Thoughts on Deep and Wreck Diving

[TSandM]

I'm going to go look that up -- I was pretty sure I had that right, because I remember it striking me the first time I ever read about the algorithms underlying the tables.

 

[Kevrumbo]

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!

RH, don't forget to figure in for your Buddy too!
Remember this is new & improved 21st Century "Paradigm Shift" Diving (notice I didn't use that naughty three-letter acronym to respect other's sensitivities ), and not the Old School, sololito macho, Dog-Eat-Dog, Northeast Wreck Diver Mentality & Practice.

 

[wedivebc]

I'm going to go look that up -- I was pretty sure I had that right, because I remember it striking me the first time I ever read about the algorithms underlying the tables.

In a parallel model, the tissue compartments are assumed to ongas and offgas to the blood stream independently of each other. No gas transfer is assumed between different tissues. Most dive tables are based on parallel decompression models.
The DCIEM tables are based on a four compartment serial model. Serial decompression models assume that gas transfers from tissue to tissue during a dive. Only one tissue is assumed to be exposed to ambient pressure.
In a serial model, the compartments outgas to each other even as they ongas from other tissues of higher nitrogen tension. These compartments do not use set halftimes. Different filling times result for each compartment depending on depth and time.

P(0) -> P(1) -> P(2)-> P(3)-> P(4)
P(0): Ambient pressure (In initial dive, P(0) = Atmospheric pressure)
P(1) - P(4): Nitrogen pressure in compartment

 

[PerroneFord]

Actually DCIEM is one of the few serial models.

Correct.

 

[JeffG]

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.

There is something wrong in translation I believe. There were 3 divers waiting outside when John came out.

There might be a bit of dramatic license being done here.

 

[JeffG]

This thread reeks of one of those "lets make fun of everyone who doesn't dive DIR(ish)"

Should it be any other way

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.

We cannot breath water. Team diving (DIRish) is one solution. Solo diving is another. OC is another tangent, where CCR is another.

All have their strengths and weaknesses. A diver just needs to make a call on what risks/limitations they are willing to accept.

 

[JeffG]

Serial decompression models assume that gas transfers from tissue to tissue during a dive. Only one tissue is assumed to be exposed to ambient pressure.

Might be a good model for fat.

 

[wedivebc]

Might be a good model for fat.

:lol: Yeah I have my own personal decompression algorithm

 

[JeffG]

:lol: Yeah I have my own personal decompression algorithm

No comment

 

[grazie42]

With regards to solo vs buddy in techdiving. Once you go deep enough or penetrate far enough, trying to rescue someone means that you become another victim. To make a rescue feasible on those kinds of dives would require an "unreal" amount of gas. AFAIK even "DIR gods" do those kinds of dives that way. For the "garden variety techdive" (the only kind I do) I think most (if not all) plan for getting your buddy back to the surface in the event of catastrophical failiure at the furthest point of penetration...**** can still happen and I think "selfsufficiency first" is almost a universal goal regardless of "discipline" here as well, the only difference is in the "cut-off point"...

Regardless of where your personal "cut-off point" is, make sure that whoever you´re diving with knows where it is so they can make an informed decision about whether to dive with you or not. IMO this is something you´d better spend some time thinking about and deciding (for yourself) before you even think about hitting the water with someone. Those are the kind of decisions I´d hate to make in a split-second at depth because if you´re lucky you´ll have a lifetimes worth of second-guessing to do afterwards...

With regards to decompression. Some people feel confident enough to "model the model". Others "tweak" the model of their choice based on experience/preference. Still others follow their decompression model religiously "out of the box". Personally I don´t see much of a difference if your model is found on the comp on your arm, in a pc or in a binder from someone you "trust". It´s all personal preference and "best guesses"...except when it´s not