“The question of deep diving enters largely into the subject of salving of submarines and crews,” wrote Gunner Arthur D. Freshman to George Stillson when asked his opinion on the matter. “In August, 1904, the submarine Porpoise, with a crew of 12, of which I was one, was disabled and on the bottom in 160 feet of water, remaining there about 45 minutes. Since this incident it has occurred to me several times that with the present development of diving in the service we could have expected little assistance from sources outside the boat.”
He would have found little assistance from inside the boat as well, no technology existed that would enable a crew to escape a stranded submarine and swim to the surface, not even in relatively shallow depths.
To address these problems, Gunner George D. Stillson embarked on a brave new endeavor to plumb the depths of underwater human endurance, and to find the equipment, personnel and training that needed to support a well-designed deep diving program. He set up a sophisticated laboratory at the factory of A. Schrader’s Sons, Inc at the address of 738 Atlantic Avenue, Brooklyn. For open-ocean tests, he was authorized to use the resources of the Navy Yard of New York.
Inside 738 Atlantic Avenue sat a massive experimental tank, measuring 10 feet in height by 7 feet in diameter. The steel tank was interrupted on the top by a manhole cover three feet in diameter, screwed into place using heavy threaded bolts. Outside observers could look into the tank through one of four glass observation portals, all expertly fitted into the side of the tank. The tank was accompanied by an elaborate pressurization and communication system, enabling the tank to withstand being filled with the equivalent of six times surface air pressure, some 85 pounds per square inch.
The tank could be used dry to purely test physiological impacts of pressure, or flooded to test diving and underwater communication equipment. Divers were able to enter through the top hatch and descend a ladder. Once situated in the tank, the ladder would be removed and the hatch secured with wrenches. Air hoses were riveted to the side of the tank, as was the communication equipment. Though divers could signal by sound or signaling through the glass portals, the tank was also fitted with an electric bell and a telephone. In this setup, nearly any practical depth could be simulated, albeit without the effects of tide, visibility, or the variance of the sea floor.
…nearly any practical depth could be simulated
Though Dr. John Haldane and his contemporaries had significantly advanced scientific understanding of human physiology under pressure, equipment and diving techniques had not kept up. Using outdated valves and air supply systems, Divers were under huge risk of “blowing up,” where their suits inflated uncontrollably, rocketing them towards the surface. Out of control, they risked impacting objects on the surface, potentially splitting their diving suits open or breaking open their helmets, drowning them within moments. Communications equipment was primitive at best; advancements in telephone technology had not yet reached deep diving. The ability to speak underwater had previously been documented, where the human voice became nasal and metallic under pressure, loosing the individual distinctiveness so clearly recognized on the surface. Past 80 feet, or where the atmosphere is 2.5 times as thick as on the surface, whistling becomes impossible. Any deeper, and the speaker may feel actual physical resistance.
Not even the air supply system had been solved adequately; divers either used hand-actuated pumps, compressed air tanks stored on the surface, or a live source of pressure from a compressed-air system. Just a few months previous to the tests, a diver was using a torpedo air separator line for an air supply when someone on the surface opened the control valve—the men who recovered his body couldn’t tell if he’d suffocated or been crushed to death first. When diving pumps and lines were tested aboard four Navy ships, the results were stunning. The best pumps had comparably low leakage rates of just 35-36%, but most leaked well over 50% of the air pumped into them. Three of the lines had leakage rates of a stunning 100%, meaning that not one molecule of air pumped from the surface would have reached a diver. Naturally, the care and stowage of the pumps were found lacking, as leather packing, valve faces, pistons had quickly deteriorated from lack of proper care.
…most (diving pumps) leaked well over 50% of the air pumped into them…
Stillson wanted to press the outer bounds of human capability, finally coming up with accurate assessments of when the most dangerous complications of underwater diving materialized, and how they could best be mitigated. Air supply pressure was rarely sufficient in depths over about a hundred feet, and the exact nature of compressed air illness (also known as “the bends” or “diver’s palsy.”)
Complicating matters, the navy did not even have a standard diving load-out. Two different companies manufactured what was informally referred to as “Navy Standard” diving suits and equipment, but they did not contain interchangeable parts, nor were they selected based on any testing or committee analysis. Self-Contained Diving Apparatus were also to be tested. The precursor to SCUBA (Self-Contained Underwater Breathing Apparatus,) SCUDA units were in their infancy, and had fantastic potential and deadly problems in near equal measures.
Before beginning, Stillson sought the advice of several veteran divers, one of which humorously summed up both his personal knowledge and the state of the practice in his letter. “What I don’t know about diving would fill a large book,” he wrote. “I simply observed the rules and instructions that were contained in the little pamphlet that usually accompanied the diving outfits.”
“What I don’t know about diving would fill a large book,” he wrote. “I simply observed the rules and instructions that were contained in the little pamphlet that usually accompanied the diving outfits.”