Beaufort Scale for Wind Speed

Beaufort numbers are referred to as Force numbers. i.e. Beaufort number 7 is the same as Force 7 is 28 - 33 knots.
Force Wind
Description
Speed
Knots
Speed
Km/h
Land Water
0 Calm 0 1 0 1 Smoke rises
vertically
Water is like a mirror. Cannot sail.
1 Light Air 1 3 1 5 Smoke indicates direction. Not enough wind for vanes Small ripples on water. Enough wind for a light Spinnaker
2 Light Breeze 4 6 6 11 Wind felt on face. Tree leaves start moving. Vanes now indicate direction. Small wavelets. Wind now fills sail.
3 Gentle Breeze 7 10 12 19 Small flags are extended. Leaves move constantly. Large wavelets. Sailboats start to heel.
4 Moderate Breeze 11 16 20 28 Dust is raised by wind. Small branches start bending. Good working breeze. Saiboats at hull speed, full sail.
5 Fresh Breeze 17 21 29 38 Small trees are reacting to wind. Numerous whitecaps. Time to shorten sails.
6 Strong Breeze 22 27 39 49 Wind now whistles. Most branches in trees moving. Whitecaps eveywhere. Sailboats start to head ashore.
7 Near Gale 28 33 50 61 Whole trees now move. Much bigger waves. Sailboats remain at harbour.
8 Gale 34 40 62 74 Small branches are starting to break. Walking in now hard. Foam in well marked streaks. All boats now head in.
9 Strong Gale 41 47 75 88 Buildings are starting to show small damage. Low visibility due to spray.
10 Storm 48 55 89 102 Dangerous Situation High seas over 8 metres
11 Violent Storm 56 63 103 117 Dangerous situation High seas over 10 metres
12 Hurricane 63 up 117 up Dangerous situation High seas over 14 metres
"If one does not know to which port one is sailing, no wind is favorable." - Seneca
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