Hey guy's,
What is the formula used to calculate speed (MPH) and prop slip?
Printable View
Hey guy's,
What is the formula used to calculate speed (MPH) and prop slip?
Try this sihttp://www.go-fast.com/BOAT_SPEED_PREDICTIONS.HTM
Cannot calculate slip. Way too msny variables. Need to calculate the speed then measure it with a GPS. The difference will be the slip. Once you know the slip you can accurately calculate speeds with different props, RPM etc.
Formula is this:
1. Take RPM and divide by gear ratio.
2. Take result from #1 and multiply by propellor pitch.
3. Take result from #2 and divide by 5,280 then again by 12.
4. Multiply result from #3 by 60.
5. Multiply result from #4 by .9 for 10% slippage.
http://free.***boat.net/ubb/cool.gif
Thats good stuff Dreamin, But for accuracy, be sure to remember to call a 32p prop a 31p because of it being a 4 blade or a 28p is really a 27p, etc...