68 DESIGN, CONSTRUCTION, AND OUTFITTING 



4. The arrangement should include four separate areas: entry, laboratory, galley, and 

 living space. 



Reason : This basic arrangement worked well with Sealab I. 



5. The atmosphere was to consist of approximately 85 percent helium, 4 percent oxygen, 

 and 11 percent nitrogen. 



Reason : Controlled experiments and experience in Sealab I confirmed this to be a proper 

 mixture to minimize narcosis, support life, and preclude complete air purging. 



6. Certain effects of helium were to be accounted for, primarily in the heat transfer area; 

 the coefficient of heat transfer of helium being approximately six times that of air. Extra in- 

 sulation must be provided. 



Reason: Heat losses were not calculated in Sealab I, and no controlled tests were run. The 

 refrigerator, a thermal electric type, never operated satisfactorily. 



7. Temperature was to be held at 88° F and humidity at 60 percent relative. 

 Reason : These seemed comfortable in Sealab I. 



8. Primary power was to come from the shore, secondary power from the surface staging 

 vessel as part of the umbilical cord. Communications, secondary gas supply and sampling, 

 and compressed air for external tools used were also to come down the umbilical. 



Reason : Assuming the integrity of the primary power source, the staging vessel could de- 

 part and not cause an immediate abort or dangerous situation. Primary gas supply was from 

 an external bank of bottles. Sealab I was terminated due to impending heavy weather. This 

 development would make Sealab U more independent. 



9. There were to be a maximum number of portholes with the capability of seeing the bot- 

 tom periphery of Sealab n. 



Reason: A near -fatal accident occurred in Sealab I. An unconscious man was rescued 

 only when his bottles bumped the side of Sealab I; he was not visible from within. 



10. The atmosphere-water interface was to be as close to the bottom as possible. 



Reason : With no good data or information as to the extent of excursion dives deeper than 

 saturation pressure, deeper depths could be reached from a higher saturation pressure. 



11. Reduction of the interior volume was to be made wherever possible by use of interior 

 tanks, dead spaces, etc. 



Reason : Any decrease in interior volume was a decrease in the amount of helium required 

 and thus a cost savings. 



12. Sealab n was to be painted white. 



Reason: The international orange of Sealab I would not have the acuity that white does 

 underwater; hence easier sighting in marginal visibility conditions. 



There were a few other more minor considerations but the afore -mentioned were about 

 the extent of information the shipyard received in the forms of design parameters. 



It became apparent very early that the biggest problem area in Sealab I was in the sub- 

 merging operation. Railroad axles at 300 lb each were used as variable ballast. These were 

 loaded by hand, and when sufficient negative buoyancy was reached, lowering was by a sling 

 and whip arrangement from a crane on the surface. A 9- in. nylon line was used, and the effect 

 was similar to a huge yo-yo on a rubber band. Once on the bottom, additional axles were added 



