Recreational Trimix

[waterpirate]

30/30 is a gue standard gas. gue responses are to be expected IMO

This is what I was implying in my response. That the choice of 30/30 on this profile, even if it were left over mix is a "standard gas". That being the case I was curious how someone could be gue familiar or affiliated and not understand the consequences/ implications of their choice of gases for a given profile. One step further got me to how you get 30/30 mix in a set of doubles and do not understand the choice at any given depth, regardless of the "secret handshake" or not.
Eric

 

[lamont]

OTOH, I can point to mixed teams with 21/35 and 21% where the 21% diver has been bent. I'm very unconvinced that helium necessarily penalizes decompression.

I think that is very dangerous advice. 30% He is too much to be ignored, or treated like nitrogen. Ask anyone who has suffered from a He bend if you can just blow off 30% He in a mixture. YMMV.

For the OP, I learned the same lesson on the Vandenberg last year. I had a bunch of 18/45 in my doubles I wanted to get rid of. I'd have spent a lot less time on deco diving air...

 

[Wookie]

OTOH, I can point to mixed teams with 21/35 and 21% where the 21% diver has been bent. I'm very unconvinced that helium necessarily penalizes decompression.

Air is for putting in your tires, mix is for breathing...

 

[Kevrumbo]

I did a recreational double dip on the Spiegel Grove today. Decided to use my doubles which were already loaded up with 30/30. Figured displacing all that evil nitrogen with heavenly helium would give me nice, long no decompression limits. Did that ever turn out to be a stupid move!

As it turns out, 30% NITROX would have yielded a NDL of 26 minutes at 100' vs. 14 minutes on the relatively pricy trimix. My "stoke" buddies got a 28 minute NDL on their 32% Nitrox and I ended up doing a lot of deco time on my fancy back gas.

I'm fully aware that the primary benefit of increased helium percentages is reduced narcosis as opposed to increased NDL bottom time. However, I was shocked to discover that more helium actually dramatically reduced NDL limits all other things being held constant.

Can someone please explain this to me?

http://www.scubaboard.com/forums/ask-dr-decompression/32090-helium-offgassing-rate-2.html

Getting back on track from the hijack above, and with better practical advice --recommend that the OP take Oxygen next time for a final & more efficient clean-up rather than deco'ing out on backgas 30/30 triox alone. (Take an additional Adv Nitrox/Deco Procedures Cert Class if you don't already have the training. . .)

 

[GShockey]

This is what I was implying in my response. That the choice of 30/30 on this profile, even if it were left over mix is a "standard gas". That being the case I was curious how someone could be gue familiar or affiliated and not understand the consequences/ implications of their choice of gases for a given profile. One step further got me to how you get 30/30 mix in a set of doubles and do not understand the choice at any given depth, regardless of the "secret handshake" or not.
Eric

There is a problem with picking and choosing from various GUE practises (eg: in this case standardized gases) in that our philosophy was never intended to be offered as a buffet where you could skip particular food groups and concentrate on the desserts... It is an a' la carte meal that covers all the basic food groups without skipping any nutrients. (just sitting down to dinner, hence the food metaphors...) While some components of our training are just good diver skills (buoyancy, trim, propulsion...) others are part of a larger picture where they are not intended to be taken in isolation from each other. (Minimum deco, ascent rates, standard gases). While picking from the buffet may ward off starvation, it doesn't necessarily guarantee you won't be malnourished....

 

[deepstops]

I knew it wasn't a DIR scenario as soon as he said he was diving 30/30 and his buddies dove 32. If they were diving DIR, they would have all been diving the same mix

 

[waterpirate]

Agree with the buffet analogy 100% You either embrace the "whole enchilada" or not. My real questions and thought stem from how somone could dive 30/30 and not understand the consequences of that choice prior to execution? Secondly the querry should have been discussed to death in he 101 even if it were techreational triox. Only explanation is that this was a computer dive with no plan prior to splash, that would prompt this whole line of questions from the op post dive on the boat with the buddies diving 32%.
The concept of people diving different models on the same gas at different gradients or safety factors should also have been addressed at some point by instructor/mentor. There was obviously a disconnect somewhere'
Eric

 

[waterpirate]

There is a problem with picking and choosing from various GUE practises (eg: in this case standardized gases) in that our philosophy was never intended to be offered as a buffet where you could skip particular food groups and concentrate on the desserts... It is an a' la carte meal that covers all the basic food groups without skipping any nutrients. (just sitting down to dinner, hence the food metaphors...) While some components of our training are just good diver skills (buoyancy, trim, propulsion...) others are part of a larger picture where they are not intended to be taken in isolation from each other. (Minimum deco, ascent rates, standard gases). While picking from the buffet may ward off starvation, it doesn't necessarily guarantee you won't be malnourished....

Is it O.K. to just have the cookies and juice before naptime? I really like them!

I was gue curious in college, but just that one time. I smoked gue but never inhaled.

I am interested in all types of diving and all aproaches to the task at hand. Somehow that all gets boiled down into what I feel is safe practice. In conjunction with training at higher levels beyond advnitrox/deco proced it becomes ones own aproach. Personally I feel like the darkside aproach is to rigid for the type of diving I do. That being said if I were to ever move on to extended range either deeeeep or miles up a cave, the team aproach would certainly be the choice I would make.
Eric

 

[LiteHedded]

I knew it wasn't a DIR scenario as soon as he said he was diving 30/30 and his buddies dove 32. If they were diving DIR, they would have all been diving the same mix

meh...

 

[kanonfodr]

I was gue curious in college, but just that one time. I smoked gue but never inhaled.

GUE doesn't condone smoking, that's why we just drink it now .

Peace,
Greg