Hull Speed Calculator
Calculate theoretical maximum hull speed for displacement boats from waterline length.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
Hull Speed Calculator
Formula: Hull Speed = 1.34 × √LWL (feet)
Hull Speed (knots)
7.34 kn
Speed (km/h)
13.59 km/h
This tool provides general sports and fitness estimates for educational purposes only. It is not medical advice — consult a physician before starting or intensifying training, especially if you have a cardiovascular condition.
About the Hull Speed Calculator
The hull speed calculator estimates the theoretical maximum speed of a displacement hull: hull speed (knots) ≈ 1.34 × √(waterline length in feet). At this speed the boat’s bow wave matches its length, and going faster requires a large increase in power. Planing hulls can exceed it.
How to use it
- 1Enter the waterline length.
- 2Choose feet or metres.
- 3Read the hull speed in knots and km/h.
Worked example
a sailboat with a 30 ft waterline has a hull speed of about 1.34 × √30 ≈ 7.3 knots (13.6 km/h).
Common use cases
- Comparing sailboats
- Planning passage times
- Choosing engine power
Frequently asked questions
A:The theoretical maximum speed of a displacement hull, where the bow wave equals waterline length.
Reviewed for accuracy · Last updated October 7, 2026
Formulas follow published sports-science literature and official league definitions (Karvonen heart rate reserve, Cooper and Bruce protocols, MET compendium values, and standard baseball, cricket, and basketball statistics).
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources