those of 3 ft. height category waves by about 2$ percent. However, the 

 combined durations of the occasions when waves are> 6 feet never can 

 exceed the combined durations of wave s^ 3 feet. These facts are readily 

 seen in the smoothed wave profile shown in Figure 1. 



The various interpretations of the persistence curves can be made 

 by consulting the legend. As an example, suppose one is interested in 

 knowing how many times during the summer at Portland Lightship waves 

 will be less than 6 feet high continuously for at least 5 days (120 

 hours). Reference to the appropriate set of curves in Figure 3A shows 

 this to be about 10 percent of J48 (Point A), or about 5 times during the 

 season. Similarly, suppose one wants to know how many times during the 

 winter at Portland Lightship waves will exceed 6 feet for at least 2k 

 hours. Again, reference to the appropriate set of curves in Figure 3A 

 shows this to be about 13 percent of 1|3 (Point B), or $.6 times, i.e., 

 between 5 or 6 times during the season. 



Reference to the examples on the legend will suggest other ways in 

 which the curves can be 'used. Certain generalizations as to the seasonal 

 variability of waves at the lightships and ocean station vessels also are 

 evident from comparative studies. To illustrate, the durations of favorable 

 waves generally are longer than those of unfavorable waves, particularly 

 in summer. 



The bar graphs associated with each persistence graph give the total 

 relative frequencies of occurrence seasonally for each wave height category. 



