Online with the RGBM: A Modern Phase Algorithm and Diveware Implementation

By Bruce Wienke
Senior Project Leader in the Nuclear Technology/ Simulation And Computing Office at the Los Alamos National Laboratory

Both Suunto and Abysmal Diving have released products incorporating a modern phase algorithm, called the Reduced Gradient Bubble Model (RGBM), for diving. An iterative approach to staging diver ascents, the RGBM employs separated phase volumes as limit points, instead of the usual Haldane (maximum) critical tensions across tissue compartments. The model is inclusive (altitude, repetitive, mixed gas, decompression, saturation, nonstop exposures), treating both dissolved and free gas phase buildup and elimination. NAUI Technical Diving employed the RGBM to schedule nonstop and decompression training protocols on trimix, heliox, and nitrox while also testing gas switching alternatives for deep exposures.

Applied Theoretical Physics Division; Los Alamos National Laboratory; Los Alamos, N.M. 87545

"INTRODUCTION"
Much interest in the use of mixed breathing gases, across a spectrum of diving, has errupted in the past few years or so, mostly in mixtures of nitrogen and oxygen that differ from pure air, and especially those with higher oxygen content than air, termed enriched, which can be employed efficiently in shallow diving. Non-enriched mixtures of nitrogen/oxygen (nitrox), helium/oxygen (heliox), and helium/nitrogen/oxygen (trimix), of course, have long been employed commercially in deep and saturation diving. Recently, mixtures of hydrogen/oxygen (hydrox) have also been tested. A closer look at these inert gases in a range of diving applications is illuminating, particularly gas properties, advantages and disadvantages, and interplay.

A keynote in mixed gas diving is the oxygen partial pressure. Inspired partial pressures of oxygen must remain below 1.6 atm (52.8 fsw) to prevent toxicity, and above .16 atm (5.3 fsw) to prevent hypoxia. This window, so to speak, is confining, some 1.44 atm (47.5 fsw). Balancing diver mobility within this window at increasing depth is a delicate procedure at times.

DAN discusses the dangers of oxygen toxicity when using nitrox as a breathing gas.  By Dr. E.D. Thalmann, DAN Assistant Medical Director; Captain, Medical Corps, U.S. Navy (retired)

It's a fact: we need oxygen to live. It's because of the way our cells use oxygen that we are able to breathe, exercise, and even think. In each of our cells, structures called mitochondria take the oxygen which diffuses in from our blood, disassemble it into its two component atoms (remember, oxygen - O2 - is composed of two oxygen atoms), and then hook some available hydrogen nuclei to them to form water.

Extract: We are who we think we are, and we can do what we think we can do, if we maintain a positive self-image. Self-image is really concerned with self-perception and self-communication. At times, we can talk ourselves into having a bad day, convincing ourselves that we are powerless to change the outcome. Few can talk themselves into a good day. Our perception of ourselves is the basis for self-talk, which in turn, influences performance, which creates self-image, more self-talk, more imaging, and so on back and forth. When we blow a neutral buoyancy control exercise, we can often talk ourselves into the same rut next time. Negative self-image feeds on failures.

HEAD GAMES OF DIVING;  B.R. Wienke

As divers, we often view our performance in terms of the manueuvers we can or cannot do. Skills, and their respective levels of development, are certainly of concern to both the beginning and accomplished diver. In grooving motor skills and attempting to enhance our performance, it appears useful to consider a number of competing factors impacting physical performance and mental perception, and especially their interplay, the so called head games of competitive endeavor.