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Technical Diving Articles

Mermaids Dive Career Development Center (Pattaya, Thailand) is extraordinarily lucky to have great scuba diving internships and professional traineeships honed over many years of experience making us a first class scuba dive training academy for all serious divers. Along side this we have built an incredible base of highly skilled dive professionals that have been working in the dive industry for a long time and with related or interesting backgrounds. Mr. Steven Burton our technical Director in Mermaids Jomtien, Thailand – is one of these very special “diving hands”. Steve has been responsible for assisting in planning world record diving practices, establishing his own principles in diving adopted by others. Here at the facility Steve is the only qualified ASSET (Association of Scuba Service Engineers and Technicians) instructor in Asia. With a wealth of engineering behind him – Steve is an ASSET indeed. Please find some very interesting articles written by the “in-house mad-scientist” himself….Mr. Steven Burton.

(Article 1) The Pain Principal

Elements of extreme dive planning

As human beings we are the physically weakest of all mammal species. Pound for pound, our muscle strength just doesn’t match up against any of our nearest primate relatives. A playful adult chimp half our size has muscles 7 times as strong as a man and could tear its trainers arm off if threatened. What sets us apart from other species is our brain and our ability to invent, plan, manufacture and create theories for the way the world around us behaves. This allows our physically weak species to exert control over most other life on this planet.

This ability to observe and invent, and to discover the underlying math that correctly predicts the phenomena that we observe during our daily lives has profound implications for our species. The famous inventor Isaac Newton observed an apple falling from a tree. Within a few years, his mathematics and laws of motion were predicting planetary motion, and in the last century guided Apollo rockets to the moon.

When the theories do not match the observed phenomena, man must think again. For the diver the implications of this simple statement are easy to grasp. Any dive planning method that causes Death, pain or physiological damage requires a rethink. This has been the driving force for decompression research for more than 150 years. This series of articles will look at the latest theories for planning of extreme dives, and their implications for recreational divers.

Deriving the underlying laws and predictive mathematics for diving physiology, safe decompression, Oxygen toxicity tolerance, narcosis, and HPNS(High Pressure Nervous Syndrome) have challenged the minds of the world’s brightest scientists. That many of the victims of ‘incorrect guestimation’ fail to survive and be part of the ‘observable phenomenon’ database further hampers progress.

As a first topic in this series we’ll take a more in depth look at decompression.

Decompression

From its first observation by the French Physiologist Paul Bert in 1878 through to Haldane’s 1905 research, Bühlmann’s 1990’s research, and the latest RGBM work by Bruce Weinke at Los Alamos Labs in the USA – A key feature of them all is to attempt to accurately predict the human body’s response to working at depth and then ascending to the surface.

The earliest tables were entirely empirical, based on measurements on what caused a military diver pain. Navy divers are notoriously tough, so one can imagine what pain level had to be reached before they complained of being ‘bent’. It’s not the sort of pain level that you and I would like to endure on every recreational dive.

The first serious attempt at reducing the pain threshold or ‘barotrauma insult’ to the body to sub-clinical levels by actual measurements of bubbles flowing around the body was produced by Buhlmann. His vast database of bubble grade measurements from divers enduring hundreds of hours of chamber dives with mixed gases produced a massive table of ‘half times’ and ‘m-values’ The introduction of Buhlmann tables derived from these measurements still represents a watershed in decompression research, and marked a move away from ‘pain based’ research.

Further work still on newer models is proceeding with an almost entirely mathematical approach. The use of animals for medical research is well known. Early deco research used goats in hyperbaric chambers. A hundred years ago, ‘tech diving hungry goats’ were taken for simulated deep dives in a chamber and subsequently decompressed ‘to the surface’ to test table limits. If the goat walked out of the chamber following the dive, it was assumed to be OK. If it couldn’t or wouldn’t get up to walk out, it was assumed to be bent. Later work within the last few years has used salmon or even gel samples in Petri dishes to research deco tables.

The test of any good deco theory is how well it performs against the known database of the human body’s tolerance to pressure changes. No matter how elegant the theory, if divers get hurt applying it’s predictions, it is of questionable use for its intended purpose.

Conclusions

With extreme Trimix deep divers pushing open circuit depth limits beyond 1,000 ft and commercial research divers breathing hydreliox in chamber environments descending past 2,250 ft, a couple of important questions remain:

Why is there such a push to create super fit divers to undertake extreme dives; if the decompression model is correct, then shouldn’t anyone be able to use them?

Plainly, with so many severe injuries occurring to extreme divers in recent years, plus the continual background of DCS incidents suffered by otherwise healthy recreational divers within dive tables limits, our knowledge still has a long way to go before we have ‘full understanding’ of decompression science.

We really should depend more on our proven superior intellect as human beings, rather than our less than optimum physiological construction to overcome the challenges of the deep.

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