Hull Speed Calculator
Estimate a displacement hull's theoretical max speed from waterline length using this free hull speed calculator, right in your browser.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the waterline length in metres.
- Read the hull speed.
How it works
Hull speed (knots) ≈ 1.34 × √(waterline length in feet).
Worked example
10 m waterline. ≈ 7.7 knots.
Common mistakes
- Using overall length — use the waterline length (LWL).
- Applying it to planing hulls, which can exceed hull speed.
Frequently asked questions
Can a boat go faster than hull speed?
Displacement hulls struggle to; planing and multihulls are designed to break past it.
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Cite this tool
Zerdly. (2026). Hull Speed Calculator. Retrieved from https://www.zerdly.com/tools/hull-speed-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.