Enter the waterline of the boat in feet while under motion into the calculator to determine the hull speed.

Hull Speed Formula

The following formula is used to calculate a hull speed:

HS = 1.35 * SQRT (WL)

  • Where HS is the hull speed (MPH)
  • WL is the water line (ft)

This formula is only an estimate. The true speed depends on the weight and shape of a hull as well.

What is hull speed?


Hull speed is a measure of the velocity of a sea fairing vessel with respect to its hull.

The hull speed is a factor of the waterline measured on the hull speed when the boat is traveling.

How to calculate hull speed?


The following example problem outlines the steps required to calculate the hull speed of a boat.

First, determine the waterline when the boat is under motion. In this example, the water line is measured to be 10 FT.

Next, the final and last step is to simply plug the waterline value into the formula above to calculate the hull speed:

HS = 1.35 * SQRT (WL)

HS = 1.35 * SQRT (10)

HS = 4.2609 MPH