MARITIME – PROPULION & PERFORMANCE CALCULATOR
Propeller Pitch Speed
A precise tool.
What is the Propeller Pitch Speed & How does it work?
Propeller pitch is the distance a propeller would move forward in one revolution if there were no slip. It is usually expressed in inches or millimetres and is a key design parameter for matching engine power to hull resistance.
Theoretical speed can be estimated from pitch and shaft revolutions per minute (RPM) using a simple kinematic relationship. By converting the linear advance per minute to nautical miles per hour, the basic formula emerges.
In practice, propeller slip—loss of advance due to water resistance—reduces the actual speed. Incorporating a slip factor yields a more realistic prediction for vessel performance.
V = frac{P times N}{1056} (1 – s)
V = theoretical speed (knots)
Parameters
Result
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Frequently Asked Questions
What is propeller pitch?
Propeller pitch is the distance a propeller would move forward in one revolution if there were no slip, usually measured in inches or millimeters.
How do I calculate theoretical speed from propeller pitch and RPM?
Multiply the propeller pitch by the RPM and divide by 10.8 to get the speed in knots.
What is propeller slip, and why does it occur?
Propeller slip is the loss of advance due to inefficiencies like water resistance and blade angle, reducing the actual speed compared to theoretical calculations.
How does propeller pitch affect boat performance?
A higher pitch increases top speed but reduces acceleration and maneuverability, while a lower pitch provides better acceleration and handling at slower speeds.
What units are used for propeller pitch in this calculator?
Propeller pitch is typically measured in inches or millimeters, depending on the region and manufacturer.
Can I use this calculator for sailboats as well?
While primarily designed for motorized vessels, the basic principles can be applied to understand how propellers affect speed in any watercraft.
What is the relationship between RPM and pitch in determining boat speed?
Boat speed is directly proportional to both RPM and pitch; increasing either will increase the theoretical speed, assuming no slip.
Results are for informational purposes only and do not constitute professional advice.