T p . sec 



H . ft Measured 



C t 



Incident 



Behind Reef 



Behind Breakwater 



7.0 



2.2 



0.8 



0.4 



0.18 



7.0 



4.0 



1.4 



0.6 



0.15 



7.0 



6.6 



2.4 



0.9 



0.14 



7.0 



9.6 



3.6 



1.2 



0.13 



7.0 



13.8 



4.9 



1.4 



0.10 



11.6 



1.9 



1.2 



0.6 



0.32 



11.6 



4.1 



2.1 



1.1 



0.27 



11.6 



6.5 



3.3 



1.6 



0.25 



11.6 



8.9 



4.6 



2.1 



0.24 



11.6 



11.4 



6.0 



2.5 



0.22 



11.6 



13.6 



7.3 



3.0 



0.22 



11.6 



17.5 



9.4 



4.1 



0.23 



11.6 



19.3 



10.5 



4.9 



0.25 



11.6 



20.9 



11.3 



5.5 



0.26 



As shown above, Plan 4A showed slightly improved transmission 

 performance, relative to Plan 4. The existing breakwater again was 

 completely stable (Photos 30 and 31). The reef experienced some damage 

 (Photo 32) with stone from the lakeward edge of the crown being displaced 

 downslope. 



Summary of results (Plans 2, 2A, 3, 4, and 4A) 



Figures 9, 10, and 11 present transmitted wave height as a function of 

 incident wave height for constant wave period. These data show that all plans 

 produced similar transmission results, with Plans 4 and 4A providing slightly 

 greater protection. Figure 12 presents wave heights behind the reef and these 

 data show that all plans (except Plan 2A) reduce 19-ft incident waves to 

 heights of about 13 ft or less. 



All plans except 2 A eliminated damage to the existing breakwater. The 

 5-ton stone was acceptable for all of the improvement structures; however, 

 Plan 4A experienced some damage with stone from the lakeward edge of the 

 crown being displaced downslope. 



Plans 2, 3, 4, and 4A varied such parameters as the volume of stone, 

 structure height, and crown width. However, all tests were conducted with a 

 150-ft spacing between the reef and the existing breakwater; therefore, it was 

 decided to test one additional plan (Plan 4A1) with this spacing reduced to 

 75 ft. Plan 4A1, shown in Photo 33, was identical to Plan 4A except for the 

 reduced spacing. Transmission test results were as follows: 



18 



Chapter 3 Tests and Results 



