b. Mooring Line Forces . In the Wave-Guard tests, a mooring line with a 

 three-tire mooring damper was installed. This allowed the mooring connection 

 at the breakwater end to be made directly to the massive beams, as opposed to 

 the more flexible but weaker tire connections, without incurring excessively 

 high peak mooring loads. Harms and Bender (1978) recommended that such moor- 

 ing dampers should also be installed in prototype structures. Since full- 

 scale tires are stiffer than the one-eighth scale-model tires tested, it was 

 recommended that at least five tires be used in the full-scale mooring damper. 

 Structural failures of scrap-tire floating breakwaters often occur because of 

 stress concentrations near the mooring connection. 



Design curves of the mooring force parameter, F/yW 2 , were developed for 

 the Wave-Guard and compared to the corresponding curves of the Goodyear Tire 

 and Rubber Company concept. Because of the greater wave attenuation capacity 

 of the Wave-Guard, a larger amount of wave energy is dissipated by this struc- 

 ture; hence, the forces existing in the moorings are accordingly increased. 

 These force parameter comparisons are presented in Figure 93. 



300 

 200 



% =0.065 



MAXMUM MOORING FORCE 

 WAVE-GUARD FTB,W/ = 5.4 

 GOODYEAR FT8 ' 



12 3 



Ratio of Wavelength-to-Breakwater Width, L/W 



Figure 93. Comparison of force parameter, F/yW 2 , for Wave-Guard and 

 Goodyear Tire and Rubber Company concept of scrap-tire 

 floating breakwaters, for various ratios of wavelength-to- 

 breakwater width, L/W (after Harms and Bender, 1978). 



4. Simple Mat-Type Scrap-Tire Floating Breakwater . 



Kowalski (1974) conducted tests on a simple mat-type floating breakwater 

 constructed of scrap automobile tires to prove the effectiveness of the break- 

 water for wave suppression, and to determine the construction problems and 

 durability of such a simple structure. The tests indicated that even a three- 

 tire-deep mat has a wave suppression efficiency of about 70 percent in waves 

 with a significant height of 2.5 feet when the spectral peak exists with a 



139 



