TIME 



F = PEAK FORCE 



F = DRIFT FORCE, WHERE F I 1/lHj - F. ) 



F s = AVERAGE OF HIGHEST 1/3 PEAKS 



F r AVERAGE OF LOWEST 1/3 EXTREMES 



F„ S HIGHEST PEAK FORCE VALUE FOR LENGTH OF RECORD 



FROM REGION 1 



Figure 33. Definition sketch for force analysis. 



1978), the difference between F and this peak force is frequently small, but 

 on the other hand can be quite large as shown in Appendix B. In that appendix 

 the peak mooring force, F, is also compared to the significant peak force, 

 F g , for a large number of the tests. 



The cantilever force gage is calibrated at least once at the beginning and 

 ending of each day's testing; if zero drifts are observed, it is calibrated 

 more frequently. Calibration is accomplished manually via a separate cable 

 with mechanical load tightener and 2270-kilogram dial force gage in series, 

 attached close to the cantilever. A typical calibration record is shown in 

 Figure 25. The force values are always referenced to the static no-load 

 condition (i.e., with pully preload but no waves). 



V. EXPERIMENTAL RESULTS 



1 . Wave Transmission Data . 



For each breakwater configuration and water depth, the transmitted wave 

 height depends primarily on the width of the structure and the incident wave- 

 length (or period) and wave height. Dimensional analysis and physical insight 

 were invoked in Section IV to arrive at dimensionless parameters that would 

 describe the problem more succinctly and clearly and would also guide the 

 experimental effort and analysis of the results. This evolved in the presen- 

 tation of the data in the format shown in Figure 34. The wave height trans- 

 mission ratio, C t = IL^/H, is presented as a function of relative wavelength 

 L/B, with different symbols designating ranges of wave steepness H/L. These 

 are the primary parameters. The secondary parameters are listed in the insert 

 of each figure. These parameters specify the water depth (relative depth, 



37 



