RC Boat Speed Calculator
What this calculator does
Boat speed depends heavily on prop slip, hull style, water conditions, prop lift, and whether the motor or engine can hold the entered RPM under load. This calculator gives a practical estimate that helps compare props, motors, cell counts, and hull assumptions before testing on the water. Enter the motor Kv and cell count for a brushless estimate, or use loaded RPM for a gas or nitro estimate, then select the closest prop and hull type. Example: if two props show a similar estimated speed but one requires much more diameter or pitch, the conservative prop may be safer for the first run. Use the result with temperature checks, GPS speed, and data logs whenever possible.
In practical terms: It estimates RC boat speed from prop pitch, loaded RPM assumptions, and hull slip so setups can be compared quickly.
How to use it
Enter the electric or gas inputs, choose the prop and hull style, then compare estimated speed and setup range across different prop choices.
Example calculation
Use it to compare an X440 style prop against a higher pitch prop before deciding which one to test first.
FAQ
Why is RC boat speed only an estimate?
Prop slip, hull lift, water conditions, surface finish, balance, and actual loaded RPM all affect real speed. The calculator is best for comparing setups.
What is prop slip?
Prop slip is the difference between theoretical pitch speed and the distance the boat actually travels. Boats always have some slip in real water.
Should I enter unloaded or loaded RPM?
Use loaded RPM whenever possible. Unloaded RPM can make the speed estimate look much higher than what the boat can actually run.
How do I use this with the FE Boat Calculator?
Use this page for quick speed checks, then use the FE Boat Calculator when you need current, wattage, battery load, and ESC risk estimates.