The breaker depth for the given design wave is first determined. 

 With 



K 



— - = 0.0024 , 

 calculate, 



K K 



= 27r ^ = 6.28(0.0024) - 0.015 . 



Enter Figure 7-3 with H^/gT^ = 0.0024, using the curve for the given 

 slope of m = 0.050 (1:20), and find 



— ;- = 1.46. 



h' 



Therefore, 

 Calculate, 



H^ = 1.46(5) = 7.30 ft 



H. 



7.30 



= 0.00354 . 



gT^ 32.2 (8)2 

 Then, from Figure 7-2, from the curve for m = 0.05, 



— = 0.95 , 



and 



dy = 0.95 Hy = 0.95 (7.30) = 6.94 . 



Therefore, the wave will break a distance (6.94-4.0) /O. 05 = 58.8 ft. 

 in front of the structure toe. 



The runup value calculated above is a first approximation to the 

 actual runup, and is used to calculate a hypothetical slope that is 

 used to determine the second approximation to the runup. The hypo- 

 thetical slope is taken from the point of maximum runup on the 

 structure to the bottom at the breaker location (the upper dotted 

 line on Figure 7-22). Then, 



Ax = 58.8' 4- 30' + 20' + 30.3' = 139.1 ft , 

 and, the change in elevation is 



Ay = 6.94 + 16.1 = 23.04 ft , 

 and therefore 



Ax (139.1) 



cot = = « 6.0 . 



Ay (23.04) 



7-36 



