Welcome to the Prop Slip Calculator!
Propeller slip is a measure of efficiency and represents the difference between the theoretical speed you should achieve with a given prop, to the actual speed you are getting.ย Understanding the prop slip percentage can give you insights on boat and engine setup, and a means of comparing different propellers.
Follow these easy steps to determine your prop slip percentage.
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Always prioritize safety and follow local boating regulations.
Step 1: Select Your Units
The prop slip calculator will accept GPS speed in MPH or KPH.ย If you would like to work out your prop slip using MPH, select Imperial.ย For KPH, select Metric.
Step 2: Input Propeller Pitch
Most propellers have this stamped on them, otherwise this information can usually be obtained from the manufacturer.ย The calculator expects prop pitch in inches, so convert any metric units as required before populating this field.
Step 3: Input Gear Ratio
The gear ratio of your engine can usually be found in the manufacturer’s documentation.ย This is an important parameter and should be as accurate as possible.
Step 4: Input RPM
Input the engine RPM achieved at maximum boat/GPS Speed.
Step 5: Input GPS Speed
Input the maximum GPS Speed achieved during on-water testing.ย It is not recommended to use boat speed other than GPS, as these are much less reliable.
Step 6: Calculate Prop Slip
Click on โCalculate Prop Slipโ.ย This will tell you the percentage of slip your current setup is producing.
Additional tips:
You can also use this calculator to estimate whether you will need to change your propeller after flashing your ECU.ย Use our Boat Speed Calculator to estimate your new top speed after flashing your ECU, and enter these details, along with your current prop slip percentage, and calculate the new engine RPM.ย If this is above the engine rev limit, then try increasing the prop pitch until the desired maximum engine speed is reached.
This version allows users to calculate the propeller slip percentage based on prop pitch, gear ratio, max engine speed, and max GPS boat speed.
Disclaimer:
The Prop Slip Calculator provides an estimate based on your inputs and is provided as a tool to aid in boat and propeller setup.ย It in no way guarantees results.
