Best Mix VS Standard Gasses (split from a GUE fundies course report)

[CptTightPants21]

Exactly! Stop trying to think for yourself and do what we said in that table of gases!

What? Your experience has lead you to feel like you are unusually prone to narcosis, so you would only want to do a 150' dive using TX21/55? Sorry. Not supported. Tough potatoes. Enjoy diving solo, 'cause none of us will use that gas, therefore we won't do that dive with you.

I have completely lost what you are even talking about at this point? First it's helium is too much, now you are arguing to use more helium than would be prescribed? How does this diver go from using air at 130' to needing 55% helium. Why are we completely bypassing 21/35 and 18/45? You talk about THINKING for yourself, what are you thinking with 21/55? The FO2 is too low for it to be best gas. What END are YOU diving? You are doing matrix style cart wheels and backflips to attack something that this very well thought out in an effort to declare 'I will dive any mix i feel like on any dive just because'.

You have told those two GUE stories before. GUE instructors have a lot more regulations on them than normal divers and instructors from other agencies (they can't solo dive, smoke, etc). He wasn't the first guy to bring the wrong mix on a dive boat and he won't be be the last guy. And the other guy, an a55hole who ignores all emails and then tries to come in at the last hour and change all the already agreed upon dive plans--yeah, I'm not surprised he was kicked out. I also don't know what that has to do with GUE specifically. Although, ironically enough, if he had been diving with an all GUE group he (or anyone else) could have jumped in at the last minute and all the gases and ascent strategies would have already been known. Standardization...it's a55h0le proof.

 

[ChuckP]

I’m looking for the standard dive site lmao......

Out of curiosity, is there a standard GF? Tough to team dive if we are all on a different schedule so I assume there is one.

How’s that work for 80 degree drifts verses 40 degree working in the current?

 

[helodriver87]

20/85 is the standard currently. You'll see teams coordinate different ones on occasion. I'm actually hoping to see that change to a much higher GF Low.

 

[CptTightPants21]

20/85 is the standard currently. You'll see teams coordinate different ones on occasion. I'm actually hoping to see that change to a much higher GF Low.

Agreed. Although that and the modified deco planner approach of evening out the intermediate stops captures a whole swath of GF combinationa. In Tech 1, I was clearing the 50/80 I had on my computer with the Modified DP generated with 20/85 and was one of the factors that sold me on the modified DP approach.

 

[PfcAJ]

20/85 is the standard currently.

Ew.

 

[1atm]

Well ... in the rec range and T1 range it does not really make a meaningful difference. I’d hazard the guess that a) there aren’t that many divers that regularly do T2 or T2+/T3 dives, and b) those that do, have sufficient experience of their own to choose a reasonable number within their team ...

In other words, while the GF discussion is interesting and important, the real life impact (at least for me) is negligible

 

[PfcAJ]

For what its worth, there are RARE occasions where using a standard gas has some drawbacks and a dive MIGHT warrant the use of something else.

Few and far between, though.

And certainly not because "helium is expensive"...

 

[LiteHedded]

explain what you mean? what is the scenario and what gas might you choose for what benefit?

 

[PfcAJ]

explain what you mean? what is the scenario and what gas might you choose for what benefit?

Maybe a very long dive at an intermediate depth. One particular cave like this has an avg depth of like 100ft, max 130, but also has extended shallow bits in the 60ft range. 30/30 isn't right, but neither is 21/35 due to the shallow bits and the RB80 po2 drop.

Few and far between are these examples.

 

[rjack321]

Well ... in the rec range and T1 range it does not really make a meaningful difference. I’d hazard the guess that a) there aren’t that many divers that regularly do T2 or T2+/T3 dives, and b) those that do, have sufficient experience of their own to choose a reasonable number within their team ...

In other words, while the GF discussion is interesting and important, the real life impact (at least for me) is negligible

That's about right. In the T1 range it doesn't make any difference and in the 150-200 range for shorter wreck dives (25mins BT) it's still basically a wash regardless of what GFs you choose (like 3-5 mins total over the ascent).

Getting deeper and/or longer and most of us: 1) talk about what we are doing and why 2) negotiate how we're going to run the deco. You should do that anyway - it just gets more & more important at 240' or 3hrs BT. And honestly most of us just end up hanging for the more conservative person to clear and its not a big deal.