To provide a propeller for a boat propulsion apparatus, which propeller is excellent in maintainability including easy assembly and easy disassembly and reliably reduces the impact force caused by colliding with an obstacle and transmitted to the hub and the output shaft of the boat propulsion apparatus. The propeller includes: a shaft sleeve insertably and removably fixed to an output shaft of the boat propulsion apparatus; a plurality of blade components that are individually supported by the shaft sleeve and are arranged at intervals in a rotation direction of the output shaft; and a plurality of dampers disposed in such a manner that each of the plurality of dampers is disposed between adjacent two of the plurality of blade components.

A marine drive has a propulsion unit, a supporting cradle, a resilient mount that couples the propulsion unit to the supporting cradle, a sound blocking member that extends across an internal gap between the propulsion unit and the supporting cradle, and a cowling system having upper and lower cowlings that cover at least a portion of the propulsion unit and lower cradle covers that cover at least a portion of the supporting cradle. The upper and lower cowlings are separated from the lower cradle covers by an external gap so that the upper and lower cowlings can move along with the propulsion unit and with respect to the supporting cradle and the cradle covers. The sound blocking member blocks the sound which otherwise would emanate from propulsion unit via the internal gap and then from the marine drive via the external gap.

The propulsion unit includes a frame construction having an upper portion forming a support arm protruding from a hull of the vessel and a lower portion forming a longitudinal compartment provided with a propeller shaft having at least one propeller attached thereto, and a first electric motor driving the propeller shaft. The method includes measuring vibrations of the propulsion unit with at least one measuring device, forming a first auxiliary torque control signal based on the measured vibration signal, adding the first auxiliary torque control signal to a first torque control signal produced by a first torque controller of the first electric motor. The first auxiliary torque signal acts against the measured vibrations.

The propulsion unit includes a frame construction having an upper portion forming a support arm protruding from a hull of the vessel and a lower portion forming a longitudinal compartment provided with a propeller shaft having at least one propeller attached thereto, and a first electric motor driving the propeller shaft. The method includes measuring vibrations of the propulsion unit with at least one measuring device, forming a first auxiliary torque control signal based on the measured vibration signal, adding the first auxiliary torque control signal to a first torque control signal produced by a first torque controller of the first electric motor. The first auxiliary torque signal acts against the measured vibrations.

The embodiment relates to a balanced propeller and to an extrudable metal polymer composite and process for making and using the composite to make balancing weight strips for marine or boat propellers. Metal particulate of adequate particle size is mixed with a polymer that is extruded or injection molded to form a high-density weighted strip.

There is provided mechanisms for controlling movement of a propeller shaft on a vessel. A controller includes processing circuitry. The processing circuitry is configured to cause the controller to detect movement of the propeller shaft by determining a signature of a sustained oscillation of the propeller shaft. The processing circuitry is configured to cause the controller to control movement of the propeller shaft according to the determined signature.

There is provided mechanisms for controlling movement of a propeller shaft on a vessel. A controller includes processing circuitry. The processing circuitry is configured to cause the controller to detect movement of the propeller shaft by determining a signature of a sustained oscillation of the propeller shaft. The processing circuitry is configured to cause the controller to control movement of the propeller shaft according to the determined signature.

A reduced noise curved surface, including the elements of a curved substrate and a plurality of micropillars operationally connected to the curved substrate and defining a coating, wherein the respective micropillars are positioned to define an aperiodic sequence based on the golden ratio, and wherein the plurality of aperiodically sequenced micropillars increase sound absorption and drag reduction of the curved surface.

A reduced noise curved surface, including the elements of a curved substrate and a plurality of micropillars operationally connected to the curved substrate and defining a coating, wherein the respective micropillars are positioned to define an aperiodic sequence based on the golden ratio, and wherein the plurality of aperiodically sequenced micropillars increase sound absorption and drag reduction of the curved surface.

A damper is disposed between an outer peripheral surface of a bushing and an inner peripheral surface of an inner hub. The damper includes a first portion facing a rib of the bushing, a second portion facing a rib of the inner hub, and a connection portion by which the first portion and the second portion are connected to each other. In a state in which a rotational force has not been applied between the bushing and the inner hub, the damper includes a cross-sectional shape that defines a deformation-absorbing space positioned between the first portion and the second portion. The deformation-absorbing space is deformed such that the first portion approaches the second portion in a state in which the rib of the bushing and the rib of the inner hub have moved relatively by application of a rotational force between the bushing and the inner hub.