Propellers and Propulsive Energy

The propeller is on the outside of the boat and is what pushes the boat along in the water. A propeller will have a 'pitch'. The pitch is the distance the propeller would travel if it was put in a box of sand and turned one complete revolution.

The realtionship between the size of the propeller, it's pitch, the engine, etc are crucial and this link will take you to a technical explanation of how propellers work (based on power boats) - courtesy of Real Trawlers