or d/L = 0.1547 ; 



therefore, the technique applies. Second, check that the wave has not 

 broken, or that H^/L <_ 0.143 tanh 2 ti d/L. in this problem: 



H/L = 5.0/77.56 <_ 0.143 (0.7497) 



0.0644 < 0.1072 ; 



therefore, the incident wave has not broken before reaching the structure. 



Using Figure 2 (curve 1) or Figure 4 the freeboard, (h - dg) , is 

 determined as 1.75 feet. 



************** EXAMPLE PROBLEM 2************** 



GIVEN : H = 5.0 feet, T = 4.5 seconds, and dg = 12.0 feet. 



FIND: The freeboard of a vertical breakwater which has a crest width 

 approximately equal to the water depth (B - dg) with Hj^ = 0.5 foot. 



SOLUTION : The d/L and H/L conditions of this problem fall into the 

 required ranges (see problem 1). From Figure 2 (curve 2) or Figure 5 

 the freeboard is determined as 4.3 feet. 



************** EXAMPLE PROBLEM 3************** 



GIVEN : H^ = 5.0 feet, T = 4.5 seconds, and dg = 12.0 feet. 



FIND: The transmitted wave height, H^ , of a vertical breakwater (B ~ dg) 

 with the crest height at the water level, (h - dg) = 0. 



SOLUTION : From Figures 2 (curve 2) and 5 the transmitted height is deter- 

 mined as 2.3 feet. 



************** EXAMPLE PROBLEM 4************** 

 GIVEN : The conditions in problem 2. 



FIND : The freeboard for a composite breakwater, (h - dg) , for d^/dg = 0.5 

 with Ht = 0.5 foot. 



SOLUTION : The d/L and H/L conditions of this problem fall into the 

 required ranges (see problem 1) . From Figure 2 (curve 4) or Figure 7 

 the (h - dg) = 5.3 feet. 



15 



