FIGURE I-1 Wind and sea scale for fully arisen sea.a

 

 

Wave Height-Feet

Wind Speed (knots)

Average

Significant Average 1/3 Highest

Average 1/10 Highest

Average Period

Average Wave Length

Minimum Fetch (nautical miles)

Minimum Duration (hours)

Average Wave Heightb (maximum)

0

0

0

0

-

-

-

-

-

2

0.05

0.08

0.10

0.5

10 in

5

18 min

 

5

0.18

0.29

0.37

1.4

6.7 ft

8

39 min

 

8.5

0.6

1.0

1.2

2.4

20

9.8

1.7 hrs

2(3)

10

0.88

1.4

1.8

2.9

27

10

2.4

13.5

1.8

2.9

3.7

3.9

52

24

4.8

31/2(5)

16

2.9

4.6

5.8

4.6

71

40

6.6

18

3.8

6.1

7.8

5.1

90

55

8.3

6(81/2)

19

4.3

6.9

8.7

5.4

99

65

9.2

20

5.0

8.0

10

5.7

111

75

10

22

6.4

10

13

6.3

134

100

12

91/2(13)

24.5

8.2

13

17

7.0

164

140

15

26

9.6

15

20

7.4

188

180

17

28

11

18

23

7.9

212

230

20

131/2(19)

30.5

14

23

29

8.7

258

290

24

32

16

26

33

9.1

285

340

27

34

19

30

38

9.7

322

420

30

18(25)

37

23

37

46.7

10.5

376

530

37

40

28

45

58

11.4

444

710

42

42

31

50

64

12.0

492

830

47

23(32)

44

36

58

73

12.5

534

960

52

46

40

64

81

13.1

590

1110

57

48

44

71

90

13.8

650

1250

63

29(41)

50

49

78

99

14.3

700

1420

69

51.5

52

83

106

14.7

736

1560

73

54

59

95

121

15.4

810

1800

81

56

64

103

130

16.3

910

2100

88

37(52)

59.5

73

116

148

17.0

985

2500

101

>64

>80

>128

>164

18

˜

˜

˜

45(-)

a To attain a fully arisen sea for a certain wind speed, the wind must blow at that speed over a minimum distance (fetch) for a minimum time (duration). When winds are 50 knots or more, the required fetch and duration for a fully arisen sea rarely occur. The wave heights shown in the last column, ''Average Wave Height'' represent what will be found on the average at given wind speeds.

Wave heights refer only to wind waves, and swells from distant or old storms are nearly always superimposed on the wind-wave pattern.

Practical Methods of Observing and Forecasting Ocean Waves, Pierson, Newuman, James, H.O. Pub. 603, 1955.

b H.O. 118A



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