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Propeller Pitch Speed and Slip

Calculate propeller pitch speed and slip with local equations, selectable units and supported inverse relationships.

  • Formula & worked example
  • Private in your browser
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

theory speed = 22.86; prop slip = 12.510936. Values use the worked example unit selections.

Videal(mph) = pitch(in) × rpm/(1056 × gear ratio); slip = 1−Vactual/Videal

Worked example

Enter these known values and leave the other values blank.

Engine/crankcase rpm
3000 rpm
Gear ratio
2 : 1
Propeller pitch
254 mm
Actual boat speed
20 km/h
Theoretical boat speed
22.86 km/h
Propeller slip
12.51 %

Assumptions and limitations

  • This is the ideal screw advance per revolution with an empirical slip fraction. The ratio is engine rpm divided by propeller rpm. Positive forward speed and slip from zero up to but excluding one are supported.
  • Unit selectors convert known physical quantities. Leave a supported unknown blank; derived inverse branches are limited by the stated model and available captured equations.

Common questions

What does this calculation assume?

This is the ideal screw advance per revolution with an empirical slip fraction. The ratio is engine rpm divided by propeller rpm. Positive forward speed and slip from zero up to but excluding one are supported.

Can I solve for an input?

Where the captured model supplies an inverse, leave that quantity blank and enter the remaining known quantities. A positive square-root or principal trigonometric inverse may represent only one of multiple mathematical branches.

Which unit should I use for the worked example?

The example uses the initial metric unit selection beside each field. Change a unit using its selector to convert the same known quantity; switching a unit does not change the underlying physical value.

References

Captured local equations and controls are preserved with explicit physical-domain and exact-unit corrections where disclosed. Diagram explanations and guides are authored for Bookify. Validation covers the recorded cases and does not certify every real-world application. Bookify uses the exact relationship one revolution = 2π radians instead of the captured rounded angular-speed factor.

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