Estimate theoretical hull speed for displacement boats, sailboats, trawlers, canoes, kayaks, and cruising boats based on waterline length. This calculator also estimates cruising speed, speed-length ratio, trip time, distance covered, and how far above or below hull speed your entered speed is.
Waterline length:
The calculator uses the boat’s waterline length, not total overall length, because the wave pattern is based on the hull length touching the water.
Hull speed:
For many displacement boats, theoretical hull speed is estimated as 1.34 times the square root of waterline length in feet.
Trip planning:
The calculator also estimates efficient cruising speed, trip time, speed-length ratio, and whether an entered speed is below, near, or above hull speed.
A hull speed calculator helps estimate realistic speeds for sailboats, trawlers, displacement cruisers, canoes, kayaks, and other boats that do not normally plane.
Actual boat speed depends on hull shape, displacement, engine power, sail area, trim, load, propeller, sea state, current, wind, hull cleanliness, and whether the boat can plane or surf.
This calculator uses the standard displacement hull speed estimate:
Hull Speed = C × √LWL
Hull speed is a rough estimate of the speed where a displacement hull begins to require much more power to climb its own bow wave.
Use waterline length, often called LWL. Overall boat length can be longer than the part of the hull actually in the water.
Yes. Planing boats, surfing boats, some multihulls, and very light hulls can exceed the basic displacement hull speed estimate.
No. Cruising speed is often lower than hull speed because it is more efficient, quieter, safer, and easier on the boat and engine.