300 

 200 



100 



50 



20 



10 



GOODYEAR FTB 

 D/ d =0.15 % =14,21 



FROM CERC DATA 



5 10 



Wave Steepness, H/L (pet) 



Figure 88. Effect of relative wavelength, L/W, and wave steepness, H/L, 

 on force parameter, F/yW 2 , for two-dimensional prototype-scale 

 model of Goodyear Tire and Rubber Company scrap-tire floating 

 breakwater concept (after Harms, 1979a). 



e. Model-Scale Mooring Line Forces . The force parameter, F/yW 2 , has 

 some advantageous properties (it is a monotonically increasing function of 

 both L/W and H/L). This behavior is shown in Figure 89, where the curves 

 were generated by fixing the relative depth parameter, D/d, and the wave 

 steepness, H/L. The resulting design force curves are applicable for wave 

 steepness of 3 and 6 percent for the Goodyear Tire and Rubber Company break- 

 water concept, according to Harms and Bender (1978). 



f. Comparison of Prototype- and Model-Scale Mooring Line Forces. Harms 

 (1979a) compared the prototype-scale data by Giles and Sorensen (1978) to the 

 model-scale data of the same breakwater configuration by Harms and Bender 

 (1978). The data, plotted as the force parameter, F/yW 2 , versus the rela- 

 tive breakwater width, L/W, showed good agreement in Figure 90, surprisingly 

 so in view of the differences in elasticity of the mooring systems used in the 

 two studies. This circumstance was attributed to the great flexibility of the 

 breakwater system; i.e. , when attached to such a highly flexible structure as 

 a tire breakwater, even the most rigid mooring system cannot generate the peak 

 shock-load mooring forces associated with rigid structures. The influence of 

 wave steepness, H/L, is also apparent (Harms, 1979a), as doubling of the 

 wave steepness (from 4 to 8 percent at L/W = 0.8) causes a force parameter 

 increase of about 400 percent. 



135 



