Patent ID: 7517263

Claim:
A watercraft having: a hull; one or more propulsion units attached to the hull; one or more propeller blades rotatably mounted on each said one or more propulsion units for operating in a sub-cavitating mode and a super-cavitating mode, each said blade comprising: an advanced blade section comprising: an upper surface; and a lower surface, the upper surface and the lower surface intersecting at a forward end and at an aft end, wherein the forward end has a forward edge and the aft end has an aft edge, the upper surface having an upper convex portion extending from the forward end to the aft end, and the lower surface having a lower convex portion and a lower concave portion, the lower concave portion and the lower convex portion intersecting at a central zone between the forward end and the aft end, wherein the upper and lower surfaces function to provide fully wetted flow over both the upper and lower surfaces at low speeds, and a partially wetted flow with only a front part of the lower surface fully wetted, at high speeds.