Please take the time to review this wonderful article wrote by Joel Silverstein about Bill

It’s safe to say that if it weren’t for Bill Hamilton, technical diving as we now know it would not exist.

An underwater physiologist with deep roots in the commercial and scientific diving industries, in the late 1980’s he suddenly found himself without a challenge. “They had pretty much learned how to do what they needed to and so weren’t doing much in the way of physiological studies,” says Hamilton. “A
lot of the excitement had gone out of it.”

Enter Stuart Clough and his dream of building a commercially viable rebreather. Clough brought Hamilton in on the project. In one fell swoop, Hamilton was hooked up with guys like Rob Palmer, Rob Parker, and Bill Stone.

Remember that at the time, the world of decompression was a quite different one.

Mixed gas schedules were the expensive, closely guarded secrets of oil companies. If you weren’t in their loop, you were in the dark, and the few non- commercial divers who had tried to use mix wound up with serious decompression hits.

All that began to change with dough’s rebreather projects. “We got some talk going about the use of helium, and even neon, and then the word got out,” says Hamilton. “It wasn’t long before Parker Turner (one of the founders of the Woodville Karst Plains Project in Florida) asked me if I could help them put
some helium into their mix.”

Since then, the list of divers Hamilton has helped divers such as Sheck Exley, George Irvine, Rob Palmer, Bill Stone, Rob Parker, Jim Bowden, to name just a few. With tech diving now coming out of its infancy, and the number of training fatalities start to add up, it seems a good time to re-visit Hamilton and get his views on where we’ve been and where we’re going.

Q: Coming from a commercial background, did you think guys like Stone and Palmer were crazy when they first approached you and told you what they wanted to do?

A: Well, I had met plenty of crazies in the commercial world, so, no, I didn’t. I thought they were explorers. Now, there were some that I thought didn’t know what they were doing and a few that I didn’t
think was careful. But that sort of thing is usually self-correcting.

Q: You mean they kill themselves.

A: Sometimes.

Q: Now, back when you first began providing these guys — who I guess we would now recognize as the first tech divers — with decompression information on mixed-gases, there wasn’t much basis for it in the way of actual dives. Did you have any problems with that?

A: No, because they were going to make the dives anyway and they would have used air, which would have been a lot more dangerous. They needed the techniques and the tables, and I was hungry for the information.

Q: In the US, the number of decompression accidents among tech divers seems to be on the rise—

A: I don’t like calling decompression sickness an accident because I don’t think it is one. You should expect it and be prepared to deal with it. And in most cases, it can be dealt with without injury.

Q: Okay, taking the tack that the bends aren’t an accident, what do we think we know about decompression that we really don’t.

A: Well, a little knowledge is always a dangerous thing. Too many people put too much faith in these equations. They’re useful tools and they do work, but they’re just a way of representing an empirical event. They don’t represent what’s going on in your body.

Q: Where do you stand on the deep-air controversy?

A: Okay, here’s where I get in trouble with Brett (Gilliam). Deep air is dangerous. I’ve studied narcosis in the laboratory, and I know how bad it is when you must deal with a problem when you are narcotized. If something goes wrong, narcosis can kill you.

Q: So why is deep-air diving still being taught as a formal discipline?

A: I don’t know why. Actually, it is me way some people earn part of their living. The whole reason technical diving was invented was to avoid deep-air diving. Now some people argue that you need to experience deep air if you’re going to do deep technical diving, and I don’t have a problem with that concept, under the right circumstances. But don’t go sticking your neck out, because it’s a risk you just don’t need to take. You can’t calculate narcosis in the same manner that you do your decompression because oxygen is at least as narcotic, if not more so, than nitrogen. And when you’re in trouble with narcosis while air diving, you are, by definition, a long way from the surface. All your problems are magnified tremendously.

Q: Would you put a depth limit on air?

A: I wouldn’t because there are too many variables — individual differences, what the diver is doing, the environment, temperature, stress levels, visibility, current, et cetera. If I had to, I’d say 50 meters is a
good stopping point. Then you’d have to factor in all the variables and the limit may need to be somewhat shallower.

Q: There’s been some talk that deep-air may cause physiological problems, such as impairing the ability of blood cells to fold as they move through small capillaries.

A: I’m not familiar with data that says that, so I’ll have to reserve judgement. But I don’t think it’s much of a problem. We’ve had people in our laboratory down to the equivalent of 400 feet on air and, while they were pretty well narked, we didn’t see anything else. And if you don’t see it, then the phenomenon you’re trying to observe may not be very important operationally.

Q: The use of deeper stops is starting to become more prevalent. Any opinions?

A: Well, a colleague of mine, Eric Baker, who’s also translating Buhlmann’s book into English, has come up with a modification to the algorithm to calculate deep stops but I can’t say much more about it right now. Divers who are doing it, are doing it on an ad hoc basis. And it’s now getting the attention of one of the experts so we’ll see what comes of it. But when you start adding stops arbitrarily, you can screw up the rest of the dive, so you have to be careful. You have to consider the whole picture.

Q: What do you think about the decompression software programs that are on the market?

A: Well, the thing that bothers me about them is the way they measure conservatism. If you put in a 20% conservatism factor, well, what does that mean? I don’t know and I don’t know if anyone else does either. But I haven’t heard of anyone getting themselves into real trouble with them, or with a dive
computer for that matter. There have been some cases ofDCS.

Q: Does physical fitness play a role in decompression?

A: Fitness is very important but it’s probably more helpful in terms of your ability to perform, for instance to swim, than at a cellular level. Someone who’s extremely fit can probably decompress a bit more aggressively than someone’s who isn’t. But someone who’s overweight could have problems
because of circulation and the way fat takes up gas.

Q: Should all tech divers be routinely tested for PFO?

A: That’s a tough question. We’re fairiy sure that people have bubbles on what I’d call ordinary dives.
Now, some bubbles are tolerable, but we don’t really know the point at which they become troublesome.
If you start to have underserved problems, then you should have it checked. But the pressure pattern in
the heart doesn’t just push bubbles from the right side to the left because there’s a hole there. The flow is
more likely to be in the other direction because the pressure is higher on the left side. You have to have a
PFO and some kind of a pressure disorder, such as you get when doing a valsalva maneuver, or when
you’re upside-down or coughing or something. But I don’t think the returns are in on this one yet.
Researchers are trying to get data on decompression and PFO but I don’t expect the relationship to be terribly strong.

Q: What don’t we know about decompression that we will know 10 to 15 years from now.

A: How about the answers to most of the questions you’ve just asked. We’re still trying to find better mathematical algorithms to model what happens to the body during decompression. We don’t have that down at all. What we have works but it’s not under control. And there are all kinds of questions about oxygen exposure and repetitive diving that need answers. Unfortunately, though, when it comes to decompression, we’re probably not going to get orders of magnitude better at it. We’re pretty close the edge of the envelope now. It’s the variables we could get a better handle on, such as temperature and exercise. We know they have effects, and we know the direction to a certain extent, but it is hard to include these in a decompression calculation in a quantitative way.

On September 16, 2011, Bill passed away surrounded by his family and close friends, a mere three weeks after he and Kathy participated in this workshop in Gdansk, Poland.Billy Bob was special. By the way, do you know any other 81-year-olds who still updated their resumes? It’s often said that people mellow with age. The exact opposite is true of Billy Bob who productively used every waking minute of every day.When asked which approach to decompression was the best idea or theory his response represented his sense of humor and operational experience: “It is better to do something, than not.”Born in Midland, Texas, Bill pursued a degree in liberal arts at the University of Texas, followed by a Master’s degree in animal reproductive biology at Texas A&M. The University of Minnesota conferred his doctoral degree in physiology and biophysics in 1964. Along the way Bill joined the U.S. Air Force, earning the rank of Major and serving as a jet fighter pilot during the Korean War and again in Vietnam, where he earned the Distinguished Flying Cross, Air Medal, and other decorations.As a Life Support Officer he helped solve equipment problems on unsuccessful bailouts, which earned him a National Academy of Sciences recommendation to NASA as a Scientist Astronaut.Eventually, Bill left the Air Force with his wife and four children and headed to Buffalo, New York, in 1964, where he met Heinz Schreiner and began his work in the undersea world.Bill worked as a scientist and director of a leading environmental physiology and diving research lab called Ocean Systems (a division of Union Carbide) based in Tarrytown, NY. He conducted extensive research on the effects of gases both under increased pressure and in hypobaric environments. This work led to the development of decompression modeling tools and operational procedures for divers, astronauts, hyperbaric chambers, and tunnel and caisson workers. In 1965, Bill was both the physiologist and test subject on the first manned laboratory saturation ‘dive’ to the continental shelf pressure of 12 ATA (200 msw). Bill met Kathryn Faulkner (aka ‘Ruby Lips’) on an Eastern Airlines Shuttle, which turned into a 40-year marriage that has created an international family of friends and colleagues. Kathy played a pivotal role in Bill’s life, becoming a mother to his children and then grandmother to their children and managed the business aspects of Hamilton Research. It was rare for Bill to be at an event without Kathy close by In 1976, Hamilton Research, Ltd. became the premier organization for decompression and hyperbaric research developing procedures and techniques to mitigate the effects of High Pressure Neurological Syndrome and the development of the Diving Computational Analysis Program (DCAP), co-developed with David J. Kenyon. Bill was also the principal investigator of the NOAA Repex Oxygen Exposure tables – the basis for most every oxygen exposure calculation method used today for saturation and repetitive exposures to oxygen in breathing mixtures. In the late 1980s, Bill stepped out of his traditional role with commercial and military clients and into the world of sport divers by creating project-specific custom decompression tables. He opened up a whole new world of underwater exploration for the free-swimming untethered diver, the birth of ‘technical diving.’ Bill was on everyone’s invite list for conferences and workshops around the globe. Bill was generous with his time and advice, and he served by volunteering wherever he could. That was his nature. Bill was recipient of significant honors and awards from many diving and science organizations. His forward thinking of how divers would survive underwater is arguably the basis for all extreme-exposure diving today. His modus operandi was to get the job done right and then have a good time with the people around him. His work with decompression tables, physiological effects of gases, and methods of managing exposure to oxygen were instrumental in the origination and development of the new field of “technical diving.” Bill served on numerous Boards of Directors of diving and medical societies and was a member of many, including Mensa. Hamilton contributed to, and authored, numerous scientific and technical papers, reports, and in particular, diving medical and safety workshop proceedings (http://archive.rubicon-foundation.org). Billy Bob was predeceased by his first wife Beverly, son Beto and daughter Kitty. He is survived by his wife of nearly 40 years, Kathryn “Ruby Lips,” daughters Lucy and Sally, sisters Emily and Ann, grandsons, Felix, Bobby, Zach, Tyler and Truman and an untold number of adoring fans. He is missed. Billy Bob, thanks for your lasting contributions.

Took it from: Proceedings of Validation of Dive Computers Workshop 24 August 2011, Gdansk, Poland Editors: Lesley Blogg, Michael Lang and Andreas Møllerløkken, Editors