How To Make Boat Prop Pitch Calculations

Boat prop pitch refers to the distance of the propeller movements with each revolution. Determining the prop pitch will help you decide on the right pitch settings to use and will allow your boat to perform at or closest to its maximum revolution per minute (RPM) potential, thus increasing the boat speed. Here’s how you can calculate the boat prop pitch.

  • Consult your owner’s manual. You need to find out the maximum allowable RPM of your boat when in wide open throttle. Usually measured in feet, the RPM in wide open throttle can be found under the category “Specifications.”
  • Test the actual RPM of your boat. Drive your boat in an open water space. Then, record the RPM it uses when driven in wide open throttle. Make sure to run the boat quarter of a mile. Get the RPM readings from the boat’s tachometer.
  • Do subtractions. You need to subtract the actual RPM from the ideal RPM indicated by the manufacturer. Record the answer, and then deduct 200 RPM from this figure. The number you get from this second deduction is the additional RPM that you need to have.
  • Find out your boat’s prop pitch. Get this information from your propeller’s blade. Using this information, you can decide what kind of propeller to buy for your boat or the right pitch setting to use. Remember that a two-inch increase in the prop pitch can already produce 400 RPM. Choose a new propeller or turn the pitch setting according to the additional RPM you need to make.
  • Use a calculator website. If you need some help in calculating your prop pitch, you can choose to make use of the calculation tools available on the Internet. These websites will require you to provide the measurements of your boat’s prop shaft and prop blade angle. You can get their measurements using a tape measure and a protractor, respectively.
  • Get the help of a professional. If you are not comfortable calculating your boat’s prop pitch on your own, you may consider seeking the help of a professional boat mechanic or a boat expert. He will guide you through the whole procedure and teach you some techniques. Seeking the help of a pro or an expert is especially advisable if this is your first time to own a boat.

If you need to buy a new propeller, make sure to buy according to your boat’s make and your engine’s horsepower. Again, consult your owner’s manual (both for the boat and the engine) or ask for recommendations from boat dealers. There are several considerations you need to remember when choosing a propeller, and they include the propeller’s pitch, diameter, blade pitch and rake angles, number of blades, and materials. Also, consider how you are going to use the boat. If you are going to drive it in an area where the engine will be required to work harder, you need to choose an especially durable propeller. Remember that you need to buy a strong propeller that will improve your boat’s speed and performance, so choose wisely. 


Share this article!

Follow us!

Find more helpful articles: