Application 



Wave energy spectra for the largest recorded wave height event 

 are shown in Figure 12. For a known incident spectrum the transmitted 

 spectrum can be predicted using values of C^ from Figure 10. Using 

 the La Salle Park curve, this has been done for pressure transducers 3 

 and 5 in Figure 4; results are provided in Table 1. The predicted 

 transmitted characteristic wave height is 0.193 m while the value 

 calculated from the pressure measurements is 0.184 m, giving an 

 overprediction of 4.9 percent. 



A simpler approach to predicting the transmitted wave height 

 would be to use a single value of C^ corresponding to the peak 

 frequency. For the example in Table 1, fp = 0.36 Hz giving C^ = 

 0.355. The predicted transmitted wave height would be 0.638 x 0.355 = 

 0.226 m, giving an overprediction of 25 percent. In general, the 

 simpler approach will be less accurate than the spectral approach. 

 Whenever the incident spectrum is multi -peaked, only the spectral 

 prediction method should be used. 



For practical purposes, a breakwater is seldom required unless 

 wave attenuation of 50 percent or more is needed. From Figure 10 it can 

 be seen that to obtain C^- < 0.5 the ratio L/B must be less than 0.85. 

 Therefore, a rule of thumb for Goodyear FTB's would be that the beam 

 must be at least 1.2 times the design wavelength. For another type of 

 FTB, the Pipe-Tire floating breakwater (Harms et al . 1981), a comparable 



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