deco mix & travel gas for hypoxic dives; thoughts

[Kern]

In my never ending quest to confirm/improve on what I'v been taught in my tech courses, I have a question on deco & travel gases used on hypoxic dives.

Travel gas; I'v seen some who use a separate travel gas no matter what else they have access too. Personally, I use my 1st deco gas as a travel gas. What do you do?

Deco gases; recently I thought I'd look around & see what others are doing for deco gases in the 70mt - 100mt range. I'v been using 21/35 & either 50% or 100% depending on availability & actual depth. I'v been thinking about using 30/30 & 100% for the deeper dives in this range. The IART manual I have access to, requires 32% & 80% for training dives to 90mt. For various reasons, IBCD foremost, I didn't like the sound of that very much. What do you use & why?

 

[fdog]

Re travel gas:

I breathe real, uncompressed air on the surface, and haul ass to 10'.


All the best, James

 

[ucfdiver]

Re travel gas:

I breathe real, uncompressed air on the surface, and haul ass to 10'.


All the best, James

Someone nearly killed themselves doing that at a large cave exploration project, when they got tangled on descent.

 

[fdog]

Okay. Since I'm not a caver, I'll take that prima facie.

In the open water diving I do, it would take a helluva entanglement, including handcuffs, to either prevent me from making it to a measly 10' deep in more than 2 minutes, or prevent me from deploying a 20' or 70' reg.

I'd rather not have the extra gas switch on the way down, or the hassle of an extra (dedicated) travel bottle to scooter with.


All the best, James

 

[Kern]

Each to their own, but I wouldn't consider breathing 12% O₂ on the surface. I don't find it too big a deal to swap regs on decent.

PS. Not a caver.

 

[Cave Diver]

Okay. Since I'm not a caver, I'll take that prima facie.

In the open water diving I do, it would take a helluva entanglement, including handcuffs, to either prevent me from making it to a measly 10' deep in more than 2 minutes, or prevent me from deploying a 20' or 70' reg.

I'd rather not have the extra gas switch on the way down, or the hassle of an extra (dedicated) travel bottle to scooter with.


All the best, James

I'm with James. I'm not doing anything deep enough in caves for travel gasses to be an issue. In OW, we're heading for the bottom, not dicking around at the surface.

Each to their own, but I wouldn't consider breathing 12% O₂ on the surface.

PS. Not a caver.

If I'm going that lean, I'd probably opt to do the same as you and start on deco gas them make the switch on descent.

 

[fdog]

Each to their own, but I wouldn't consider breathing 12% O₂ on the surface. I don't find it too big a deal to swap regs on decent.

PS. Not a caver.

Woof! ...12/60... (not that I've ever used it) for that, I'd probably use 50%, too, as a travel gas.


All the best, James

 

[Kern]

Don't use it very often myself. 12/60, 15/55 on OC, are very expensive dives down here.

 

[w ripley]

There are too many unknowns in that first 10 to 15 feet as you jump off a boat, for example, for me to have anything hypoxic in my mouth.

I remember times when it was all I could do was to hang on because of the current, issues with getting air out of my drysuit or wings, ear equilization problems, etc., that prevented me from getting to the depth needed for an hypoxic mix. Personally, I'd rather be free to focus on the unexpected issues that might come up than to be forced to get to a depth where I can take my first breath.

I know plenty of divers who have no issues with hypoxic mixes on the surface, but you have to dive the way it makes sense for you. I'm not jumping in with a buddy who can't breathe what's in his mouth. I've got too much to do to take care of myself in the first minutes of a deep dive to be worring about anyone else. I'm there is needed, but would rather be focusing on making sure I'm OK.

If dives were always ideal, in wave-less oceans, with no current and no gear issues, then I might feel differently. But we're trained - and have learned over years of diving - that ideal is seldom the case. We prepare for every adverse senario we can imagine; Why do something that sets you up for a potential disaster from the get-go when there are so many other ways to safely accomplish the same end?

 

[rjack321]

I'm not using travel mixes for mildly hypoxic gases like 15/55.

For even deeper dives (12/65 or less that I'm not doing around her cause its too damn cold) I would almost for sure have a 3rd deco gas along which I would use before EAN50 if it was absolutely required. But even 12/65 I'd probably just deal with the surface on the surface breathing air, then pop the reg in and drop. We don't screw around at ~8ft, we hit the trigger and go down down.

Someone nearly killed themselves doing that at a large cave exploration project, when they got tangled on descent.

On SCR with a ~20% ppO2 drop = something like 8/70.