Advanced decompression theory

[loosebits]

Another thread got me thinking about this. I took my adv nitrox along with full cave. The instructor was great and I have no complaints about his teaching ability. It was the material that I take issue with.

For one thing, the material revisited all the same stuff we learned in OW and in nitrox: signs and symptoms of DCS, OTU/CNS calculations, EAD calcs, MODs, blah blah blah.

The only thing I learned in adv nitrox that I either didn't already know or wasn't covered in full cave was how to shoot a bag... seemed like a really expensive class to learn how to shoot a bag.

Can I ever look forward to a class such as trimix covering more advanced topics such as the theories behind bubble models, the origin of the oxygen window and other topics that would allow a dvier to critically compare RGBM, VPM-B, VPM-B/E and Buhlmann's ZHL-16? I've read through all the documents I can find on the topics but I would love to have the opportunity to discuss it with an expert.

Finally, is my entry level mix class going to be another big disappointment (END, EADD, basic understanding of IBCD, He fast, N2 slow, etc)?

 

[chrisch]

To be honest there isn't much about deco models in any "regular" courses that I know of. Its a subject in its own right and if you read about it and keep up to date with all the latest stuff you will often know more than many instructors.

Diving courses are there to teach you diving. Technique is important and the theory side is there for you to make sense of the technique. IE why its important to hold a stop accurately etc.

Trimix theory covers the use of helium in the breathing gas. All previous courses will have been about nitrox mixes (inc 21% in your OW).

Don't expect too much about comparing deco models, bubble theory or other such topics unless your instructor has an interest in that area. The idea is to get you diving safely with a new gas.

Chris

 

[loosebits]

That's what I was afraid of. As I thoroghly understand the consequences of helium in my breathing gas, probably more so than would be covered in a mix class, such a class would amount to another buy-a-card class... and an expensive one at that.

Does anyone know of an instructor in either Texas or Florida that can discuss more advanced topics once they are convinced that you can calculate the END, EADD, etc?

 

[boydski]

Can I ever look forward to a class such as trimix covering more advanced topics such as the theories behind bubble models, the origin of the oxygen window and other topics that would allow a dvier to critically compare RGBM, VPM-B, VPM-B/E and Buhlmann's ZHL-16? I've read through all the documents I can find on the topics but I would love to have the opportunity to discuss it with an expert.

Finally, is my entry level mix class going to be another big disappointment (END, EADD, basic understanding of IBCD, He fast, N2 slow, etc)?

Hi loosebits,

I think a lot of this depends on the instructor and the level of interest. I was very fortunate to take my Trimix class with an Old-school Trimix Instructor Trainer, and a new instructor (his first class) that had an interest in this. He passed out several excellent technical articles on different gas models, and we did discuss the differences between the Buhlman models preferred by the Instructor Trainer and the Bubble Models preferred by the instructor. However, when we started talking about Oxygen Windows, you could see the eyes glaze over on the other students in the class.

I think the most important thing that came out of our discussions were a reminder that it is all just a theory to try to model observed behavior. We don't really know what is happening on a physical level, but try to aproximate what we think is happening using mathematical models. Comparing profiles for different models is a good excercise, and many can be adjusted to get very similar profiles for moderate dives.

My old-school trainer said, "what works, works". Meaning if you get out of the water feeling like "Butt", you're coming up too fast.

Good luck,

 

[PerroneFord]

Does anyone know of an instructor in either Texas or Florida that can discuss more advanced topics once they are convinced that you can calculate the END, EADD, etc?

Yes.

In fact, as I sat through one of his rebreather classes a few months ago, the author of the Nautilus decompression software was in the class. We had a VERY lively discussion on deco theory and practical application.

I was also in class with the programmer for GUE's DecoPlanner software, but we had little spare time to discuss deco theory. I did get to spend time after that class talking to a doctor of Hyperbaric Medicine about deco theory and application as he works with it daily at NEDU.

I'm always amazed at who you can run into and speak with when you get out in the community and surround yourself with the right people. I feel very fortunate.

 

[loosebits]

Ok, what is the name of such an instructor?

 

[PerroneFord]

Ok, what is the name of such an instructor?

Rebreather class instructor was Gregg Stanton. Other class was with Jarrod Jablonski. Both good classes, and good instructors. In my opinion of course...

 

[loosebits]

I've always thought you Floridians had it lucky. Here in Texas, there is probably only a handful of real trimix instructors (and most of them probably came from FL or New England). Everyone else is likely a Johnny-come-lately.

I wonder what it takes to become a mix intructor through TDI, IANTD or PADI (do they offer mix yet). At this level, I think we should be demanding more of the training agencies. I've read the TDI mix book... not a single topic in it that any OW student that paid attention couldn't figure out on their own in 20 minutes (provided you tell them that He is a fast gas and is 23% as narcotic as N2/O2).

I wonder what was covered when that second generation of divers learned mix from the pioneers and at what point was it considered too much information to go over in a $500 class.

 

[PerroneFord]

If you have interest in taking some courses, let me know. There are some good instructors around here who can give you the real deal.

 

[limeyx]

I've always thought you Floridians had it lucky. Here in Texas, there is probably only a handful of real trimix instructors (and most of them probably came from FL or New England). Everyone else is likely a Johnny-come-lately.

I wonder what it takes to become a mix intructor through TDI, IANTD or PADI (do they offer mix yet). At this level, I think we should be demanding more of the training agencies. I've read the TDI mix book... not a single topic in it that any OW student that paid attention couldn't figure out on their own in 20 minutes (provided you tell them that He is a fast gas and is 23% as narcotic as N2/O2).

I wonder what was covered when that second generation of divers learned mix from the pioneers and at what point was it considered too much information to go over in a $500 class.

GUE instructors are always willing to travel to different locations to teach classes

Decompression is covered pretty well in Tech1, a lot of history of different theories is covered as well as GUE's approach to decompression. However, it's all taught in something of a compressed timeframe so it helps to have done some reading beforehand and have some questions prepared.

In our case we were given links to some other articles (M-values, CO2 retention etc.) to read before the class to help us get familiar and form some of our own questions.

However, this is just the beginning of it -- you can't possibly cover everything in a class, no matter how comprehensive, and a lot of it has to be tailored to each indivdual diver, so it really ends up just being a starting point to work with and refine.