What Is Propeller Pitch?

Published: 12/18/12 at 01:03pm

The theoretical pitch of a propeller is the distance it would move forward if it were cutting through a solid. It’s like a screw, a 16” diameter propeller with an 11” pitch would move forward 11” in one rotation, if it were cutting through Jell-O. Of course in the water it never goes this far, because water isn't a solid. In the water it goes only about 50% of that distance.

So why do we use pitch if it isn't the actual distance the propeller travels? Basically it is a reference point that through experience we know that a specific diameter and pitch will load an engine correctly. To size a propeller we need to know the following:

  1. Boat Make and Model
  2. Engine Make and Model
  3. Transmission Reduction Ratio
  4. Limitation in space for the propeller if any
  5. Diameter and taper of the propeller shaft

With these 5 things we can provide you with a propeller that will load the engine as it is designed and provide efficient propulsion.

Sizing propellers is part science and part art. After 27 years of doing this I am still learning, and that is what makes the job fun.

Fred Hutchison