Thoughts on Deep and Wreck Diving

[ageddiver]

Lavasurfer, I agree with at least one other poster and think you misunderstand when referring to experience vs. knowledge. I think that all of those divers you mentioned would tell you that it's experience AND knowledge that's so valuable and must be present in equal amounts. They're hardly reckless people - you'll find they dive the way they do from experience with others and watching accidents happen. I've been out with people who can cut tables in their heads, have the latest tools including computers, and who I wouldn't dive with because they have little if any experience with the conditions or depths. I'm better off diving solo, because their problem is my problem (and a big problem at those depths). A diver is equally dangerous if they don't continue to learn and adapt as the industry knowledge progresses - equipment too. John Chatterton now dives trimix with a rebreather and a completely different set of tables.

And none of these "old school" divers would do something as stupid as dive with no contingency plan in the event of some gas loss. The cowboys don't last too long below 200fsw.

 

[wedivebc]

This thread reeks of one of those "lets make fun of everyone who doesn't dive DIR(ish)"
All those name you mentioned yeah did things in the past that in todays diving community may not be the best methodology and some may still be doing it but remember, the names you mentioned have done dives that few have done, did it long before most of us were diving and did it before anyone had a fearless leader to act as a mouthpiece for our little collective and tell us exactly how to do it right.
Instead of looking down you nose at these pioneers of tech diving get off you high horse and remember you are where you are in diving because they did what they did.

 

[TheRedHead]

See Lamont's post above #16, and pp12-13 of AG's Ratio Deco/The Theoretical Aspects: http://www.5thd-x.com/xducation/pdf/ratiodeco.pdf

Oh, yes, I remember that document. I've read it several times and printed it out in the past. The stage bottle size is very clear. I assume you calculate the backgas as per traditional rock bottom? Are the assumptions the same? If you are say, diving at 170 feet, do you reserve enough gas to get you and your buddy from 170 feet to the gas switch deco stop while making your deep stops?

 

[lamont]

This thread reeks of one of those "lets make fun of everyone who doesn't dive DIR(ish)"
All those name you mentioned yeah did things in the past that in todays diving community may not be the best methodology and some may still be doing it but remember, the names you mentioned have done dives that few have done, did it long before most of us were diving and did it before anyone had a fearless leader to act as a mouthpiece for our little collective and tell us exactly how to do it right.
Instead of looking down you nose at these pioneers of tech diving get off you high horse and remember you are where you are in diving because they did what they did.

The flip side of that is reading (e.g. in Shadow Divers) that technical divers all view a buddy as a liability (there's a long passage in there laying it out like its the rule of gravity). I disagree. When it gets brought up like its a rule, I'll point out that I disagree with it... vehemently. There are two very well developed schools of thought on the issue, not just one.

 

[Kevrumbo]

Oh, yes, I remember that document. I've read it several times and printed it out in the past. The stage bottle size is very clear. I assume you calculate the backgas as per traditional rock bottom? Are the assumptions the same? If you are say, diving at 170 feet, do you reserve enough gas to get you and your buddy from 170 feet to the gas switch deco stop while making your deep stops?

Yes, but in this instance "Rock Bottom" is now called MGR (Minimum Gas Reserve --and still another acronym! ); reserving enough back gas to at least get you to your first gas switch. Actually as a proper contingency, you should plan MGR plus the loss of at least one of your Deco Bottles as per AG's Ratio Deco Article.

 

[TheRedHead]

I reread "Shadow Divers" recently and was amazed when Chatterton went OOG while retreiving the 2nd parts box and opted not to share air with Richie Kohler and made a dash for the deco bottles he had left near the entrance. I am not in any way trying to diminish his skills, but with a team approach, I think a successful air share would have resulted.

 

[wedivebc]

The flip side of that is reading (e.g. in Shadow Divers) that technical divers all view a buddy as a liability (there's a long passage in there laying it out like its the rule of gravity). I disagree. When it gets brought up like its a rule, I'll point out that I disagree with it... vehemently. There are two very well developed schools of thought on the issue, not just one.

I am a tech diver, obviously not DIR but I have certain buddies that I consider a definate assett. I will do dives with them that I wouldn't do with others or even solo because I trust their skills and knowledge. There are some divers I consider a liabilty (or potential) and I will dive with them as well (within limits). I will even dive with DIR if they are open minded enough to dive with a guy in a rebreather and not look for the shovel
I just feel this thread has a self-serving agenda.

 

[TheRedHead]

Yes, but in this instance "Rock Bottom" is now called MGR (Minimum Gas Reserve --and still another acronym! ); reserving enough back gas to at least get you to your first gas switch. Actually as a proper contingency, you should plan MGR plus the loss of at least one of your Deco Bottles as per AG's Ratio Deco Article.

I grok it now! I've been diving 1/3s and I don't even think about overheads. I'm a chicken-deco-diver. I think this method will work out to be less conservative than 1/3s on the type of diving I'm doing. Thanks!

 

[TSandM]

To get off the buddy vs. no buddy part of the OP's post -- the last part, about the driver not needing to know the details of the design of the car's engine, is very much along the lines of the extremely interesting DVD on Decompression Sickness that GUE put out earlier this year. I watched the entire thing, which is quite a series of interviews with experts in decompression research from Duke, and DAN, and others; the bottom line was that there is more we don't know about decompression than that we truly do know -- if by know, you mean understand at a real physiologic level.

People get heated in arguments about decompression software, decompression algorithms, decompression gases . . . But in fact, everything we are using is based on a variety of algorithms. They are not, as I read in an article today, actual "models", because mathematical models are based on measured parameters for systems. We really don't have many of the pertinent measurements. What we have is a theoretical CONSTRUCT for gas loading and unloading, which has led to table construction which is then empirically validated. That means that a certain level of DCS is deemed acceptable, and dives are done to validate that DCS does not occur more frequently than that.

Even I, with my rudimentary understanding of all this stuff, can balk at one of the underlying assumptions of a number of the "models", which is that gas loading and unloading occurs serially into the various compartments. A knowledge of physiology means that you understand that gas loads first into the bloodstream, but then more or less simultaneously into all other body structures. The only "model" I've read about that postulates a parallel system of gas loading is the DCIEM algorithm (which incidentally also has, if I understand things correctly, one of the largest empirical databases for validation).

So I guess what I'm trying to say is that people DO get overly obsessed with debating the fine details of a variety of systems, none of which is anywhere close to ideal. And the data are really not collected well from the technical dives, to evaluate the success or failure of the various systems.

 

[wedivebc]

. The only "model" I've read about that postulates a parallel system of gas loading is the DCIEM algorithm (which incidentally also has, if I understand things correctly, one of the largest empirical databases for validation).

.

Actually DCIEM is one of the few serial models. They assume one tissue affects adjacent tissure where neo-haldane models assume parallel loading.