FORCE 

 TRANSDUCER 



WATER 

 LEVEL 



-CONTROLS 



ALUMINUM ANCHORING GRID 



Figure 195. Experimental facility for evaluating the Bowley wave bar- 

 rier concept of floating breakwater (after Bowley, 1974). 



Input Wave Height = 1.0 in 



0.5 1.0 L5 2.0 2.5 3.0 3.5 

 Ratio of Wavelength-to-Water Depth, L/d 



Figure 196. Effect of number of modules, and relative water depth, 

 L/d, on transmission coefficient, CL, for Bowley wave 

 barrier concept of floating breakwater (after Bowley, 

 1974). 



The degree of sensitivity for the module, and ultimately the system, to 

 changes in the pitching mode period is shown in Figure 197. This effect is 

 accomplished by simply changing the length of the lines supporting the coun- 

 terweights. Increasing the length of these lines increases the period of the 

 module, allowing it to pitch significantly out of phase with the input waves. 

 A wide variation in the degree of this effect can be attained; Figure 197 is 

 the result of two particular counterweight locations with respect to the 

 center of buoyancy. The module acts as a pendulum, pitching about an axis, 

 and is thus amenable to simple pendulum adjustments. The scale effects of a 

 larger module were investigated, but were not readily apparent, as evidenced 

 in Figure 198. The results of a random sea input of the Pierson-Moskowitz 

 type are shown in Figure 199. A comparison of the input energy density versus 

 the transmitted energy density reveals that the wave barrier is quite capable 

 of spreading a sharp-peaked energy spectrum over a large frequency band. 



255 



