The Beaufort Scale

As we head into the realms of open water canoeing, keeping an eye on the wind and it's effects on our environment are incredibly important. In order to assess the wind and it's impact on open water and sea conditions, the Beaufort Scale is used.

The table below gives a summary of the different scales and equivalent wind speeds. Often our weather forecasts on sites such as the BBC show wind speeds in Miles Per Hour. To convert knots to mph multiply it by 1.15 to give the Beaufort Scale in Miles Per Hour.

Specifications and equivalent speeds
Beaufort wind scale
Mean Wind Speed
Limits of wind speed
Wind descriptive terms
Probable wave height in metres*
Probable maximum wave height in metres*
Seastate
Sea descriptive terms
Knots
ms-1
Knots
ms-1
0 0 0 <1 <1 Calm - - 0 Calm (glassy)
1 2 1 1–3 1-2 Light air 0.1 0.1 1 Calm (rippled)
2 5 3 4–6 2-3 Light breeze 0.2 0.3 2 Smooth (wavelets)
3 9 5 7–10 4-5 Gentle breeze 0.6 1.0 3 Slight
4 13 7 11–16 6-8 Moderate breeze 1.0 1.5 3–4 Slight–Moderate
5 19 10 17–21 9-11 Fresh breeze 2.0 2.5 4 Moderate
6 24 12 22–27 11-14 Strong breeze 3.0 4.0 5 Rough
7 30 15 28–33 14-17 Near gale 4.0 5.5 5–6 Rough–Very rough
8 37 19 34–40 17-21 Gale 5.5 7.5 6–7 Very rough–High
9 44 23 41–47 21-24 Severe gale 7.0 10.0 7 High
10 52 27 48–55 25-28 Storm 9.0 12.5 8 Very High
11 60 31 56–63 29-32 Violent storm 11.5 16.0 8 Very High
12 - - 64+ 33+ Hurricane 14+ - 9 Phenomenal

*

  1. These values refer to well-developed wind waves of the open sea.
  2. The lag effect between the wind getting up and the sea increasing should be borne in mind.
  3. To convert knots to mph multiply by 1.15, for m/s multiply by 0.514.

Remember the impact of Fetch will have on the conditions. For example, working behind a sheltered reservoir dam wall in force 3 conditions could be quite calm. As you move further away from the obstacle the impact of the wind on the water increases causing larger waves.

Keep safe on the water!