Sailing Hull Speed Calculator
Enter the waterline length in feet to get the hull speed.
Result
How to use
- Enter your values in the fields above.
- Press Calculate to see your result instantly.
- Use the Share button to copy a link to your result.
About this calculator
Hull speed is the theoretical speed at which a traditional displacement-hull boat's own bow and stern wave crests match its waterline length, creating a wave "trough" the hull sits in and making it disproportionately hard to go faster without extra power or lifting out of the water; the widely used rule of thumb is 1.34 × √(LWL in feet) knots.
Naval architects and sailors use it as a quick ballpark for how fast a given monohull sailboat can realistically cruise under displacement conditions — a boat with a 25-foot waterline tops out around 6.7 knots — though modern planing hulls, catamarans and boats that surf down waves can and do exceed it.
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