Propeller Sizing Calculator
Calculate optimal propeller diameter and pitch from engine power, hull speed, and shaft RPM.
Inputs
HP
knots
RPM
Results
Propeller Diameter
66.8 in
Pitch
8 in
Diameter (metric)1,696 mm
Pitch Ratio (P/D)0.12
Propeller RPM1,250 RPM
Tip Speed364 ft/s
Estimated Slip15%
How to Use This Calculator
- Enter engine horsepower, target speed in knots, and engine RPM.
- Input the gear reduction ratio from your transmission specifications.
- Review the calculated propeller diameter in inches and pitch in inches.
- Check the pitch ratio (P/D) — values between 0.8 and 1.2 are typical for most vessels.
- Verify tip speed (ft/s) is under 140 ft/s to minimize cavitation and noise.
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