Deco Gases

[HolgerS]

@ Triton

Trust and credibility is a serious issue. I absolute agree. I personally don´t believe in this conventional He-parameters due to the fact, several divers prove in their day by day dives these are too conservative. But as you said - everyone need to have confidence in what he/she is applying.

But please read my first posting. I gave three arguments. The very first one is a very obvious. The other ones are much more subtle.

Regards
Holger

 

[rossh]

The latest release of V-Planner addresses this "fast helium" deco concept. I have named it "Accelerated Stops". (see the configuration options).

How does it work?
The procedure allows / forces an increased off-gassing gradient temporarily during the last few stops of a gas mix, but in a controlled manner. The end result is shorter overall run times due to some of the slower deco time being “accelerated.” It is the combination of accelerating a low ppO2 stop and extending a high ppO2 stop along with helium based deco that makes this manipulation of stop times possible.

Up until now, deco programs would not let the diver intentionally violate a deco ceiling like this. Some in the diving community therefore assumed that deco programs failed to handle helium correctly. A deco model properly configured to handle this skip-ahead procedure, can handle helium decompression as desired.

A most interesting aspect of this: Existing model parameters and constants for He are used, and provide the desired results to satisfy the "fast helium" proponents.

Regards

Ross Hemingway
http://www.v-planner.com

 

[jagfish]

Thanks for addressing that point, Ross...

 

[triton94949]

Thanks Ross. I did not mean to put your software program on the spot. Thanks also for the new options on the software update release.

 

[lamont]

If I'm reading you right, accellerated stops work when you're switching from 50/50 to O2, but if you didn't have the O2 in there you wouldn't see any difference from the 50/50?

Does anyone use 50/50 as a single deco gas instead of EAN50, or is it only used when also using O2 at 20'?

 

[HolgerS]

@ lamont

I don´t use heliox 50/50 as deco gas, just He "enriched" gas like 50/25. I always combine O2 together with 50/25.

There is one excemption. When diving with 21/35 or 18/54 and just one deco gas, I sometimes use 50/15 instead of EAN 50. Reason is mentioned above. I don´t change deco schedule. The last 6m I always ascent with 1m/min.

Greetings
Holger

 

[rossh]

If I'm reading you right, accellerated stops work when you're switching from 50/50 to O2, but if you didn't have the O2 in there you wouldn't see any difference from the 50/50?

Lamont, It will do more than that. The bottom mix can be accelerated into the the first deco gas switch, along with all other subsequent mix changes. You can control these individually, if desired.

There are however, tests to verify sufficient helium in the mixes (25% +) and it does require O2 to finish off the dive.

Regards
Ross Hemingway
http://www.v-planner.com

 

[triton94949]

@ Triton

Trust and credibility is a serious issue. I absolute agree. I personally don´t believe in this conventional He-parameters due to the fact, several divers prove in their day by day dives these are too conservative. But as you said - everyone need to have confidence in what he/she is applying.

But please read my first posting. I gave three arguments. The very first one is a very obvious. The other ones are much more subtle.

Regards
Holger

Holger I believe that if you will invest about EU 100 in the latest V-Planner software and select the accelerated helium deco option, that would give you a chance to fine tune your own mixes and combinations.

I have found that for my own diving, I get the best results with either TMX 10/70 or TMX 15/60 together with deco mixes of TMX 20/40, TMX 30/30, EAN 50, and 100% O2.

You can still go back to your deco on the fly, after you run the software comparisons. But deco on the fly won't teach you what works best in various combinations. For that you need to rely on someone else's complex algorithm, at least if you believe in mathematics as much as you believe in physics.

And nobody has done a better job on any deco software than Ross has. (My opinion, of course.)

Another major reason why I prefer to stick with EAN 50 rather than TMX 50/25 is Ross' caveat that with TMX 50/25 etc you must finish your deco with 100% O2.

I prefer to have my EAN 50 bottle backup my 100% O2 bottle in case the latter fails. Sometimes I only have two deco bottles with me (never less than two however), and in that case swapping regs underwater might become precarious or worse.

The beauty of Ross' deco software is that it also allows you quickly to calculate alternative deco plans, in case Bottle #1, #2, #3, or #4 fails during your deco. I normally put those all on my wrist slate, then memorize them all before the dive.

You could always buddy breathe with your buddy's deco bottle, assuming he made it back with you (buddies do strange things and sometimes disappear), but that might become precarious as well. I have never known anyone who does deco on the fly also to mount two second stages on a deco bottle, in case deco mix sharing became necessary, although you might consider that as well.

Those are some of the practical issues for not mixing HE in your 50% deco mix.

I have no use for the accelerated helium deco option, personally. But you might like it.

 

[boomx5]

I have found that for my own diving, I get the best results with either TMX 10/70 or TMX 15/60 together with deco mixes of TMX 20/40, TMX 30/30, EAN 50, and 100% O2.

It's obvious Holger is GUE trained and therefore uses GUE standard mixes. The different gases that you mention here are pretty close to the GUE standard mixes and would work well with ratio deco. I also agree that Ross has a fine piece of software and produces a nicer profile than Deco-Planner...IMHO.

 

[triton94949]

It's obvious Holger is GUE trained and therefore uses GUE standard mixes. The different gases that you mention here are pretty close to the GUE standard mixes and would work well with ratio deco. I also agree that Ross has a fine piece of software and produces a nicer profile than Deco-Planner...IMHO.

This is not the dir forum. So I was not assuming that. I dont know how much flexibility his dive buddies give him. What you choose always depends on your buddies. It is always best if you can all agree on the same mixes.