6 

 U 



c 



•H 

 O 



o 

 s: 







i 



1 



1 



i 



1 ' 1 .«-.' 



w ' 

















1 







H\~ 





^' 





•3 



o 













dJP\ 



/ 



u 



h . - 



1 











// / / ////// 



/ / / / 



•2 





o 



9 















9 





9 



9 

 9 



9 



• peak 



9 









9 



9 





9 



9 



•1 













e 



1 





- 











e 



e 









Q 



average 













e 







e 





e 



05 



- 



i 



1 



1 



i 



i . i 



e 



i 



Figure 113. 



2-5 3 3-5 4 4-5 



Ratio of Wavelength-to-Half Structure Width, L/L, 



Effect of relative breakwater width, L/L , on average and peak 



mooring force parameter, Fh /yH?L, for four-cylinder A-frame 

 floating breakwater (after Ofuya, 1968). 



forces on the structures that the magnitude of the forces induced in the 

 mooring lines varied randomly with time. From a design standpoint, the peak 

 forces are of most interest; however, the average forces regarding hysteresis 

 of the mooring ropes, due to repeated loading, are also important. A strong 

 trend exists in the relationship between the mooring force parameter, 

 Fh /yH?L, and the relative breakwater width, L/L , although the scatter 

 is partly due to several factors (wave steepness, relative water depth, and 

 response characteristics of the moored breakwater to excitation). 



The A-frame floating breakwater investigations conducted by Western Canada 

 Hydraulic Laboratories Ltd. (1966a) and Ofuya (1968) indicate that an effec- 

 tive floating breakwater system can be developed which has the large moment of 

 inertia of mass as the dominant factor, rather than the mass itself. Wave 

 heights are reduced by the combined processes of wave reflection, dissipation, 

 and wave interference. The reflection and transmission coefficients are 

 influenced by incident wave steepness, and for the deepwater waves, the effect 

 of the vertical curtain depth on the transmission coefficient, CL, is small, 

 provided h /d is approximately 0.25. The scatter in the display of the 

 horizontal force parameter, Fh /yH?L, versus the relative breakwater width, 

 L/L , is due to the effect of wave steepness. 



165 



