Sailing performance guide
Hull speed explained
Hull speed is a useful waterline-length benchmark for displacement boats—not a hard speed limit.
Hull speed (kn) ≈ 1.34 × √waterline length (ft)
What it measures
As a displacement hull accelerates, the bow and stern wave system lengthens. The traditional formula estimates the speed where the wavelength is roughly equal to the boat's waterline length.
How to interpret it
A longer waterline raises the benchmark. Hull form, displacement, power, sea state, and whether the boat can plane or surf all affect real speed, so the value works best as a comparison aid.
Apply it to a real design
Calculate these metrics for a sailboat, then compare the result with catalog models.
Open the calculator