(b) All of the 3-foot-long plastic rods and tubes. Shallow-to-deep holes were 
made on the surface of these materials and were restricted to an area where 
a large wooden bait piece was fitted around each plastic specimen, and 
(c) Manila rope specimens, The borers together with microorganisms destroyed 
the usefulness of the rope. The destruction was complete and rapid by marine 
borers measuring 1/4 inch in diameter which were found throughout the entire 
length of the rope specimens. Some of the borers had completely penetrated 
through the 1/2-inch-diameter rope. 
7. Silicone rubber electrical cable insulation was deteriorated by nibbling and 
biting action of some marine animals. 
8. The following materials were not affected by marine organisms: rubber 
tubing (vacuum), coral concrete, acrylic sheet, Saran and polyethylene films, nylon 
nuts and bolts, plastic electrical insulating tape, nylon parachute shroud line, ethy! 
cellulose cable clamps, and various electrical cable insulating materials such as 
neoprene, butyl rubber, natural rubber, Teflon, polyethylene, FEP, Bakelite, PVC, 
and nylon. 
CONCLUSIONS 
1. The materials listed under Finding No. 8 are considered to be suitable for 
deep-ocean use in an environment such as at Test Site I. 
2. Materials such as pine and greenheart wood, Manila and cotton ropes, 
silicone rubber insulation, friction tape, and jute fibers are susceptible to total bio- 
logical destruction and are not suitable for deep-ocean use. 
FUTURE PLANS 
Investigation of the effects of the deep-ocean environment upon materials is 
continuing. 
Test Site | (Nominal Depth of 6,000 Feet) 
STU I-4 which had been exposed at this test site since June 1964 at a depth of 
6,800 feet was recovered in July 1965. The materials have been examined for bio- 
deterioration and writing of a report has been initiated. STU I-2 which had been 
exposed at a depth of 5,640 feet since October 1963 was retrieved in October 1965. 
The materials are presently being examined for biodeterioration. 
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