Scale was created by Admiral
Sir Francis Beaufort in 1805, his wind strength and sea state numbers
the forecasting terms still in use today.
Wind Speed Kts)
Wind Speed km/hour
0 / Calm
Sea like a mirror, Wave Height 0 ft.
1 / Light Air
Ripples but without foam crests Wave Height
> 0.25 ft.
2 / Light Breeze
6 – 12
Small wavelets. Crests have a glassy appearance and
do not break,
Wave Height: >0.5 ft
3 / Gentle Breeze
13 – 20
Large wavelets. Some whitecaps Wave Height
4 / Moderate Breeze
21 – 30
Small waves, Fairly frequent white caps, Wave
Height >4 ft.
5 / Fresh Breeze
31 – 40
Moderate waves, many white caps, Chance of some
spray, Wave Height
6 / Strong Breeze
41 - 50
Large waves begin to form; the white foam crests
are more extensive
everywhere. Probably some spray, Wave Height >10 ft.
7 / Near Gale
Sea heaps up and white foam from breaking waves
blown in streaks in
the direction of the wind. Wave Height >14 ft.
8 / Gale
Moderately high waves of greater length, Crests
begin to break into
spindrift, In the tropics categorized as a Tropical Storm, Wave
Height >18 ft.
9 / Strong Gale
High waves. Dense foam streaks along the direction
of the wind.
Crests of waves begin to topple and roll over. Spray may affect
visibility, Wave Height >23 ft.
10 / Storm
Very high waves with long overhanging crests. Foam
is blown in dense
white streaks, The surface of the sea takes on a white appearance.
The tumbling of the sea becomes heavy, Visibility affected. Wave
Height >29 ft.
11 / Violent Storm
Exceptionally high waves, The sea is completely
covered with long
white patches of foam lying along the direction of the wind, Wave
crests are blown into froth, Visibility, Wave Height >37 ft.
12 / Hurricane
The air is filled with foam and spray. Sea
completely white with
driving spray. Visibility very seriously affected. Equal to a
Category 1 Hurricane on the Saffir-Simpson Scale, Wave Height 45 ft.
Forecasting Terms used to
describe how the wind is forecast to behave.
This is always the direction from which wind is
Wind becoming cyclonic
A rapid change in direction, usually associated
with frontal system
Wind direction changing in a clockwise direction,
eg. S to SW to W
Wind direction changing in an anti-clockwise
direction, eg. E to NE
to N etc.
Forecasting Terms for Visibility.
Forecasting Terms are used to
describe viability quite specifically.
Down to less than 1000 Meters, 0.6 nautical miles.
Between 1000 Meters and 2 nautical miles
Between 2 and 5 nautical miles
More than 5 nautical miles
Expected within 6 hours of time of issue or
Expected within 6 to 12 hours of time of issue or
Expected more than 12 hours from time of issue or
Rising / Falling More Slowly.
The pressure is rising or falling at a slower rate
previous three hours.
Rising / Falling slowly.
A pressure change of 0.1 to 1.5 0 hPa/mb in the
Rising / Falling.
Pressure change of 1.6 to 3.5 0 hPa/mb in the
preceding three hours.
Rising / Falling quickly.
Pressure change of 3.6 to 6.0 0 hPa/mb in the
preceding three hours.
Rising / Falling V. Rapidly.
Pressure change of more than 6.0 hPa/mb in the
preceding three hours.
Now Rising / Falling.
Pressure has been Rising / Falling or steady in the
hours, but at the time of observation was definitely beginning to
Rise / Fall.
of pressure systems
These Forecasting Terms are used to describe the predicted
Moving at less than 15 Knots
Moving at 15 to 25 Knots
Moving at 25 to 35 Knots
Moving at 35 to 45 Knots
Moving at more than 45 Knots
“We clear the harbor and the wind catches her sails and my beautiful ship leans over ever so gracefully, and her elegant bow cuts cleanly into the increasing chop of the waves.
I take a deep breath and my chest expands and my heart starts thumping so strongly I fear the others might see it beat through the cloth of my jacket.
I face the wind and my lips peel back from my teeth in a grin of pure joy.” (L.A. Meyer)
is a brand new Social Network for Wooden Boat Enthusiasts.
A place where members can
comment, show off their Wooden Boats,
ask and answer Forum
questions, upload Photographs
and just get to know and chat with other Wooden Boaters.
I am perfectly aware that the majority of Wooden Boat aficionados are sensible folk. However, I need to point out that I am an amateur wooden boat enthusiast simply writing in order to try to help other amateur wooden boat enthusiasts. And while I take every care to ensure that the information in DIY Wood Boat.com is correct, anyone acting on the information on this website does so at their own risk.