

1 1 



— r 







T 





— i — j+1 1 







Goodyear 













/+ X 





- 



LEGEND 

 L/B 













*/ ^v 



/ ^^_ J - » 0.1* 



" 



- 



•- 2.0 to 3.7 

 » 1.3. to 2.0 

 + 1.0 to 1.3 

 x 0.8 to 1 .0 







1 



• 



+ 















y 



A » 













1 / 



t 



• 











- 





• 

 • 



! 







| 





0/d B/O D (m ) 

 0.16 12.0 0.6 5 



1 1 1 



" 



20 40 .60 .80 1.00 1.20 1.40 1.60 



Incident Wave Height H ( m ) 



Figure 52. Goodyear peak mooring-force data 



(Giles and Sorensen, 1978; d = 4.0 m) . 



For a given wave height and length, the mooring forces on the Goodyear 

 breakwater are clearly much lower than those for a PT-Breakwater of equal 

 size. This finding is attributed principally to three factors, the relative 

 importance of which cannot be quantified at this time: 



(1) The transmitted wave for the PT-Breakwater is smaller than 

 that for the Goodyear breakwater; i.e., different levels of energy 

 dissipation occur on each structure (wave breaking and impact, etc.). 



(2) Different mooring systems were utilized. The importance of 

 this has already been demonstrated with regard to the PT-1 breakwater 

 (see Table 4). 



(3) The Goodyear breakwater design stretches extensively under 

 load, being very pliable throughout. This influences or perhaps even 

 dominates the mooring dynamics and load transmission characteristics. 



VI. SUMMARY AND CONCLUSIONS 



Two prototype-scale PT-Breakwaters were tested in CERC's large wave tank 

 using regular waves: the PT-1 module, constructed of truck tires and steel 

 pipes in waves up to 1.8 meters high, and the smaller PT-2 module, constructed 

 from automobile tires and telephone poles in waves up to 1.5 meters high. 

 Wave transmission and mooring-load characteristics were established based on 

 data from 402 separate runs in which incident and transmitted wave heights 

 were recorded, along with tension in the seaward mooring line. 



In the course of the investigation, it became increasingly evident (during 

 construction, crane operations, and early experiments) that the PT-1 break- 

 water was more rugged and could potentially function and survive under more 



50 



