sea state

Code Hydrographic World Meteorological Organization
Term Height of waves,
feet
Description Significant Wave Height
meters (feet)
Range Mean
0 calm   Calm (glassy) 0 0
1 smooth <1 Calm (rippled) 0-0.1 (0-1) 0.05
2 slight 1-3 Smooth (mini-waves) 0.1-0.5 (1-2) 0.3
3 moderate 3-5 Slight 0.5-1.25 (2-4) 0.875
4 rough 5-8 Moderate 1.25-2.5 (4-8) 1.875
5 very rough 8-12 Rough 2.5-4.0 (8-13) 3.25
6 high 12-20 Very rough 4.0-6.0 (13-20) 5.0
7 very high 20-40 High 6.0-9.0 (20-30) 7.5
8 mountainous 40+ Very high 9.0-14.0 (30-45) 11.5
9 confused   Phenomenal >14.0 (45+) >14.0

 

Pierson-Moskowitz Sea Spectrum
Wind
Speed
(knots)
Sea
State
Significant
Wave
(feet)
Significant
Range of
Periods
(sec)
Average
Period
(sec)
Average
Length of
Waves
(feet)
3 0 <.5 <.5 - 1 0.5 1.5
4 0 <.5 .5 - 1 1 2
5 1 0.5 1 - 2.5 1.5 9.5
7 1 1 1 - 3.5 2 13
8 1 1 1 - 4 2 16
9 2 1.5 1.5 - 4 2.5 20
10 2 2 1.5 - 5 3 26
11 2.5 2.5 1.5 - 5.5 3 33
13 2.5 3 2 - 6 3.5 39.5
14 3 3.5 2 - 6.5 3.5 46
15 3 4 2 - 7 4 52.5
16 3.5 4.5 2.5 - 7 4 59
17 3.5 5 2.5 - 7.5 4.5 65.5
18 4 6 2.5 - 8.5 5 79
19 4 7 3 - 9 5 92
20 4 7.5 3 - 9.5 5.5 99
21 5 8 3 - 10 5.5 105
22 5 9 3.5 - 10.5 6 118
23 5 10 3.5 - 11 6 131.5
25 5 12 4 - 12 7 157.5
27 6 14 4 - 13 7.5 184
29 6 16 4.5 - 13.5 8 210
31 6 18 4.5 - 14.5 8.5 236.5
33 6 20 5 - 15.5 9 262.5
37 7 25 5.5 - 17 10 328.5
40 7 30 6 - 19 11 394
43 7 35 6.5 - 21 12 460
46 7 40 7 - 22 12.5 525.5
49 8 45 7.5 - 23 13 591
52 8 50 7.5 - 24 14 566
54 8 55 8 - 25.5 14.5 722.5
57 8 60 8.5 - 26.5 15 788
61 9 70 9 - 28.5 16.5 920
65 9 80 10 - 30.5 17.5 1099
69 9 90 10.5 - 32.5 18.5 1182

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