Boat Speed Calculator FAQ

How is a boat's speed calculated? uses a modified Savitsky method to calculate boat's resistance (R) and AEW propeller series data to calculate a propeller thrust (T). Calculator iterates over a range of speeds to find the final speed where R = T.

Can I use the calculator for waterjets? aims to keep the useability of the calculator as easy as possible with minimal inputs. For this reason the calculations are limited currently for outboards and sterndrives only. However waterjets and other propulsors might be added in the future.

Is cavitation taken into account? assumes a cavitation free condition, meaning that cavitation is not taken into account. While cavitation is a significant phenomenon, that can ruin the whole party, it is also extremely complex in nature and difficult to evaluate accurately.

Are mechanical losses taken into account in the driveline? accounts for typical mechanical losses in outboards and sterndrives

What to do when calculator returns an error?

Typical sources of error:

  • Boundary conditions might not be met - see Documentation
  • works only for planing conditions - try increasing the rpm to make sure the boat gets on step.