A cupped propeller means the blade trailing edges are formed into a curved shape. In appearance, it looks as if the trailing edge was bent upwards into a small radius. Trailing edge cup is incorporated into propeller designs to improve their efficiency when operated on higher speed boats and/or for propellers for turning at high RPM. Typical use might be for example express cruisers with gasoline engines operating at speeds over 30 knots. The propeller will be operating in a cavitating condition. The trailing edge cup allows the cavitating propeller blade to generate more thrust, thus improving propeller efficiency.