A propeller includes a bushing that rotates together with the propeller shaft, and a propeller damper disposed around the bushing, and an inner cylinder that surrounds the bushing via the propeller damper. The bushing includes a first cylindrical portion surrounding the propeller shaft, and a first protrusion protruding outward from the first cylindrical portion and integral with the first cylindrical portion. The inner cylinder includes a second cylindrical portion surrounding the bushing via the propeller damper and a second protrusion protruding inward from the second cylindrical portion. The inner cylinder is rotatable with respect to the bushing between a noncontact position and a contact position.

A propeller includes a bushing that rotates together with the propeller shaft, and a propeller damper disposed around the bushing, and an inner cylinder that surrounds the bushing via the propeller damper. The bushing includes a first cylindrical portion surrounding the propeller shaft, and a first protrusion protruding outward from the first cylindrical portion and integral with the first cylindrical portion. The inner cylinder includes a second cylindrical portion surrounding the bushing via the propeller damper and a second protrusion protruding inward from the second cylindrical portion. The inner cylinder is rotatable with respect to the bushing between a noncontact position and a contact position.

A portable propulsion system for a watercraft may include a shaft, a propeller, an outer casing, and a flexible strap. The shaft may have a prop end section, a drive end section, and a rotational axis extending from the prop end section to the drive end section. The propeller may be connected to the prop end section of the shaft. The drive end section may be configured for removable connection to a driver for rotation of the propeller via rotation of the shaft about the rotational axis to propel the watercraft. The outer casing may be disposed around the shaft. The flexible strap may have first and second end sections connected to the outer casing in respective first and second regions.

A portable propulsion system for a watercraft may include a shaft, a propeller, an outer casing, and a flexible strap. The shaft may have a prop end section, a drive end section, and a rotational axis extending from the prop end section to the drive end section. The propeller may be connected to the prop end section of the shaft. The drive end section may be configured for removable connection to a driver for rotation of the propeller via rotation of the shaft about the rotational axis to propel the watercraft. The outer casing may be disposed around the shaft. The flexible strap may have first and second end sections connected to the outer casing in respective first and second regions.

A drive arrangement for a marine vessel. The drive arrangement includes an upper drive part configured to be mounted onto an outside of a transom of the marine vessel. A lower drive part is connected to the upper drive part to be fixed in a vertical direction in relation to the upper drive part. The lower drive part has a hydrodynamic configuration and is provided with at least one propeller. A transmission system is arranged to transfer a drive torque to the propeller from a drive source system connected to the transmission system. An outer surface of the upper drive part substantially is made up of a plurality of surface sections connected by one or more edges. Each of said surface sections has a shape corresponding to a so-called ruled surface that can be generated by the motion of a straight line.

A drive arrangement for a marine vessel. The drive arrangement includes an upper drive part configured to be mounted onto an outside of a transom of the marine vessel. A lower drive part is connected to the upper drive part to be fixed in a vertical direction in relation to the upper drive part. The lower drive part has a hydrodynamic configuration and is provided with at least one propeller. A transmission system is arranged to transfer a drive torque to the propeller from a drive source system connected to the transmission system. An outer surface of the upper drive part substantially is made up of a plurality of surface sections connected by one or more edges. Each of said surface sections has a shape corresponding to a so-called ruled surface that can be generated by the motion of a straight line.

An outboard motor for attachment to a hull of a marine vessel includes a lower case including a propeller shaft to rotate a propeller, and an upper case including a drive shaft to transmit a power to the propeller shaft. The lower case is selected from among different types of lower cases to be attached to the upper case, and the upper case and the lower case are connected by an intermediate structure.

An outboard motor for attachment to a hull of a marine vessel includes a lower case including a propeller shaft to rotate a propeller, and an upper case including a drive shaft to transmit a power to the propeller shaft. The lower case is selected from among different types of lower cases to be attached to the upper case, and the upper case and the lower case are connected by an intermediate structure.

The human powered hydrofoil bicycle includes multiple subsystems integrated together including a structural frame subsystem with associated steering and tiller module, a hydrofoil subsystem to provide vehicle lift, and a powertrain subsystem. The structural frame subsystem may be fitted with buoyancy modules to provide the overall vehicle with a near neutrally buoyant character. The structural frame subsystem also supports a seat for an operator and provides structural support for the steering and tiller module for the hydrofoil subsystem and the drivetrain subsystem. The hydrofoil subsystem includes multiple hydrofoil elements at lowermost portions of the vehicle. These hydrofoil elements generally include in a preferred embodiment a larger rear foil and a smaller front foil. The powertrain subsystem generally includes pedals rotatably supported on the vehicle at a convenient location for engagement and driving by feet of an operator. Power transmission elements extend from the pedals down to a prime mover such as a propeller.

The human powered hydrofoil bicycle includes multiple subsystems integrated together including a structural frame subsystem with associated steering and tiller module, a hydrofoil subsystem to provide vehicle lift, and a powertrain subsystem. The structural frame subsystem may be fitted with buoyancy modules to provide the overall vehicle with a near neutrally buoyant character. The structural frame subsystem also supports a seat for an operator and provides structural support for the steering and tiller module for the hydrofoil subsystem and the drivetrain subsystem. The hydrofoil subsystem includes multiple hydrofoil elements at lowermost portions of the vehicle. These hydrofoil elements generally include in a preferred embodiment a larger rear foil and a smaller front foil. The powertrain subsystem generally includes pedals rotatably supported on the vehicle at a convenient location for engagement and driving by feet of an operator. Power transmission elements extend from the pedals down to a prime mover such as a propeller.