|
Force |
Speed (knots) |
Speed (kmh) |
State |
Wave Height (metres) |
At Sea |
Cuppa Scale |
Action of
Sailing Ship |
|
|
On Land |
|
0 |
0 |
0 |
Calm |
Nil |
Sea
like a mirror |
Cool
drink and snooze |
Makes
no headway |
|
|
Calm,
smoke rises vertically |
|
1 |
1-3 |
1-5 |
Light
air |
<0.1 |
Ripples
with the appearamce of cales are formed, but without foam
crest |
Another
cool drink, quiet read |
Just
has headway |
|
|
Smoke
drifts, wind vanes do not move |
|
2 |
4-6 |
6-11 |
Light
breeze |
0.1
- 0.3 |
Small
wavelets, still short but more pronounced; crests have a glassy appearance
and do not break |
Put
down glass to hold magazine page |
Wind
fills sails; makes up to 2 knots |
|
|
Wind
felt on face, vanes move, leaves rustle |
|
3 |
7-10 |
12-18 |
Gentle
breeze |
0.3
- 0.9 |
Large
wavelets, crests breaking, scattered whitecaps |
Keep
an eye on drink and put magazine down perhaps |
Heels
slightly under full canvas; makes up to 3 knots |
|
|
Leaves
and small twigs in constant motion, light flags flap |
|
4 |
11-16 |
19-30 |
Moderate
breeze |
0.9
- 1.5 |
Small
waves becoming longer, numerous whitecaps |
Drink
is slightly awkward, read chart |
Good
working breeze; under all sail; heels considerably |
|
|
Dust,
leaves, loose paper raised up, small branches move |
|
5 |
17-21 |
31-39 |
Fresh
breeze |
1.5
- 2.5 |
Moderate
waves of longer form, many whitecaps, spray |
Spill
remaining drink, hold chart firmly |
Shortens
sail |
|
|
Small
trees in leaf begin to sway, flags fully extended |
|
6 |
22-27 |
40-50 |
Strong
breeze |
2.5
- 4 |
Larger
waves, whitecaps everywhere, more spray |
Cup
of tea would be nice, sit on chart |
Double-reefs
mainsail |
|
|
Larger
branches of trees in motion, whistling heard in wires, umbrellas difficult
to use |
|
7 |
28-33 |
51-61 |
Moderate
gale |
4-
6 |
Sea
heaps up and white foam from breaking waves begins to be blown in streaks
along the direction of the wind |
Cup
slides in saucer, chart a little damp and stained |
Remains
in harbour, or if at sea, lies to. |
|
|
Whole
trees in motion, resistance felt when walking |
|
8 |
34-40 |
62-74 |
Fresh
gale |
6
- 8 |
Moderately
high waves of greater length; edges of crests begin to break into the
spindrift; the foam is blown in well marked streaks along the direction of
the wind |
Hot
tea in a mug then, if anyone’s making one |
Takes
shelter if possible |
|
|
Twigs
and small branches break off trees, progress generally
impeded |
|
9 |
41-47 |
75-87 |
Strong
gale |
8
- 10 |
High
waves; dense streaks of foam along the direction of the wind; crests of
waves begin to topple; tumble and roll over; spray may affect
visibility |
Mug
of hot tea would have been very nice…. |
- |
|
|
Slight
structural damage, slates blown off roofs |
|
10 |
48-55 |
88-100 |
Whole
gale |
10
- 12 |
Very
high waves with long overhanging crests; foam in great patches is blown in
dense white streaks along the direction of the wind; the surface of the
sea takes a white appearance, the tumbling of the sea becomes heavy
rolling sea; visibility affected |
Hard
to keep mug at lips, some may spill down chin on to remains of
chart |
- |
|
|
Trees
broken or uprooted, structural damage, boats break free from
moorings |
|
11 |
56-63 |
101-117 |
Storm |
12
- 16 |
Exceptionally
high waves (small and medium size ships might be for a time lost to view
behind the waves); the sea is completely covered with long white patches
of foam lying along the -direction of the wind; everywhere the edges of
the wave crests are blown into froth; very poor visibility |
Holding
mug properly now focuses one’s whole attention and chart hard to read
anyway |
- |
|
|
Wide
spread structural damage |
|
12 |
>64 |
>118 |
Hurricane |
>16 |
Air
filled with foam, sea completely white with driving spray; visibility very
seriously affected |
Tea
may be salty |
- |
|
|
Violence
and destruction. Massive and widespread damage to
structures. |
