Table III. Breaking Strength of Rope Specimens Before and 

 After Deep-Sea Exposure 



Rope 



Diameter 

 (in.) 



Breaking Strength (lb) 



Before Exposure 1/ 



After Exposure-ly 



Cotton 



1/2 



1,340 



590 



Manila 



1/2 



2,068 



Ij 



Nylon 



1/4 



1,900 



1,560 



Polypropylene 



5/16 



1,810 



1,760 



JyAverage of 2 ropes 



2/Estimated 15 percent of tensile strength of rope destroyed by marine 

 boring organisms. 



Extruded Acrylic Rod . Approximately 150 borer holes were present around the 

 solid plastic along the edge of the tape wrapping (Figure B-16). A few had started 

 to penetrate into the smooth and roughened areas of the rod. One of the holes 

 started in the smooth area was about 1/16 inch wide and 1/32 inch deep. 



Cast Acrylic Rod . Only three borers had penetrated into the acrylic rod along 

 the edge of the plastic tape wrapping. There was evidence where numerous borers 

 had attempted to penetrate into the smooth and roughened areas of the rod. 



Delrin Rod . A few borers had made very slight indentations on the surface of 

 the plastic along the edge of the plastic tape wrapping. 



Vinyl Tube (NCEL No. 388) . Fifteen borers had penetrated into the vinyl tube 

 along the edge of the plastic tape wrapping. The borer hole with deepest penetration 

 was about 1/32 inch. Approximately 100 shallow borer holes per square inch were 

 found on the lower 2-1/2 inches of the tube exposed near the sediment. 



Vinyl Tube (NCEL No. 374) . A heavy slimy bacterial growth covered the 

 entire surface of the black flexible vinyl tube, including the burlap, rubber, and 

 plastic wrappings. There was no sign of marine borer attack on the tube and wrapping 

 materials. The heavy slime growth may have prevented the borers from establishing 

 a firm foothold. After the tube was recovered and stored in a building at ambient 

 room temperature for 3 weeks, a heavy growth of fungi developed over most of the 

 exposed area. 



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