John Zumrick

Speaker Details

Cave Explorer & Former Chief Medical Officer NEDU

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About John Zumrick

There I was at the University of California, San Diego doing and surgical residency and not to happy about it. A Navy Physician recruited me to become an Undersea Medical Officer that year which began my 14-year journey through diving wonderland. For most of this time I was stationed at the US Navy Experimental Diving Unit (NEDU) whose job, like that of the Starship Enterprise, was to go where no one had gone before. I was the chief medical officer.

Whenever a new diving apparatus was introduced, we got it first, tested it to the limits, and then if acceptable approved it for Navy use. For example, I got my first opportunity to dive a rebreather in 1974, the GE Mark 10 to a depth of 750 fsw. I then dove the Mk 14 Deep Dive System to 1000 fsw. One of my first jobs was in evaluating the US Navy MK 15 rebreather for canister duration and life support.

Of course, new gear often means new ways of diving. Our job was to develop the necessary procedures. The most involved procedures were determining times and durations for different gas mixes and any decompression tables that might be needed. I didn’t develop tables, another medical offer did, but I had a lot of opportunities to fix bends. In one case a diver had central retinal blindness in one eye after an extended Table VI. Unwilling to give up we persisted and along the way to fix this developed a new treatment table for extreme cases.

Some teams needed oxygen rebreathers for their missions. However missions often arose that were not covered by existing oxygen exposure tables, so we had to look for way to solve their problem. Sometimes that required our best guess. We often found ourselves having our test divers diving past normal limits seeing if they would convulse or not, and being prepared to make changes in our protocols to be tested the next day.

A major part of my responsibilities was to support deep saturation diving. We frequently conducted dives to 1000 fsw with the deepest being 1800 fsw. These were long dives that afforded us an opportunity to look at the physiological changes resulting from the high pressure. For example during a 1500 fsw dive on which I was a subject, we investigated micro-sleep associated with high pressure nervous syndrome (HPNS), along with respiratory changes associated with doing heavy work while breathing dense gas mixtures.

Throughout this extreme environmental testing, which included bends, and convulsions, not a single diver was permanently injured. I found out later that all of the divers there thought I was nuts when I left to explore the Underwater caves just down the road nearly every weekend.

Photo: Zumrick in a MK 14 diving system that supported diving to 1000 fsw. To old hardhat divers it looks like a MK 12 but it operates very differently

Call It The Technical Diving Revolution!- The History of Technical Diving

TEKDiveUSA.2016- Call It The Technical Diving Revolution!- The History of Technical Diving

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