I don't think Mark Ellyatt, despite his genuine deep diving ability, is necessarily an authority on regulator design. He's quite a controversial figure in his native Great Britain... In any event, here's an article connecting him to the development of the Abyss Explorer computer:
DATELINE: 27th July 2001
DECO GUINEA-PIG
A mixed-gas diver has put his faith in new thinking on deep-dive decompression schedules to the test - by pushing a newly developed computer programme to its limits on a 160m dive off Alderney, in the Channel Islands.
Jersey-based TDI instructor Mark Ellyatt was checking out new software available for the Abyss Explorer dive computer, based on theories developed by Dr Bruce Weinke of the US National Atomic Energy Laboratory.
In essence Weinke believes that previously applied principles of deep-dive decompression, in which rapid initial ascents are followed by lengthy shallower-water stage deco stops, leads to a "cause and cure" process.
The initial ascent creates micro-bubbles and sub-clinical decompression illness (DCI), which then has to be "cured" by the stops.
Better, he says, is to carry out earlier, regular stops from depth, to avoid micro-bubble formation and cut the need for long stops later in the ascent. Overall, total decompression time is reduced.
Ellyatt's dive started with 12 minutes of bottom time at 160m on the wreck of the Baden in Hurd Deep - though by the time he surfaced, having carried out his ascent and stops on a line hung by his cover boat, the tide had whisked him eight miles from his starting position.
"The idea is that you start stops at about 80 per cent of your maximum diving depth," Ellyatt told Divernet. "Starting at 135m, I followed a schedule which involved 30 second stops every 3m, later 1.5 minutes every 3m. The last stop was for about half an hour at 6m."
Overall, he said, his stop-time had been about three hours less than with other schedules he had used.
Leaving the water, Ellyatt experienced a sense of confusion and imbalance, and worried that he might be suffering from DCI, but the symptoms cleared and he put them down to head congestion. He breathed oxygen at the surface and back on the boat for half an hour.
"We were ready for an in-water recompression treatment if necessary, with a descent to, say, 50m followed by breathing oxygen in shallower water," he said. "If necessary the boat could then have called for evacuation to a chamber while I was down there."
It is not clear whether the Weinke approach will catch on among technical divers. "Richie Stevenson says it's madness, and John Bennett knows a couple of guys who got bent using the programme on 80m dives, and says he won't touch it," said Ellyatt. "But I know that the WKPP caving guys in the US are using it."
The problem, he explained, is that the Weinke algorithms require fine-tuning to suit a specific dive, and can be misapplied. "If you're going to take it to its limits, you need to know exactly what you're doing to apply the program safely," he said.
"Even the basic thinking is being continually fine-tuned. For instance, gas consumption is heavy with all those 30 second stops every 3m, and now the thinking is for stops of one minute, spaced out a bit more.
"Weinke is careful when asked to recommend specific schedules based around the program. With some people he has recommended his deep-water stops procedure, but still added relatively generous shallow-water stops for safety."
So will Ellyatt continue to push the Weinke model to its limits?
"Yes, with careful preparation I'm happy to do that," he said. "I'm planning to do a 210m dive in the Philippines, at a site a long way from shore.
"There'll be a specialist in in-water recompression with me, just in case."
