Force 5: Fresh breeze
Wind: 17-21 kts | Sea: Moderate waves
| Force | Desc | Knots | Sea |
|---|---|---|---|
| 0 | Calm | < 1 | Flat |
| 1 | Light air | 1-3 | Ripples |
| 2 | Light breeze | 4-6 | Small wavelets |
| 3 | Gentle breeze | 7-10 | Large wavelets |
| 4 | Moderate breeze | 11-16 | Small waves |
| 5 | Fresh breeze | 17-21 | Moderate waves |
| 6 | Strong breeze | 22-27 | Large waves |
| 7 | Near gale | 28-33 | Sea heaps up |
| 8 | Gale | 34-40 | Moderately high |
| 9 | Strong gale | 41-47 | High waves |
| 10 | Storm | 48-55 | Very high |
| 11 | Violent storm | 56-63 | Exceptionally high |
| 12 | Hurricane | 64+ | Huge waves |
About Beaufort
What this tool does
Marine tools calculate hull speed, fuel burn rate at various RPMs, anchor rode length, displacement, sail area, tide times, and sea distances between ports.
Why use this tool
Boating safety depends on correct calculations. Not enough anchor rode in a squall means dragging anchor. Underestimating fuel burn means running dry offshore. These tools help you plan passages with proper safety margins.
How it works
Hull speed uses the formula 1.34 x sqrt(waterline length in feet). Anchor rode applies the 7:1 scope ratio for moderate conditions. Fuel burn estimates interpolate from engine RPM and consumption curves.
Pro tip
In heavy weather, increase your anchor scope to 10:1 or more. The holding power of an anchor depends almost entirely on the angle of pull, and more rode keeps that angle close to horizontal.
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