The STU is a towerlike structure ik feet high with a 30-inch by 

 30-inch cross section supported on a 13-foot by 13-foot square base 

 to assure stability on soft or sloping bottoms. The structural members 

 are fabricated from A-7 structural steel and are protected with a vinyl 

 paint. This partic'olar paint was selected to ixihibit corrosion of the 

 structure and at the sajne time not to inhibit fouling activity. It was 

 felt that the introduction of a fouling inhibitor would interfere with 

 the effects of the experimental environment (inc3.uding the resident 

 organisms) on the various specimens under test» 



The tower portion of the STU is provided with adjustable shelves, 

 each consisting of a steel grating fastened to an angle-iron framework. 

 The weight of the loaded STU is approximately 7OOO pounds in air and 

 6000 pounds in sea water. 



Program^ The STU provides a means for exposing a large number of 

 specimens of various materials to the effects of the deep-ocean environ- 

 ment o The initial program, as presently envisioned, is divided into 

 two ptiaseso In the Phase I program three STU's are to be placed at 

 a depth of 60OO feet for periods of 6, 12, and 2k months respectively. 

 In Phase II, three STU°s are to be placed at a depth of 12,000 feet for 

 periods of 6, 12, and 2k months respectively. The extent of this program 

 beyond Phases I and II will depend entirely on the results obtained 

 from these first experiments « 



The first STU of Phase I has been fabricated and was emplaced in 

 5300 feet of water on 29 March I962 for a 6-month exposure o Emplacement 

 of the next STU is planned for late in FY~63, 



^erati onal Test ing . Tests at sea in .1200 and 60OO feet of water, 

 which involved the placement of the STU with a 1600-pound simulated 

 specimen load on the bottom, were conducted with the ltFU-^8 d^^ring 

 November and December I961, These tests revealed the following facts: 



1« The YFU-ij-3, a ll6->foot converted I£;u, is adequate for the STU 

 placement operation at the 6OOO -foot -depth site in favorable 

 weather o 



2. The standard Na-i^y UQK-IE depth sounder is not adequate for 

 tracking the STU during placement in 6OOO feet of water using 

 the standard recording equipment, 



3, The two devices designed and constriicted at NCEL to sense 

 any departure of the STU's attitude from a normal vertical 

 position during lowering and placement on the bottom worked 

 satisfactorily.. 



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