For safety and efficient performance, it is critical that your engine operates within the RPM range recommended by the manufacturer. Matching the right prop for the load is the most significant factor when choosing a new propeller.

• First, Determine Manufacturer's recommended RPMS: Find the manufacturer's recommended RPM range in the owner's manual or ask your dealer. A reference chart below shows common engine (Outboard and I/O) applications. For information about Inboard Diesel Engines go to www.boatdiesel.com

• Test for Maximum RPM: Using the existing propeller or new propeller, make test runs to determine the maximum RPM and boat speed. Vary the rim angle for optimum performance.
• RPM Higher Than Recommended: if the actual WOT RPM are above the recommended RPM range, install the next large pitch propeller to decrease your WOT RPM. Re-test the WOT RPM.
• RPM Lower Than Recommended: If the actual WOT RPM range is below the recommended range, install the next smaller pitch propeller to increase your WOT RPM. Re-test the WOT RPM. When you combine all these factors, you have the information you need to select the correct propeller for maximum performance, safety, and fuel efficiency.
• Effect of Prop Pitch on RPM: A pitch change increase or decrease the RPM and bring RPM into the recommended range. A 2" increase in pitch (for example. form 21" to 23") typically result in a decrease of approximately 300-400 RPM