before the system was operating at Bermuda. Dynamic coupling 

 between cable impedance and the bridge electronics was measured 

 using the actual cable and an error sensing amplifier October 

 1967 at the cable plant. Thus, no dynamic problems were ex- 

 pected. The complete Signal Cable /Sensor Array was checked 

 out for short-term water pressure integrity and sensor cali- 

 bration at the 90-inch diameter hydrostatic pressure tank at 

 Southwest Research Institute, San Antonio, Texas. This test 

 was carried out at 100 PSI pressure increments up to 1300 PSI, 

 including a 10 hour hold at 1300 PSI on 6, 7 October 1967. This 

 test was repeated on the repaired array to 1200 PSI, on 29, 30 

 July 1968. As reported earlier, structural integrity for tension 

 loads was demonstrated by proof tensioning all load-carrying 

 members. 



4. 4 Corrosion and Protective Coatings 



The only telescope components which have been exposed to 

 the ocean environment for a significant period of time and which 

 have been recovered for examination are as follows: 



a. Upper ends of the outer moorings attached to form 

 the "inverted v" on 18 November 1967 and removed 

 on 6 February 1968 after nearly 3 months at depths 

 less than 120 meters. 



b. Array of floats attached to the WHOI experimental 

 mooring at a depth of 1100 meters at Station D 

 from 23 April to 7 June 1968. 



Significant results are as follows: 



a. 316 and 304 Stainless Steel fittings suffered no 

 dete-rioration except for slight deposits of iron 

 oxide on surface scratches. 



b. Bare Aluminum floats developed a dull grey sur- 

 face color and suffered no significant deterioration. 



c. A very successful protective coating for the aluminum 

 floats was obtained using IRIDITE primer and three 

 cover coats of Neoprene paint (3MEC1706). Polyure- 

 thane paint over various primers (MIL- P-15328R, 

 and 856- 28D) proved to be very unsuccessful be- 

 cause the primers did not adhere to the metal surface. 



d. Materials in the shallow depth off Bermuda accumu- 

 lated a thin coating of a slimy and fibrous biological 

 growth. Materials at 1100 meters at Station D 

 accumulated no biological growth. 



225 



