allow easy fastening of the tying material, forming a tightly secured bundle. 

 After construction, the modules are easily transportable for assembly at the 

 project location. A prototype installation is shown in Figure 79. 



A prototype scrap-tire floating breakwater assembled according to the 

 Goodyear Tire and Rubber Company concept has high-strength characteristics (as 

 high as 56,000-pound breaking strength on a 6.5-foot-spaced longitudinal and 

 transverse grid) , and can absorb great amounts of energy by yielding and 

 deforming when overloaded. Candle and Fisher (1976) reported elongation of 

 more than 30 percent in both directions. The type of interlocking hardware 

 to be used in the construction, which depends on the desired strength and 

 expected service life of the installation, represents about 35 to 50 percent 

 of the total cost of the breakwater; labor and the mooring system represent 

 the remaining cost. Any temptation to economize on tying materials should be 

 avoided as the interlocking material can be the weak link in the entire 

 system. 



Of the interlocking materials investigated by Goodyear Tire and Rubber 

 Company as of 1976, specially manufactured, unwelded open-link chain (1/2-inch 

 diameter) proved to be best-suited for the construction of scrap-tire floating 

 breakwaters. The open-link chain has adequate strength, is easily handled, 

 and has a long life expectancy in seawater. It is also easily interconnected 

 with the use of simple handtools. The use of dissimilar metals should always 

 be avoided in a marine environment. 



a. Prototype-Scale Wave Attenuation Effectiveness . Prototype-scale 

 mooring load and transmission tests for the Goodyear Tire and Rubber Company 

 floating tire breakwater concept were performed at the U.S. Army Coastal 

 Engineering Research Center (CERC) (Giles and Sorensen, 1978, 1979; Giles and 

 Eckert, 1979). The tests were conducted in CERC's large wave tank which is 

 6.1 meters (20 feet) deep, 4.6 meters (15 feet) wide, and 194 meters (635 

 feet) long. Waves of constant period and height were produced by a piston- 

 type generator. 



Two floating tire breakwaters (one containing 8 Goodyear modules, the 

 other 12 modules) were tested. The breakwaters included modules constructed 

 with 14- and 15-inch automobile tires, two modules wide across the tank and. 

 four or six modules along the tank (the width of the breakwater in the direc- 

 tion of wave advance). A schematic diagram of the wave tank setup is shown in 

 Figure 80. Incident and transmitted wave heights were measured with fore-and- 

 aft wave gages, and seaward mooring forces were measured with a load cell. 

 Anchor locations were adjusted to produce mooring line slopes compatible with 

 field conditions. 



Each breakwater section was tested using wave conditions commonly found on 

 a sheltered body of water such as a reservoir or bay. A total of 165 combina- 

 tions of wave period, wave height, structure width, and water depth were 

 tested. Wave periods ranged from 2.64 to 8.25 seconds. Wave heights varied 

 from 20 to 140 centimeters (0.6 to 4.5 feet) at water depths of 2 and 4 meters 

 (6.5 and 13 feet). Each combination of wave height, wave period, water depth, 

 and structure width was tested for 5 minutes, which allowed sufficient time to 

 determine the pertinent forces and wave heights. 



126 



