RYA Information

http://www.rya.org.uk/regions/eastern/Pages/default.aspx

 

Measuring the wind – The Beaufort Scale

In 1805, a British Naval officer called Francis Beaufort introduced a scale from 0 -12 for measuring the speed of the wind at sea. Admiral Beaufort developed the scale based on his observations of the wind and waves and used everyday terms for each level of his scale.

The Beaufort Scale is still used today to describe the speed of wind at sea and the effect of wind on the surface of the water. Wind speed is measured in knots, with one knot equal to one nautical mile per hour. A nautical mile is just a bit longer than a land mile.

Today we also use wind instruments to measure the exact speed of the wind.

So lets’ take a look at the Beaufort Scale – the force, the speed of the wind in knots, how you would describe the wind and how you would describe the state of the sea…

Force Knots Description Sea Description
0 1 knot Calm Calm (glassy)
1 1 – 3 knots Light air Calm (rippled)
2 4 – 6 knots Light breeze Smooth (wavelets)
3 7 – 10 knots Gentle breeze Slight
4 11 – 16 knots Moderate breeze Slight – Moderate
5 17 – 21 knots Fresh breeze Moderate
6 22 – 27 knots Strong breeze Rough
7 28 – 33 knots Near gale Rough – Very Rough
8 34 – 40 knots Gale Very rough – High
9 41 – 47 knots Severe gale High
10 48 – 55 knots Storm Very High
11 56 – 63 knots Violent storm Very High
12 Over 64 knots Hurricane Phenomenal