Hull Speed

Hull Speed Calculator

Use the input box below to calculate the theoretical maximum hull speed in knots based on the length of the boat's waterline in feet.

Select length of waterline in feet:


As a typical sailboat with a displacement hull moves through the water, it creates a series of waves at the bow. The distance from the crest of one wave to the crest of the next is called the "wavelength".

Hull speed is the speed at which the wavelength of the boat's bow wave is equal to the boat length. As boat speed increases from rest, the wavelength of the bow wave increases, and usually its crest-to-trough height increases as well. When hull speed is reached, a boat in pure displacement mode will appear trapped in a trough behind its very large bow wave.