Marine Propeller Slip Calculator
Compare entered speed with the geometric pitch-speed model.
A QUICK WALKTHROUGH
How to use this tool
- Enter all values in the stated units.
- vtheoretical=pitch×0.0254×propeller rpm/60 (m/s); convert to knots using 1 kn=1852/3600 m/s. Apparent slip=100(1−vactual/vtheoretical). Pitch>0 in inches/revolution, propeller speed>0 rpm, actual speed≥0 knots, using the same speed reference. Enter propeller rpm, not engine rpm. This is pure geometry, with no current, wake or hydrodynamic corrections; it is not propeller selection or efficiency. Negative apparent slip is preserved.
- Calculate
Formula and assumptions
vtheoretical=pitch×0.0254×propeller rpm/60 (m/s); convert to knots using 1 kn=1852/3600 m/s. Apparent slip=100(1−vactual/vtheoretical). Pitch>0 in inches/revolution, propeller speed>0 rpm, actual speed≥0 knots, using the same speed reference. Enter propeller rpm, not engine rpm. This is pure geometry, with no current, wake or hydrodynamic corrections; it is not propeller selection or efficiency. Negative apparent slip is preserved.
Inputs stay in this browser.
Inputs stay in this browser.
GOOD TO KNOW
Common questions
How is the result calculated?
vtheoretical=pitch×0.0254×propeller rpm/60 (m/s); convert to knots using 1 kn=1852/3600 m/s. Apparent slip=100(1−vactual/vtheoretical). Pitch>0 in inches/revolution, propeller speed>0 rpm, actual speed≥0 knots, using the same speed reference. Enter propeller rpm, not engine rpm. This is pure geometry, with no current, wake or hydrodynamic corrections; it is not propeller selection or efficiency. Negative apparent slip is preserved.