A marine propulsion system includes marine propulsion devices each including a propeller shaft, an engine, an electric motor, a power transmission, an inverter, a voltage sensor, and a controller. The power transmission transmits mechanical power to the propeller shaft from at least one of the engine and the electric motor. The inverter outputs electric power inputted thereto to the electric motor after converting the electric power. The voltage sensor detects induced voltage generated by the electric motor. The controller executes a protection control to protect the inverter when the induced voltage is greater than a first threshold while the electric motor is not being driven.

A marine propulsion system includes marine propulsion devices each including a propeller shaft, an engine, an electric motor, a power transmission, an inverter, a voltage sensor, and a controller. The power transmission transmits mechanical power to the propeller shaft from at least one of the engine and the electric motor. The inverter outputs electric power inputted thereto to the electric motor after converting the electric power. The voltage sensor detects induced voltage generated by the electric motor. The controller executes a protection control to protect the inverter when the induced voltage is greater than a first threshold while the electric motor is not being driven.

Example steering control systems for multiple devices are provided herein. A system includes a trolling motor assembly having a propulsion motor and a steering actuator and a sonar assembly comprising a transducer assembly and a directional actuator. The system further includes a user input assembly that is configured to detect user activity related to controlling operation of the trolling motor assembly and operation of the sonar assembly. The system further includes a processor that is configured to determine a direction of turn based on user activity, generate an electrical turning input signal indicating the direction of turn, and direct one of the steering actuator and the directional actuator, via the turning input signal, to rotate one of the propulsion motor and the transducer assembly, respectively, in a direction of turn based on the turning input signal.

Methods and systems for operating powersport vehicles during an operator-vehicle separation condition are provided. One method includes detecting the operator-vehicle separation condition using a first tetherless criterion and a second tetherless criterion. In response to detecting the operator-vehicle separation condition using both the first tetherless criterion and the second tetherless criterion, the method includes preventing propulsion of the powersport vehicle.

Methods and systems for operating powersport vehicles during an operator-vehicle separation condition are provided. One method includes detecting the operator-vehicle separation condition using a first tetherless criterion and a second tetherless criterion. In response to detecting the operator-vehicle separation condition using both the first tetherless criterion and the second tetherless criterion, the method includes preventing propulsion of the powersport vehicle.

A marine drive unit for a boat includes a cooling compartment arranged in a drive unit body. The cooling compartment forms part of a closed cooling circuit, where the cooling circuit is arranged to cool propulsion components of the boat, where the cooling compartment comprises an inlet opening, an inlet channel, a lower end, an outlet channel and an outlet opening, where the inlet channel forms a first flow path for a cooling fluid from the inlet opening to the lower end of the cooling compartment. The outlet channel forms a second flow path for the cooling fluid from the lower end of the cooling compartment to the outlet opening, thereby allowing heat from the cooling fluid to dissipate through the outer wall of the drive unit.

A marine drive unit for a boat includes a cooling compartment arranged in a drive unit body. The cooling compartment forms part of a closed cooling circuit, where the cooling circuit is arranged to cool propulsion components of the boat, where the cooling compartment comprises an inlet opening, an inlet channel, a lower end, an outlet channel and an outlet opening, where the inlet channel forms a first flow path for a cooling fluid from the inlet opening to the lower end of the cooling compartment. The outlet channel forms a second flow path for the cooling fluid from the lower end of the cooling compartment to the outlet opening, thereby allowing heat from the cooling fluid to dissipate through the outer wall of the drive unit.

Embodiments of a portable propulsion facilitation device and system for a marine vessel provide a rechargeable power source and a removable trolling motor mounting base securable to a marine vessel. In various embodiments, the power source employs rechargeable batteries that are secured within a cover. The device can include an access door that permits a user to access the power source when removal or replacement is necessary. The power source can be maintained within a housing of a trolling motor or one or more housings secured to the mounting base. In various embodiments, the mounting base is integrated with, or attachable to, one or more tubes, wherein the tube(s) can be secured and/or placed in a traditional fishing rod holder or other opening on the vessel. A trolling motor can be secured to the mounting base.

A fluid machine includes: a shaft portion; a shroud surrounding the shaft portion and including an inside surface that forms a flow path-forming surface defining a flow path with the shaft portion; a first propeller rotatably provided in the flow path; a second propeller rotatably provided on a downstream side of the first propeller in the flow path; and a motor including a rotor that is fixed to an outer circumferential portion of the second propeller and that is accommodated in the shroud, and a stator that surrounds the rotor via a clearance and that is fixed in the shroud. A portion of the flow path-forming surface on a downstream side of the second propeller decreases in diameter toward the downstream side, and the shroud includes an inlet flow path that is open at a portion between the first propeller and the second propeller of the flow path-forming surface.

An aircraft propulsion system includes at least first and second electrical generators, each being configured to provide electrical power to a respective first and second AC electrical network. The system further comprises at least first and second AC electrical motors directly electrically coupled to a respective AC network and coupled to a respective propulsor, and a DC electrical network electrically coupled to the first and second AC networks via respective first and second AC to DC converters, and to a further electrical motor, the further electrical motor being coupled to a propulsor.