The round hangar was supported by three 3- by 3-foot bearing plates on 

 telescopic legs. Negative buoyancy was established by 120,000 pounds of 

 lead. Except for the required revision of the foundation system for the 

 Deep Cabin, no foundation difficulties were reported. 



Conshelf Three. A third station, Conshelf Three, was placed near 

 Villefranche, France, in October 1965 (Cousteau, 1966). The 18-foot- 

 diameter steel sphere was occupied at a water depth of 328 feet by a six-man 

 crew for 3 weeks. The sphere weighed 280,000 pounds and rested on a 48- by 

 28-foot chassis that held 1 54,000 pounds of ballast, ballast tanks, and reservoirs 

 of helium, oxygen, and compressed air (Figure 25). The entire assembly was 

 supported by four legs with sediment bearing plates. Crew members obtained 

 undisturbed sediment cores by forcing water cans into the bottom sediments. 

 At the project's completion, minor difficulties were encountered in breaking 

 the feet free from the bottom. Several anxious minutes were required before 

 breakout occurred. 



Sealab I. On July 18, 1964, the Office of Naval Research, in 

 conjunction with other Navy activities, placed a manned undersea habitat 

 next to Argus Island, approximately 27 miles south of Bermuda (O'Neal et al., 

 1965; Groves, 1965). Sealab I (Figure 26) was lowered by the Argus Island 

 crane from the water surface 193 feet to the very dense coral sand bottom. 

 The bottom, which was leveled prior to the deployment, exhibited a mini- 

 mum amount of loose, soft material. The 9-foot-diameter by 40-foot-long 

 station was fabricated by the Naval Ship Research and Development Labora- 

 tory (NSRDL) (formerly Mine Defense Laboratory) at Panama City, Florida, 

 from two mine sweeper floats. The Sealab's 3,000 pounds of negative buoy- 

 ancy were supported by two 3- by 40-foot rectangular bins which doubled as 

 ballast tanks (Figure 26). The habitat housed a crew of four men for 1 1 days. 

 No foundation problems were recorded. 



Sealab II. Sealab 1 1 was the Navy's second major step in a continuing 

 man— undersea research program. Three 10-man teams occupied Sealab II for 

 approximately 1 5 days each (Pauli and Clapper, 1967). Habitation occurred 

 between August and October of 1965, 3,000 feet off Scripps Pier at La Jolla, 

 California, in 205 feet of water (Fehl, 1969; Tolbert, 1969). 



The habitat was essentially a nonpropelled submarine built to 

 withstand an internal working pressure of 125 psi. The hull was constructed 

 of 1 -inch-thick mild steel, 12 feet in diameter and 57-1/2 feet long. When on 

 the bottom, Sealab 1 1 was 26,000 pounds negatively buoyant. The bearing 

 surfaces, two 3- by 18-foot pads extending fore and aft, were designed to 

 provide a maximum bearing stress of 300 psf . 



40 



