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Cruising information, articles, sources & resources for the UK sailing community
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Cruising information, articles, sources & resources for the UK sailing community
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| The Beaufort Scale for use at sea | |||||
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| knots | km/h | mph | |||
| 0 | Calm | Sea like a mirror | Less than 1 | Less than 1 |
Less than 1 |
| 1 | Very Light | Ripples with appearance of scales, no foam crests | 1 - 3 | 1 - 5 | 1 - 3 |
| 2 | Light breeze | Wavelets, small but pronounced. Crests with glassy appearance, but do not break. | 4 -6 | 6 - 11 | 4 -7 |
| 3 | Gentle breeze | Large wavelets, crests begin to break. Glassy looking foam, occasional white horses. | 7 - 10 | 12 - 19 | 8 - 12 |
| 4 | Moderate breeze | Small waves becoming longer, frequent white horses. | 11 - 16 | 20 - 29 | 13 - 18 |
| 5 | Fresh breeze | Moderate waves of pronounced long form. Many white horses, some spray. | 17 - 21 | 30 - 39 | 19 - 24 |
| 6 | Strong breeze | Some large waves, extensive white foam crests, some spray. | 22 - 27 | 40 - 50 | 25 - 31 |
| 7 | Near gale | Sea heaped up, white foam from breaking waves blowing in streaks with the wind. | 28 - 33 | 51 - 61 | 32 - 38 |
| 8 | Gale | Moderately high and long waves. Crests break into spin drift, blowing foam in well marked streaks. | 34 - 40 | 62 - 74 | 39 - 46 |
| 9 | Strong gale | High waves, dense foam streaks in wind, wave crests topple, tumble and roll over. Spray reduces visibility. | 41 - 47 | 75 - 87 | 47 - 54 |
| 10 | Storm | Very high waves with long overhanging crests. Dense blowing foam, sea surface appears white. Heavy tumbling of sea, shock-like, poor visibility. | 48 - 55 | 88 - 101 | 55 - 63 |
| 11 | Violent storm | Exceptionally high waves, sometimes concealing small and medium sized ships. Sea completely covered with long white patches of foam. Edges of wave crests blown into froth . Poor visibility. | 56 - 63 | 102 - 117 | 64 - 73 |
| 12 | Hurricane | Air filled with foam and spray, sea white with driving spray, poor visibility. | >64 | >119 | >74 |