Propeller Slip Calculator | Marine Performance Tool
Calculate propeller slip and efficiency based on theoretical and actual boat speed.
Input Method
Enter either the theoretical speed directly, or provide RPM and pitch to calculate it.
How to Use
- Enter either:
- Known theoretical speed directly, or
- Propeller RPM and pitch to calculate theoretical speed
- Enter actual boat speed from GPS or log
- Click Calculate to determine propeller slip
Note: Typical propeller slip is between 10-15%. Values outside this range may indicate propeller damage, fouling, or measurement errors.
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See what's insideFrequently Asked Questions
What is normal propeller slip?
Normal prop slip is 10-15% for most recreational boats. Racing boats may achieve 5-8% slip, while heavy displacement vessels might see 15-25% slip.
How do I reduce propeller slip?
Ensure correct prop pitch and diameter for your boat, keep the prop clean and undamaged, check for ventilation from the hull or trim tabs, and avoid overloading the boat.
What causes high propeller slip?
Common causes include wrong prop pitch/diameter, damaged blades, cavitation, excessive boat weight, fouled hull bottom, or incorrect engine height on the transom.