Figure 28. Hydrolab Habitat. (From Perry Oceanographies, 1970. 

 ©Perry Oceanographies, Inc. Used by permission.) 



The habitat was positioned in 58 feet of water on a 10-foot layer of 

 coral sand. Bedrock underlies the sand. The sand surface at the habitat site 

 was leveled using a bolted steel frame with a diver-manipulated traveling screed. 

 This technique established a flat bearing surface within 2 degrees of horizontal. 



The undersea habitat structure consisted of two pressure hulls 

 connected by a pressurized crossover tunnel and attached to a rigid base. 

 Each pressure hull, a vertical cylinder with domed head, was 12-1/2 feet in 

 diameter and 18 feet long (Figure 30). A reinforced rectangular box with 

 approximate dimensions of 1 5 by 37 by 6 feet formed the rigid base. 



After jetting embedment anchors in at the site, the 5,000-pound 

 positively buoyant habitat structure was to be jacked down to these anchors. 

 However, this plan was abandoned in favor of a deadweight anchor technique, 

 primarily because no reliable embedment anchor performance data could be 

 obtained. Four 2,500-pound steel clumps were used as anchors. Once the 

 habitat structure was on the seafloor, ballast tanks were flooded, and addi- 

 tional weights were added. The total resultant load, 20,000 pounds of 

 negative buoyancy, was applied to the seafloor over the 555-square-foot 

 bearing surface. No foundation problems were experienced. 



49 



