Figure 33. Photomicrograph of borer damage on surface of a vinyl 

 tube. Some of the borer holes are about 1/32 inch in 

 diameter and about l/32 inch deep. 



Wrappings Around Plastics. The burlap wrappings were moderately deteriorated 

 by microbial activity, and the material could easily be torn apart by hand. The rubber 

 electrical tape wrappings were not affected by marine organisms, although there was 

 a light hydroid growth on the rubber material. Slight cracks were present in the rubber, 

 and these were probably produced by the effects of the deep sea environment. The 

 plastic tape wrappings were not affected by marine borers; however, there was some 

 hydroid growth on them (Figure 34). 



Electrical Insulation (0.015-Inch Thick) on No. 16 Wire. In the laboratory, 

 the insulation of the 15-inch-long wire specimens was examined under a stereoscopic 

 microscope for signs of deterioration. In addition, tests of insulation resistance (non- 

 destructive) and voltage breakdown (destructive) were conducted on these specimens. 

 The results of the electrical tests are presented in Table 6. 



The entire surface of the silicone rubber insulation, exposed near the sediment, 

 was roughened, and the thickness of the insulation was reduced considerably by the 

 nibbling and chewing action of some unknown marine organisms. The surfaces of 

 other insulations, such as polyvinyl chloride, polyethylene, government rubber styrene 

 (GR-S), and neoprene were not affected. A silicone rubber cement which was used to 

 seal the ends of the wire specimens was neither affected by marine organisms nor by 

 the deep sea environment. 



34 



