65 

 60 

 55 

 50 

 45 



t; 40 



cd 55 



o- 30 



^ 25 



20 



15 



10 



5 







20 



15 



u 

 z 



o- 



FREQUENCY HISTOGRAM: PERCENT TIME SUBMERGED PER 

 FOUR HOUR SUMMARY PERIOD 

 ALL PTTS 



PERIODS 1-4 COMBINED 

 § PERIODS = 294 

 X=78 SD=13 







5 







1 1 i \ \ i \ r 



23:16-05:15 GMT (1) X=75 SD=14 N = 85 

 05:16-11:15 GMT (2) X=78 SD=13 N = 86 

 11:16-17,15 GMT (3) X=79 SD=12 N=73 

 17:16-23 15 GMT (4) X = 80 SD=10 N = 50 



/ 



o 

 '^ 



I 



CD 

 CO 



in 

 I 



lo in CO CO ^- 

 PERCENT TIME SUBMERGED 



Figure 68. Frequency histogram of mean percent time submerged for all 6-hour summary 

 periods and all 1990 PTTs combined. Note: x = mean percent time submerged (seconds); 

 sd = standard deviation of the mean. 



106 



