12. Volume of core per 100 m: 66,000 m"^ 



13. Weight of core stone: 0.00192 - 0.0575 metric tons 



(1.92 to 57.5 kg) 



3 



14. Volume of secondary cover layer per 100 m: 1271 m 



15. Thickness of secondary cover layer: 3.37 m 



16. Weight of secondary cover layer stone: 2.421 metric tons 



3. Diffraction Analysis; Diffraction Around Breakwater . 



For the purposes of this problem, establish the required breakwater length 

 so that the maximum wave height in the harbor is 1 meter when the incident 

 wave height is 6 meters (1 percent wave for Hg = 3.59 m ) and the period T = 

 7.78 s . Assume waves generated in Delaware Bay. 



DIRECTION OF WAVE APPROACH 



" BREAKWATER 



200m 

 B- 



= ? 



V = 1^ = 1.56 T^ = 1.56 (7.78)^ = 94.42 m 



Depth at breakwater d = 16.50 m 

 Depth in basin d = 31.74 m 



d_ ^ 31.74 

 L^ 94.42 



= 0.33817 



From Appendix C, Table C-1, 



Therefore, 



J- = 0.34506 



L = 91.98 m , say L = 92 m 



8-74 



