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Excerpted from The History of Oilfield Diving: An Industrial Adventure
by Christopher Swann (Oceanaut Press)
by Christopher Swann (Oceanaut Press)
During the first half of the 1960s, the diver Shell Oil relied upon more than any other in the Gulf of Mexico was Norman Ketchman. Like most Gulf coast divers, Ketchman was essentially a freelancer in that he got his own work; but to secure insurance coverage he operated in conjunction with Gulf Coast Diving Services, a one-man company owned by Norman Knudsen. Although Ketchman had not been in the Gulf as long as Knudsen, whose experience in the area predated offshore drilling—he was a former shrimp fisherman who started diving in the navy during the Second World War—Ketchman proved more adept at securing contracts with the oil companies, the most important of which was the account with Shell.
Since Shell had, or was about to have, a considerable amount of work in deep water, Knudsen and Ketchman decided they should demonstrate that they were able to dive with mixed gas: something no company in the Gulf was yet capable of doing. To pull this off Knudsen and Ketchman lined up Peter Edel, a chain-smoking deep-diving specialist from Connecticut.
Edel was completely self-taught. When a senior naval officer asked about his qualifications at a diving symposium, he replied “high school.” He started out doing light salvage at weekends to earn extra money, using heavy gear and a Desco mask from a 36’/11M boat. When the “scuba craze” hit, he found he could no longer compete and he turned his attention to the physics and physiology of diving. His studies led him to the conclusion that the Momsen computational method the US Navy had used to establish the helium-oxygen decompression tables was far from satisfactory.
To Edel, this was obvious. He wrote to Captains George Bond, Walter Mazzone and Robert Workman, whom he considered the pre-eminent authorities in America, and to Dr Val Hempleman at the Royal Naval Physiological Laboratory in England. Through the correspondence and discussions that ensued, Edel obtained an informal education in decompression modelling, from which solid point of departure he developed a set of helium tables that took into account the difference in gas uptake and elimination between work and rest: something Captain Albert Behnke had demonstrated in a study some time before but which, according to Edel, no one was yet factoring into decompression tables.
From theory, Edel moved to chamber dives, which he financed with donations and grants from various firms. He started out modestly enough at 200’/61M, then progressed to 20–30 minutes at 400’/123M, compressing at 100’/30M per minute with helium-oxygen and switching to a nitrogen-oxygen mixture on ascent. The longest runs were in the 170’/52M – 220’/67M range, the deepest a bounce-dive to 500’/152M breathing a helium-nitrogen-oxygen mixture. In the deep experiments Edel discovered that the depth at which he switched to nitrogen-oxygen during decompression was critical. Shifting at 150’/46M or deeper resulted in a central nervous system bend in the form of a violent vestibular disturbance. In all, including two central nervous system episodes, Edel got the bends some two dozen times.
In October 1963, Edel went to Morgan City to make his preparations with Knudsen and Ketchman. With him, he brought a Jack Browne dry suit with an attached Desco mask fitted with a side-mounted regulator. This gear was to be used on the dives in conjunction with an incredibly complicated collection of plumbing on the diver’s chest. The rest of the equipment consisted of a topside manifold connected to the regulators and gas banks, an air backup system, and a standard pneumofathometer on the diver to read the depth. Edel’s deftest touch was to hook a differential pressure gauge into the supply and the pneumofathometer to ensure that the diver was always supplied at the correct pressure. The man who was given the job of putting most of this together, on the strength of having a degree in civil engineering, was Mike Hughes, who had been working with Gulf Coast Diving Services since that March.
Knudsen and Ketchman had a rival in the helium stakes: Sanford Brothers. Sanford was the dominant diving company in Morgan City and it was common knowledge that Joe Sanford wanted his company to be the first in the Gulf to make a mixed-gas dive. To that end, Sanford had hired Jack Lahm, a US Navy Master Diver experienced in helium diving who had just retired after 22 years in the navy.
Everybody expected Sanford to beat Gulf Coast Diving Services hands down. But Sanford was running into delays. According to Tom Angel, Sanford’s assistant diving superintendent, this was because Lahm had difficulty obtaining the dome-loading regulators he needed for the gas manifold. Furthermore, when they finally arrived, it turned out that the supplier had not cleaned them properly, with the result that the first application of pressure dislodged particles of grit, which ruined them.
The story Hughes heard was that the regulators were not the same size as those shown in the US Navy Diving Manual, and were thus deemed inadequate—although they were a new model which had superseded those in the manual.
“It was actually a better regulator, with a higher flow-rate, but they did not know enough about specifications to understand that part of it,” said Hughes. They just knew it wasn’t as big as the one in the picture so they sent them back.”
In any event, when Knudsen and Ketchman went to Union Carbide to order their helium they found that Sanford Brothers already had a supply waiting to be picked up. According to Angel, the manager at Union Carbide told them Lahm was going to need all of it; but he telephoned him anyway. On learning that Lahm had postponed his dive for a week to ten days—enough time to lay in a replacement stock—he sold the order to Knudsen and Ketchman. So while Sanford waited for the replacement regulators Knudsen and Ketchman went out and made the first helium dives in the Gulf of Mexico.
Photograph of Mike Hughes, showing the elaborate chest manifold he built to allow gas switching during the dives. The tender is ‘Corky’ Downer (James Smith)
Continued in the next post
