CONCLUSIONS 



1. The following materials are susceptible to total biological destruction and are 

 not suitable for use in the deep ocean: untreated pine, fir, redwood, cedar, ash, 

 oak, and maple; Manila and cotton ropes; and burlap (jute fibers). 



2. The following materials are probably not susceptible to biological deterioration 

 in the deep ocean: rubber vacuum tubing; acrylic sheet; nylon nuts and bolts; 

 nylon and polypropylene rope; ethyl cellulose cable clamps; laminated plastic 

 sheets; glass slides; and electrical cable insulations composed of neoprene, butyl 

 rubber, natural rubber, and polyvinyl chloride. 



3. The 3-foot-long plastic rods and tubes (except vinyl tube, NCEL No. 338), the 

 polyvinyl chloride pipe, and the electrical cable insulations (except silicone rubber) 

 may be suitable for use in the deep ocean if they are not placed in direct contact 

 with wood. 



FUTURE PLANS 



The research program to determine the effects of the deep-sea environment on 

 engineering materials is continuing. 



A STU (1-2) which was exposed for a period of 2 years at a depth of 5,640 feet 

 was recovered in October 1965. The materials aboard this STU are currently being 

 examined, tested, and evaluated for biodeterioration. 



Plans are being readied to retrieve STU 11-2 in May 1966. It will have been 

 exposed for 1 year on the sea floor at a depth of 2,400 feet. 



ACKNOWLEDGMENTS 



Dr. Ruth D. Turner, Museum of Comparative Zoology, Harvard University, 

 identified the marine borer specimens. Dr. Jan Kohlmeyer, Institute of Fisheries 

 Research, University of North Carolina, examined the wood specimens for fungi. 



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