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.

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.

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.

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.

A watercraft and associated pedal drive system are provided. Method of operating the pedal drive are also provided. The pedal drive system allows for unassisted manual pedaling to provide thrust to the watercraft. The pedal drive system also provides on demand pedal assistance of varying levels via an assist drive train having an electric motor to supplement the manual pedal force input provided by a user at the pedals of pedal drive system.

Devices, such as aerodynamic kites used in kiteboarding (also known as kitesurfing), handheld aerodynamic wings used in wing foiling and wing surfing, and paddles used in paddleboarding, for generating a force for powering a user on an appropriately configured vehicle, such as a kiteboard, kitesurfing foilboard, hydrofoil board, surfboard, wing board, wing foil board, stand up paddleboard, stand up paddleboard with hydrofoil, roller skates, rollerblades, skateboards, snowboards, skis, or ice skates, to traverse across a body of water, sand, earth, paved area, snow, or ice, are provided with a thrust generating device (e.g., an electric ducted fan system) to assist in generating said force.

Devices, such as aerodynamic kites used in kiteboarding (also known as kitesurfing), handheld aerodynamic wings used in wing foiling and wing surfing, and paddles used in paddleboarding, for generating a force for powering a user on an appropriately configured vehicle, such as a kiteboard, kitesurfing foilboard, hydrofoil board, surfboard, wing board, wing foil board, stand up paddleboard, stand up paddleboard with hydrofoil, roller skates, rollerblades, skateboards, snowboards, skis, or ice skates, to traverse across a body of water, sand, earth, paved area, snow, or ice, are provided with a thrust generating device (e.g., an electric ducted fan system) to assist in generating said force.

A marine propulsion unit of a marine vessel includes a casing provided to house the steering shaft and a controller configured or programmed to control driving of a propeller, the casing being rotatable by the steering shaft, a power supply wire to supply power to the stator, and a signal wire to transmit a drive signal to the controller. The power supply wire and the signal wire are located outside and along the casing so as to pass behind the steering shaft from a first side to a second side of the casing, the first and second sides being opposite to each other with respect to a forward-rearward direction in a plan view thereof.

A marine propulsion unit of a marine vessel includes a casing provided to house the steering shaft and a controller configured or programmed to control driving of a propeller, the casing being rotatable by the steering shaft, a power supply wire to supply power to the stator, and a signal wire to transmit a drive signal to the controller. The power supply wire and the signal wire are located outside and along the casing so as to pass behind the steering shaft from a first side to a second side of the casing, the first and second sides being opposite to each other with respect to a forward-rearward direction in a plan view thereof.

This present invention relates to an electric fin and a water sports instrument, wherein the electric fin comprises a housing extending along a first direction and having a water inlet cavity; and a propeller and a guide member sequentially arranged in the first direction, wherein the propeller is located in the water inlet cavity, at least part of the guide member is located in the water inlet cavity, the water flow in the water inlet cavity flows out of the guide member; the propeller is provided with a propeller shaft and a plurality of blades, the propeller shaft extends in the first direction, and the plurality of blades are arranged on the propeller shaft in the circumferential direction; the guide member is provided with a guide shaft and a plurality of flow deflectors, the guide shaft extends in the first direction and the plurality of flow deflectors are arranged on the guide shaft in the circumferential direction; the outer contour enclosed by the propeller shaft and the guide shaft shows a projection in a second direction, whose size in a third direction gradually decreases along a fourth direction. The electric fin of the present invention has sufficient power and good guiding performance.