22 



WAVE DIMENSIONS 



The. wave heights listed in table 8 mark the North Indian Ocean 

 during the season of the Northeast Monsoon as the quietest extensive 

 region, the waves there being less than 4 feet high for more than 

 four-fifths of the time, less than 7 feet high nearly 95 percent of the 

 time, very rarely as much as 12 feet high, and pract ically never so much 

 as 20 feet high. The equatorial belts of the eastern Pacific and of the 

 Atlantic oceans are the next quietest, with waves less than 4 feet 

 high for two-thirds of the time and one-half of the time respectively; 

 less than 7 feet high for four-fifths and three-fourths of the time, 

 more than 12 feet for only some 10 percent of the time, and rarely as 

 high as 20 feet. The waves, too, are at least no higher than 4 feet for 

 nearly one-half the time, even in the West Wind Belts of the Northern 

 Hemisphere, whether Atlantic or Pacific, with waves less than 7 feet 

 high for nearly two-thirds of the time; they are* less than 4 feet high 

 for roughly one-third to one-fourth of the time, and less than 7 feet 

 high for roughly one-half of the time, in the West Wind Belt of the 

 Southern Hemisphere, whether Indian or Pacific, though this is the 

 most turbulent part of the ocean. 



The relative frequency with which waves of different heights have 

 been observed at South Beach, Martha's Vineyard (table 9) with the 

 corresponding tabulation of the height of the surf for points on Long 

 Island, in New Jersey, and in North Carolina (see table 34, p. 151), il- 

 lustrates the great preponderance of the smaller waves (less than 5 

 feet high) along the middle Atlantic coast of the United States. 



Table 9. — Frequency distribution of waves of different heights at South Beach, 

 Marthas Vineyard, from observations made between November 1948 and April 

 1944- Each case is the mean of 20 consecutive waves 



The vast majority of waves, in short, are considerably lower than 

 12 to 15 feet, and waves much higher than 20 to 25 feet are not usual 

 anywhere. Thus the highest measured wave observed on the cruise 

 of the French frigate Venus around the world in 1836 to 1839 was 

 about 25 feet, in a case where 2 waves had joined, and otherwise only 

 about 23 feet; these were in the vicinity of Cape Horn. (So far as 



