Abstract: A power boat propulsion system installed in a power boat having a waterway in the stern, an engine on the inside, and a shaft coupled to the engine and inserted through the waterway, includes a barrel-like impeller duct fixedly fastened to the rear outlet of the waterway, an impeller pivoted to the inside of the impeller duct and connected to the shaft for synchronous rotation with the shaft, a stator mounted inside the impeller duct and adapted for supporting a rear end of the shaft, and a rudder mounted inside the impeller duct near a rear outlet of the impeller duct. The rudder has top and bottom sides thereof pivoted to the impeller duct for deflection leftwards and rightwards.

Abstract: A boat propeller comprises a hub formed of a front cylindrical member and a rear cylindrical member. The hub is provided in the joining place with a plurality of receiving cavities which are arranged equiangularly and circularly. Each cavity is provided removably with an angle setting member which is joined with the hub. A plurality of blades are joined with the outer periphery of the hub such that the inner ends of the blades are inserted into the cavities and are located by the angle setting members. Under the circumstance that the shapes of the hub and the blades remain unchanged, the blade pitch in relation to the hub can be changed by the angle setting members of various shapes.

Abstract: A boat propeller comprises a hub formed of a front cylindrical member and a rear cylindrical member. The hub is provided in the joining place with a plurality of receiving cavities which are arranged equiangularly and circularly. Each cavity is provided removably with an angle setting member which is joined with the hub. A plurality of blades are joined with the outer periphery of the hub such that the inner ends of the blades are inserted into the cavities and are located by the angle setting members. Under the circumstance that the shapes of the hub and the blades remain unchanged, the blade pitch in relation to the hub can be changed by the angle setting members of various shapes.

Abstract: A boat propelling system is mounted in a water channel of the boat hull and composed of an engine, a transmission shaft driven by the engine, an impeller driven by the transmission shaft and provided with blades, a stator mounted behind the impeller and provided with stator vanes, and a nozzle located behind the stator. The impeller blades and the stator vanes are separated by a gap adjustable by the magnitude of jet flow of water.

Abstract: A propeller is made up of a propelling unit having a plurality of blades, a driving unit for driving the propelling unit, and a plurality of deformable transmission units located between the propelling unit and the driving unit such that the transmission units are retained in the retaining slots of the propelling unit and the driving unit. The transmission units are tubular in shape and capable of deforming to absorb an impact force exerting on the transmission units in a direction perpendicular to the longitudinal axis of the transmission units, so as to safeguard the structural integrity of the propeller at such time when the propeller in motion is impacted on by a foreign object.

Abstract: A powerboat propelling system is composed of an engine, a water tract, a propeller, and a stator. The water tract is provided with a water inlet, a nozzle having a water outlet, and a midsection in which the propeller is mounted. The stator is composed of a frame, an axial portion, and a plurality of stator blades fastened with the frame and the axial portion. The axial portion has a front segment and a rear segment. The front segment and the frame form therebetween a first circular space forming a portion of the water tract, whereas the rear segment and the nozzle form therebetween a second circular space forming a portion of the water tract. The first and the second circular spaces have a cross-sectional area which becomes gradually smaller from one end thereof toward another end thereof contiguous to the nozzle for accelerating the flow of water in the water tract without increasing the length of the stator or nozzle.

Abstract: A motorboat propelling system is composed of a water current channel in which a propeller and a stator are located. The channel is provided at a head end thereof with a water inlet and at a tail end thereof with a propelling nozzle. The stator has an axial portion divided into a front section contiguous to the propeller and a rear section contiguous to the nozzle. The front section has an outer diameter becoming progressively smaller towards one end thereof contiguous to the propeller, whereas the rear section has an outer diameter becoming gradually smaller towards one end thereof contiguous to the propelling nozzle.

Abstract: A device for removing gas and impurities from the molten aluminium is composed of a driving portion, a transmission portion, and an agitating portion. The driving portion has an output shaft while the transmission portion has a transmission shaft such that the axis of the transmission shaft is parallel to the axis of the output shaft, and that the transmission shaft is driven by the output shaft. The agitating portion comprises a plurality of blades, which are driven by the transmission shaft. Each blade has an upper end surface and a lower end surface, which form respectively a predetermined angle with the axis of the transmission shaft. The transmission shaft is provided with an axial hole of a predetermined length. Each blade is provided therein with a channel for expelling the gas contained in the molten aluminium.

Abstract: The impeller includes a hollow shaft member screwing therein and thereto a hollow fixing shaft rotatably mounted in nozzle of a motorboat having a propeller shaft projecting into the nozzle to drive the fixing shaft, in which the shaft member has a truncated cone-shaped leading end having a cross-sectionally polygonal inner hole.