Propeller Anatomy

• BLADE TIP: The maximum reach of the blade, from the center of the propeller hub.

• LEADING EDGE: The part of the blade nearest the boat, which first cuts through the water, it extends from hub to tip.

• TRAILING EDGE: The part of the blade farthest from the boat.

• CUP: A small curve or lip on the trailing edge of the blade, this allows the propeller to get a better bite on the water. A cup will reduce the engines r.p.m.'s by approximately 200.

5) BLADE FACE: The side of the blade facing away from the boat.

• BLADE BACK: The side of the blade facing the boat.

• BLADE ROOT: The point in which the blades attaches to the hub.

• HUB: On outboards & stern drives, the hub is rubber molded to an inner splined hub to protect the propeller drive system from impact damage and to flex when shifting.

On an inboard propeller, the hub or boss of a propeller is the solid center disc which is bored for the propeller shaft with a keyway that transmits the torque from the shaft to the propeller.

• SOLID HUB: In a solid hub, female splines are machined directly into the hub bore. This is generally used in racing applications.

• DIFUSER RING: The defuser ring aids in reducing exhaust back pressure and in preventingexhaust gas from feeding back into propeller blades. Some difuser rings are made as a solid part of the propeller when it is cast. Others are replaceable aluminum or plastic.

• RIGHT HAND PROPELLER : As you view the Propeller from the stern the leading edge (2) will always be farther away from you than the Trailing Edge (3) . If the leading edges are to your right, the propeller rotates clockwise and is a Right Handed Propeller

If the opposite is true, it is a left-handed propeller.

Right-Handed Propellers are almost, but not quite universal on single engine boats.