| Beaufort Number / Wind speed |
Wind
Force |
Sea Surface |
Smack
Sail plan |
Near Coast |
Ships |
Sea
State |
Sea
Height
(m) |
Sea
Code
|
|
0
<1 Knot
|
Calm |
Calm |
|
Sea like mirror |
Calm |
0 |
0 |
Calm
|
1
1-3 kn
1-3 mph
1-5 kph |
Light
air |
Ripples with the appearance of scales;no
foam crests. |
|
Fishing smack just has steerage
way. |
Man-of-war with all sails set will
just have steerage way. |
0 |
0 |
Calm |
2
4-6kn
4-7mph
6-11kph |
Light
Breeze |
Small wavelets; crests of glassy
apprearance, not breaking. |
 |
Wind fills the sails of smacks
which then travel at about 1-2 knots. |
Man-of-war will sail at 1 to 2 knots. |
1 |
0
to
0.1 |
Calm,
rippled |
3
7-10kn
8-12mph
12-19kph |
Gentle Breeze |
Large wavelets; crests begin to
break; scattered whitecaps. |
|
Smacks begin to careen and travel
about 3-4 knots. |
Man-of-war will sail at 3 to 4 knots. |
2 |
0.1
to
0.5 |
Smooth |
4
11-16kn
13-18mph
20-28kph |
Moder
-ate
Breeze |
Small waves, becoming longer; numerous
whitecaps. |
 |
Good working breeze, smacks carry
all canvas with good list. |
Man-of-war sails clean and full
at about 5 to 6 knots. |
3 |
0.5
to
1.25 |
Slight |
5
17-21kn
19-24mph
29-38kph |
Fresh Breeze |
Moderate waves, taking longer form;
many whitecaps; some spray. |
 |
Smacks shorten sail. |
Man-of-war in chase will just carry
royals and courses. |
4 |
1.25
to
2.5 |
Moder-
ate |
6
22-27kn
25-31mph
39-49kph |
Strong Breeze |
Larger waves forming; whitecaps
everywhere; more spray. |
 |
Smacks have double reef in mainsail;
care required when fishing. |
Man-of-war will have single reefed topsails and
top-gallant sails. |
5 |
2.5
to
4 |
Rough |
7
28-33kn
32-38mph
50-61kph |
Near
Gale |
Sea heaps up; white foam from breaking
waves begins to blow in streaks. |
|
Smacks remain in harbour and those
at sea lie-to. |
Man-of-war will have double-reefed
topsails, jib and courses. |
6 |
4
to
6 |
Very
Rough |
8
34-40kn
39-46mph
62-74kph |
Gale |
Moderately high waves of greater
length; edges of crests begin to break into spindrift; foam is
blown into wellmarked streaks. |
 |
All smacks make for harbour, if
near. |
Man-of-war will have triple-reefed
topsails, jib and courses. |
6 |
4
to
6 |
Very
Rough |
9
41-47kn
47-54mph
75-88kph |
Strong
Gale |
High waves; seas begins to roll;
dense streaks of foam; spray may reduce visibility. |
|
- |
Man-of-war will have close-reefed
topsails and courses. |
6 |
4
to
6 |
Very
Rough |
10
48-55kn
55-63mph
89-102kph |
Storm |
Very high waves with overhanging
crests; sea takes white appearance as foam is blown in very dense
streaks; rolling is heavy and visibility is reduced. |
|
- |
Man-of-war will scarcely bear close-reefed
main-topsail and reefed foresail. |
7 |
6
to
9 |
High |
11
56-63kn
64-72mph
103-117kph |
Violent Storm |
Exceptionally high waves; sea covered
with white foam patches; visibility still more reduced. |
|
- |
Man-of-war will reduce sail to storm-staysails. |
8 |
9
to
14 |
Very
High |
12
>64kn
>73mph
>118kph |
Hurri-
cane |
Air filled with foam; sea completely
white with driving spray; visibility still more reduced. |
|
- |
Man-of-war will carry no sails. |
9 |
14 |
Pheno-
menal
|
