How to Find the Pitch of an Outboard Prop

When you want to find the pitch of an outboard prop, you don't need to be an expert in marine propulsion systems. The pitch of a boat's propeller is how many inches forward the propeller -- theoretically -- moves a boat with each revolution. It's stamped or cast into the propeller, along with the diameter, as two numbers separated by an "x." A propeller marked "8x12" has a diameter of 8 inches and a pitch of 12 inches. Propellers with a lower pitch provide more torque, useful for towing skiers or water toys. Propellers with higher pitches provide higher top speeds.

Things You'll Need

  • Sturdy object or block of wood
  • 1 1/16-inch box-end wrench or propeller wrench
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Instructions

  1. Exterior Inspection

    • 1

      Inspect the exterior or the propeller. Look on the end of the propeller hub for numbers with the letter "x" centered between them.

    • 2

      Take note of any markings on the propeller blades. Look for the two groups of numbers separated by the "x."

    • 3

      Move to the side of the propeller and inspect the side of the propeller hub. Look for the number groups, divided by the telltale "x."

    In the Interior

    • 4

      Block the propeller with a sturdy object or a block of wood. Use a 1 1/16-inch box-end wrench to remove the propeller nut from the propeller shaft.

    • 5

      Slide the propeller, but nothing more, from the propeller shaft. Turn the propeller around so you can see inside the propeller hub.

    • 6

      Inspect the inside of the propeller hub for the name of the manufacturer and the two groups of numbers -- diameter and pitch, respectively -- separated by an "x."