device that is trimmable up and down about a trim axis; a trim sensor that senses at least one of a current trim position of the marine propulsion device relative to the trim axis and a rate at which the marine propulsion device is trimmed relative to the trim axis; and a controller that is configured to compare the rate at which the marine propulsion device is trimmed relative to the trim axis to a stored threshold value to thereby determine whether an underwater impact to the marine propulsion device has occurred.

A marine propulsion system includes a first marine propulsion device and a second marine propulsion device. The first marine propulsion device includes an engine, a first propeller shaft to receive a driving force from the engine, and a first controller configured or programmed to control the engine. The second marine propulsion device includes an electric motor, a second propeller shaft to receive a driving force from the electric motor, an electric circuit connected to the electric motor to drive the electric motor, and a second controller configured or programmed to control the electric motor. The first controller is configured or programmed to put a limitation on an output of the engine when the electric motor is not being driven.

A marine propulsion system includes a first marine propulsion device and a second marine propulsion device. The first marine propulsion device includes an engine, a first propeller shaft to receive a driving force from the engine, and a first controller configured or programmed to control the engine. The second marine propulsion device includes an electric motor, a second propeller shaft to receive a driving force from the electric motor, an electric circuit connected to the electric motor to drive the electric motor, and a second controller configured or programmed to control the electric motor. The first controller is configured or programmed to put a limitation on an output of the engine when the electric motor is not being driven.

An outboard motor unit includes a first outboard motor including a supercharger that is located inside a first cowling and supplies compressed air to a first engine, a second outboard motor including a second cowling and a second engine housed in the second cowling, and an air passage through which the air compressed by the supercharger of the first outboard motor is supplied to the second engine of the second outboard motor.