INTRODUCTION 
As part of a research program to determine the effects of the deep-ocean 
environment on various engineering materials, the U. S. Naval Civil Engineering 
Laboratory has placed six Submersible Test Units (STU's) on the ocean floor and five 
have been recovered. The first of the series, STU I-1, was emplaced at Test Site | 
in March 1962, followed by STU's I-2 and I-3 in October 1963 and STU I-4 in June 
1964, 
STU II-1 was emplaced at Test Site II in June 1964, followed by STU II-2 in 
April 1965. The location of the two test sites is shown in Figure 1. 
STU I-3 was the first to be recovered, after 4 months of exposure at a depth of 
5,640 feet. It was loaded with 1,367 test specimens of 492 materials. The effects of 
deep-ocean marine fouling and boring organisms upon these materials have been 
reported in Reference 1. 
STU II-1 was the second STU to be recovered, after 6 months of exposure in 
2,340 feet of water. It was loaded with 2,385 specimens of 603 materials. The effects 
of deep-ocean marine animals upon these materials have been reported in Reference 2. 
Preliminary results of corrosion of metals have been reported in Reference 3. 
On 25 February 1965, STU I-1 loaded with 1,318 test specimens of 396 materials 
was the third STU to be recovered after 3 years (1,064 days) on the ocean floor in 
5,300 feet of water (Figure 2). This report presents the materials and methods employed 
for attracting, collecting, and evaluating deep-ocean fouling and boring organisms, 
and the results of field and laboratory investigation of the recovered materials from 
SY Hele 
A fourth STU (STU I-4) was recovered on 18 July 1965 after 13 months exposure 
at a depth of 6,800 feet. The fifth STU was recovered on 22 October 1965 after 
2 years exposure at a depth of 5,640 feet. The materials from both STU's are currently 
being evaluated and examined for corrosion and biodeterioration. 
RESEARCH METHODS 
Oceanographic Information 
Concurrently with the STU program, numerous oceanographic and biological 
data-collecting cruises to the STU sites have been conducted.4 These have produced 
information about the environmental parameters such as salinity, temperature, oxygen 
