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tested — the PT-1 module, composed of steel-pipe buoyancy chambers and truck, 

 tires, and the PT-2 module, composed of telephone poles and car tires. Each 

 design was 12.2 meters wide in the direction of wave propagation and was held 

 together by conveyor-belt loops. Wave attenuation and mooring-force features 

 were established based on data from 402 separate runs in which incident and 

 transmitted wave heights were recorded, along with the tension in the seaward 

 mooring line. Test results are compared with those of earlier experiments 

 made on the Goodyear floating tire breakwater. The construction of these PT- 

 Breakwater modules is outlined, along with the cost estimates for construction 

 of components. A breakwater buoyancy test was made and the flotation require- 

 ments calculated. The influence of stiffness on the mooring system was exper- 

 imentally investigated and conveyor-belt material tested to the point of 

 failure. Design curves for determining the proper anchor requirements and 

 breakwater size are given. 



Apart from the incident wave height, the transmitted wave height and peak 

 mooring force are shown to depend primarily on four dimensionless parameters: 

 the relative wavelength, wave steepness, relative breakwater draft, and 

 breakwater aspect ratio. The wave attenuation performance of PT-Breakwaters 

 improves as either wavelength or water depth decreases, or the wave steepness 

 increases. The shelter afforded by a particular PT-Breakwater is strongly 

 dependent on the incident wavelength, L: substantial protection is provided 

 from waves that are shorter than the width, B, of the breakwater but very 

 little from waves longer than three times the width of the breakwater. 



The wave attenuation performance of PT-1 was found to be superior to 

 that of PT-2 and the Goodyear breakwater: for L/B = 1 and deep water with 

 H/L = 0.04; for example, the wave height transmission ratios are approximately 

 0.6, 0.4, and 0.2 for the Goodyear, PT-2, and PT-1 breakwaters, respectively. 

 For the conditions investigated, the peak mooring force increases approxi- 

 mately with the square of the wave height, more precisely: F ^ H n where 

 n = 1.5, 2 and 2 for the PT-1, PT-2, and Goodyear breakwaters, respectively. 



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