Hello Beck:
We will work on the question of
Abyss Advanced Dive Planning Software on this thread. The Abysmal company sells planning software for technical divers to allow development of dive plans for excursions deeper than 200 feet and using helium with later switches to nitrox. While the software could be used to plan any dive, a simpler dive computer could perform the functions for the shallower descents and ascents.
The program for the Abyss can be used to program the
Explorer Submersible Mixed Gas Dive Computer. This has in the program the
Reduced Gradient Bubble Model of Bruce Weinke, Ph.D. While we could go into this in a deeper way, let us defer that to another time. In another post, BillP give two links which can be read to gather some more information on these topics. They are not easy reading, however. Some information is also in Dr. Weinke's book
Basic Diving Physics and Applications (Best Publishing)
The RGBM is an outgrowth of the Variable Permeability Bubble Model of the late physicist David Yount, Ph.D., of the University of Hawaii. This VPM concept has relatively long-lasting gas bubbles stabilized by surfactant molecules at the interface of the gas (= bubble) and liquid tissue (= fluids). These bubbles have a certain defined lifetime and grow when in a supersaturated fluid, as during decompression.
The RGBM then takes the bubbles that are semi-stable and uses them in a way such that
some dissolved inert gas is not eliminated from the tissues but rather is sequestered in the bubbles, much like a squirrel storing nuts. Before the next dive, more time will then be required to eliminate the free gas, or to look at it another way, the gas in stored
in loco and the NDL is reduced for the next descent. Because some of the free gas is in the bubbles, the
pressure gradient for elimination is reduced (free gas is at ambient pressure + a small amount from surface tension. That is to say, the gradient is reduced, and hence the name for the model. {Dr. Weinke eschews fancy Greek words -- I would have made up something to give it an air of mysticism and called it the
hypocatarhesis (= "less reduced flow") model. } :bonk:
These concepts from ABYSMAL are built into their dive software and dive computers.
