V. CONCLUSIONS 



Results for the predicted transmission coefficients were in good 

 agreement with laboratory and field data, and they showed how the in- 

 fluence of fixed-body transmission, and of sway, heave, and roll motions 

 on the transmission coefficient changed with increasing values of the 

 beam to wavelength ratio. 



The curves predicting the mooring line forces as a function of the 

 beam to wavelength ratio (or of incident wave frequency) followed those 

 for the measured responses. Care must be exercised in the analysis of 

 mooring line forces because there is strong evidence of nonlinear be- 

 havior. 



An extreme storm event did not occur during the sampling season at 

 Friday Harbor, nor during two winter sampling periods on the Alaskan 

 breakwaters; however, the anchor forces measured were about an order of 

 magnitude less than anticipated. 



The barges tied to the long leg of the breakwater did not noticeably 

 affect the transmission coefficients above a frequency of about 0.3 

 hertz, since the curves for all incident directions were approximately 

 coincident above that mean frequency. Below the frequency of 0.3 hertz, 

 it appears that the barges may have reduced the transmitted energy 

 somewhat. 



The extension of the theoretical model to include second-order terms 

 showed the presence of additional exciting-force terms at zero frequency 

 and at the difference frequency of the incident waves. Additional work 

 on the basic theoretical model is needed to incorporate these terms into 

 the calculations for mooring forces . The most appropriate means of veri- 

 fying the role of the second-order terras may be in a model basin, where 

 breakwaters of simple cross section and incident wave spectra having 

 only two or three components could be employed under controlled condi- 

 tions. 



71 



