Figure 8. Specimens of Manila hemp ropes exposed in harbor mud 1 year. 



There were no significant differences in the hardness or tensile 

 strength of specimens of plastic sheeting exposed for 2-1/2 years in the 

 anaerobic bottom sediments, in the aerobic near-surface waters, or in 

 the laboratory (Table 1). 



Ropes 



Although synthetic fiber ropes changed somewhat in color after an 

 exposure of 2-1/2 years in the ocean, they were weakened only slightly, 

 if at all. Table 2 indicates that the ropes exposed in the harbor mud 

 may have been a little weaker than unexposed ropes or those that were 

 exposed in aerobic near-surface waters. In view of the small numbers of 

 specimens tested, however, the differences were too small to be significant, 



Electrical Cables 



No physical tests were performed on the sections of insulated 

 electrical cable (Figures 9 and 10). Microscopic examination of the 

 outer covers of the cables disclosed that the natural rubber covers 

 underwent surface deterioration. The small brackets holding the cable 

 sections to the panels protected the surface of the underlying rubber. 



10 



