The frequency of breaker observations approaching "normal" to the 

 shoreline, as defined by each of the three direction notations used is 

 listed in Table 2. During use of the compass sector method at' Boca Raton, 

 the breakers were recorded as approaching from the "east" sector 46 per- 

 cent of the time. When breaker direction was recorded to the nearest 

 degree, only 21 percent of the observations were reported as shore-normal 

 at Boca Raton. Large differences were noted between the frequency of 

 "shore-normal" observations using the 10° coastal sector 3 notation and 

 the frequency of observations within the 85° to 95° protractor method 

 sector. This suggests that when an observer detected a small angle from 

 a direct onshore breaker approach, either sector 2 or 4 was recorded when 

 using the coastal sector method. 



Table 2. "Normal" breaker approach frequency for visual methods. 





Dates in use 



"Normal" sector 



Method 



Name 



Size 



Reported frequency 





Jupiter 



Boca Raton 



Hollywood 



Compass sector 



Jan. 1969 to Sept. 1969 



East 



45° 



1 



0.46 



1 



Coastal sector 



Sept. 1969 to Aug. 1972 



3 



10° 



0.24 



0.27 



0.14 



Protractor 



Aug. 1972 to June 1973 



85° to 95° 



11° 



0.57 



0.42 



0.49 



Protractor 



Aug. 1972 to June 1973 



90° 



1° 



0.26 



0.21 



0.20 



No data. 



Observations which were made using the compass sector method, and 

 subsequently converted to the coastal sector notation, show a strong 

 bias toward sectors 1 and 5, a result of the relatively crude precision 

 of notation (see App. C, January through September 1969). Observations 

 subsequent to September 1969 suggest an observer bias influenced by the 

 abandoned compass sector method until September 1970, after which direc- 

 tion observations appear tmbiased. 



In comparing the three methods of determining breaker direction, it 

 is apparent that the compass sector method is the least useful for engi- 

 neering purposes. The coastal sector method tends to over- represent 

 breakers approaching from sectors 2 and 4, while the protractor method 

 may over- represent breakers approaching 90° (see coastal sector and 90° 

 protractor entries in Table 2) . The average annual directions for all 

 data were as follows: Jupiter, 87.1°; Boca Raton, 90.7°; and Hollywood, 

 90.4°. 



At Jupiter, the higher breakers generally came from the northeast and 

 prevailed during August through April. However, the highest breakers 

 (8 feet) were observed during storms coming directly onshore (two obser- 

 vations) or from the southeast (one observation) . Breakers from the 

 southeast were predominant during May through July. 



At Boca Raton, the higher breakers generally came from the southeast 

 and prevailed during April through September. The highest breakers came 



46 



