Propeller Slip Calculator – Measure Boat Prop Efficiency

Propeller Pitch

Distance the propeller would move forward in one revolution (no slip)

Engine RPM Revolutions per minute at the propeller shaft (after gear reduction)

Gear Ratio ? Engine RPM ÷ Propeller RPM

Actual Boat Speed

Measured speed over water (GPS or log)

Desired Slip (%) Expected propeller slip (0-100%). Typical planing hull: 5-15%, displacement: 15-30%.

Slip %

Estimated Speed --

Theoretical Speed --

Actual Speed --

Propeller Slip --

Propeller Efficiency --