0.80 



0.70 



■3 0.60 



0.50 



0.40 



0.30 



0.20 



3.5 



3.0 



2.5 



Wave Period, T (s) 



Figure 26. Summary of three-dimensional experimental study of single- 

 pontoon floating breakwater investigation, East Bay Marina, 

 Olympia Harbor, Washington (averages of gages 2, 3, 6, 7, 8, 

 11, and 12) (after U.S. Array Engineer District, Seattle, 1979). 



plans, (c) develop additional plans as necessary for the alleviation of unde- 

 sirable wave conditions, and (d) determine if modifications of the proposed 

 breakwaters could be designed to reduce construction costs significantly and 

 still provide wave protection. 



For this study, it was specified that for an improvement plan to be 

 acceptable, maximum wave heights in the Seabrook Lock entrance should not 

 exceed 2.0 feet. However, it was desired, if possible, that maximum wave 

 heights in the lock entrance not exceed 1.0 foot. To achieve the established 

 wave height criterion at the lock entrance with floating structures (providing 

 50 percent attenuation for waves approaching from a direction perpendicular to 

 the structure), Bottin and Turner (1980) determined that a total breakwater 

 length of 5,088 feet is required, consisting of two outer and three inner 

 breakwaters (Fig. 27). The typical wave pattern for a 3-second, 4.0-foot wave 

 is shown in Figure 28. 



59 



