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 propeller. The blades of the propeller are characterized by a blade center axis which corresponds to a generator line of a cone to which the blade, or blade thrust surface, conforms. The propeller hub is fixed to the blade at the root, in line with the blade center axis, such that the hub axis and blade center axis lie in the same plane, and the leading edge of the blade is positioned forward (referring to the upstream direction of movement caused by the propeller) of the trailing edge of the blade.

A propeller having a plurality of blades extending radially outward from a hub, the blades forming a loop. Each loop having an intake portion, an exhaust portion and a tip portion extending radially outward from the hub and a gap between the intake root and the exhaust root. The tip portion of each of the blades is 30%-75% of the blade, the tip portion beginning at a first deviation from zero of the roll value and extending to 90 degrees, wherein roll value is zero in a plane parallel to the hub axis, and wherein the blades have a vertical angle between −45 degrees and 45 degrees throughout.

A propeller having a plurality of blades extending radially outward from a hub, the blades forming a loop. Each loop having an intake portion, an exhaust portion and a tip portion extending radially outward from the hub and a gap between the intake root and the exhaust root. The tip portion of each of the blades is 30%-75% of the blade, the tip portion beginning at a first deviation from zero of the roll value and extending to 90 degrees, wherein roll value is zero in a plane parallel to the hub axis, and wherein the blades have a vertical angle between −45 degrees and 45 degrees throughout.

A propeller having a plurality of blades extending radially outward from a hub, the blades forming a loop. Each loop having an intake portion, an exhaust portion and a tip portion extending radially outward from the hub and a gap between the intake root and the exhaust root. The tip portion of each of the blades is 30%-75% of the blade, the tip portion beginning at a first deviation from zero of the roll value and extending to 90 degrees, wherein roll value is zero in a plane parallel to the hub axis, and wherein the blades have a vertical angle between −45 degrees and 45 degrees throughout.

An outboard motor includes a duct, a propeller, a central shaft, and a plurality of fins. The duct includes a circular hole. The propeller is located in the circular hole. The propeller includes a boss and a plurality of blades radially extending from the boss. The central shaft rotatably supports the propeller. The plurality of fins radially extend from the central shaft and connect the central shaft and the duct. The plurality of fins define an airfoil profile.

An outboard motor includes a duct, a propeller, a central shaft, and a plurality of fins. The duct includes a circular hole. The propeller is located in the circular hole. The propeller includes a boss and a plurality of blades radially extending from the boss. The central shaft rotatably supports the propeller. The plurality of fins radially extend from the central shaft and connect the central shaft and the duct. The plurality of fins define an airfoil profile.

A cantilever fan including a blade and a blade permanent magnet. The blade is clamped at one end to a base and has a distal end which is free to oscillate with distal end having the largest swept displacement of any portion of the blade. The blade extends from the clamped end to the distal end. The blade permanent magnet is attached only to the blade at a point along the blade's length and is free to move with the blade. The fan includes a stationary permanent magnet attached only to the base. The respective locations and relative orientation of the blade permanent magnet and stationary magnet result in a repulsive magnetic force between the blade permanent magnet and stationary magnet. The fan is configured so that the repulsive force increases as the blade's deflection brings the blade permanent magnet closer to the stationary magnet.

A blade made of layered material, such as composite material, configured for exposure to a fluid flow, comprises skins (1, 2) defined between a leading edge (3) and a trailing edge (4) which skins in cross-section form a flow profile. The layered material may consist of several layers of fiber material (5, 5′, . . . ) impregnated with a matrix material, wherein layers of fiber material each comprise a respective body portion (6, 6′, . . . , 13) between and transverse to the skins and each at least a respective skin portion (7, 7′, . . . ; 8, 8′, . . . ) that forms part of the skins. The said skin portions all extend from the related body portion in the direction of the trailing edge. Of said skin portions at least two consecutive skin portions of the one skin overlap and/or two consecutive skin portions of the other skin overlap each other.

A propeller having a plurality of blades extending radially outward from a hub, the blades forming a loop. Each loop having an intake portion, an exhaust portion and a tip portion extending radially outward from the hub and a gap between the intake root and the exhaust root. The tip portion of each of the blades is 30%-75% of the blade, the tip portion beginning at a first deviation from zero of the roll value and extending to 90 degrees, wherein roll value is zero in a plane parallel to the hub axis, and wherein the blades have a vertical angle between −45 degrees and 45 degrees throughout.