Abstract: A motorboat propeller comprises a hub and a plurality of blades mounted on the hub. The hub comprises peripherally along the axis thereof a front segment, a midsegment and a rear segment. The hub has a hollow interior provided therein with a shaft tube extending along the direction of the axis of the hub and corresponding in location to the midsegment of the hub. The midsegment has a recessed periphery. Located between the inner periphery of the midsegment and the outer periphery of the shaft tube is a connection portion having a correction end to facilitate the work of correcting the position of the center of gravity of the motorboat propeller. The midsegment of the hub can accommodate a greater amount of water for generating a greater backward thrust of water to propel the motorboat.

Abstract: A motorboat water inlet foil grating comprises a frame and a pair of wing pieces. The frame is fastened to the water inlet located at the bottom of a motorboat hull. The wing pieces are mounted obliquely on the frame such that the lower segments of the wing pieces face forward and that the upper segments of the wing pieces face rearward. Each of the wing pieces has a concave upper surface and a convex lower surface. The concave upper surface faces upwards while the convex lower surface faces downwards. The frame is provided with a reinforcing portion for bracing the wing pieces which are capable of guiding water to flow evenly in the water channel of the motorboat so as to enable the propeller of the motorboat to compress the water current efficiently to enhance the forward power of the motorboat.

Abstract: A motorboat impeller comprises an axial portion having a through axial hole and having a plurality of blades mounted around the periphery thereof and further having a plurality of retaining slots in the inner wall of the through axial hole. The retaining slots have a predetermined depth and a predetermined length extending from the front end of the axial portion toward the inside of the axial portion along the direction of the axis of the axial portion. A mounting and dismounting element can be disposed in the retaining slots and is provided with a body of a polygonal construction and having a plurality of retaining blocks extending outwards. The retaining blocks are dimensioned to fit into the retaining slots. The body of the mounting and dismounting element can be held firmly with a hand tool to facilitate the turning of the axial portion.

Abstract: A motorboat impeller comprises an axial portion, a plurality of blades attached to the periphery of the axial portion, an axial casing, and a nose. The axial portion of a conical construction has a front end with an outer diameter smaller than an outer diameter of a rear end thereof and further has a first axial hole extending therethrough. The axial casing is fastened to the inside of the front end of the first axial hole and is harder in quality than the axial portion. The axial casing is provided therethrough with a second axial hole having in the inner wall thereof a plurality of retaining slots engageable with the splines of a driveshaft. The nose of an elastic material is attached to the front end of the axial portion so that the axial portion has a streamline profile.