Doubles configuration

[DIR-Atlanta]

SO is Argon used on the wing or just for the dry suit (when used?)

Just on the drysuit, and also to inflate an SMB if you use one.

I may try to swing by for the gear config night. Let me know. Most of next week I will be in Southern California. Of course my doubles won't be ready until next week (Monday at the earliest) anyway. Will you be doing the webbing/backplate or just doubles and regulator setups?

You're also more than welcome to stop by one of our monthly DIR-Atlanta meetings, or sign onto our Yahoo E-mail list. We'll be more than happy to answer any questions you have, or even do a dive with you some time to help you sort things out. Send me a PM if you are interested in that.

 

[jonnythan]

Argon is just used for the drysuit. There is a great debate about whether it's actually more insulating than air and nitrox, but there is a consensus that it's much more insulating than trimix. Trimix contains helium, which conducts heat very well and is a poor insulator, so this is the major impetus for argon use.

 

[rjack321]

Why? So both of you can be exposed to more risk? You isolate, you thumb, no if's or buts.

If you've been diving a conservative gas management plan you have enough gas to exit without going on your buddies long hose. Obviously you place the distress diver in the best position for the team and "close ranks". Going to your buddies long hose when you still have gas truly makes egress more difficult and places more divers at risk.

By the right tank for buoyancy I assume you are talking about the reg on the right post has the LP inflator hose coming off it. Only when wet would that be your only bouyancy, left post of argon bottle supply the drysuit.

Let's say I'm in a cave or wreck. Burst disk fails on the left. Isolated doubles. Unknown quantity on the right.

Do I share gas with my (let's say one) buddy or not? Like right now?

I say share now. You have some amount that may or may not get you out and to the surface in that right tank. E.g. failure at 1/3rd into a cave and you definately don't have enough since you might only have 1/2 or less of the right tank remaining - not 2/3rds. Some amount was lost.

The way Murphy works, that right tank will run out at a bad time, like when you are single file and can't turn around to ask for gas easily. Or on ascent when you are trying to hold the 70ft stop and some of the gas went in but then you didn't realize it ran out and you're dropping.

Yes sharing gas will slow you down a touch, but after the first couple minutes you should hit a groove and move at a good clip. Save the right tank's remaining gas for awhile for:
1) bouyancy (in your wing not DS), and
2) in case you need to or its dramatically faster/easier to breath you own tank for a short while.

E.g. On a tech dive you might consider sharing on the bottom but going back onto your own right post for ascent and you can both better control bouyancy vs. having an OOA midway up.

In a cave you might share for a few minutes maybe until you get to a narrowing (like the lips - based on what I've heard) then go back to your right tank for the constriction(s) or once back in the cavern zone.

I would not remain on the right tank for the entire exit/ascent of that dive. But I wouldn't necessarily share the whole way either.

That's how I would manage this failure, YMMV

 

[KMD]

Just on the drysuit, and also to inflate an SMB if you use one.

If you are using an argon bottle. Do you leave your normal drysuit inflator attached to your regs or do you remove it?

I ask because I tuck mine behind my wing and it stays there, but if I want it for some reason I just have to reach down to the bottom of my tanks (it sticks out about 6 inches) and pull it loose.

 

[rjack321]

If you are using an argon bottle. Do you leave your normal drysuit inflator attached to your regs or do you remove it?

I ask because I tuck mine behind my wing and it stays there, but if I want it for some reason I just have to reach down to the bottom of my tanks (it sticks out about 6 inches) and pull it loose.

Personally I have not used backgas inflation of double in a year or more. But then again I get argon for cheap at home.

Are you diving nitrox mixes in doubles most of the time? If you are diving He, I'd remove it, its not useful.

 

[DIR-Atlanta]

If you are using an argon bottle. Do you leave your normal drysuit inflator attached to your regs or do you remove it?

I don't. I have two identical backup regs - one with a drysuit inflator hose, and one without. I use the one "without" when diving doubles wet, or diving dry with argon (which is actually most of my diving in doubles these days). The one "with" is used on the rare occasion that I inflate the suit with backgas. It also serves as a backup to the first one.

 

[mikerault]

Ok, why not have a small SPG on the backup regulator primary? I realize it is an extra hose but wouldn't it provide redundancy and eliminate the "How much gas do I have?" worry if the unthinkable happens? Hmmm...might be a place where that dreaded air integrated dive computer might be handy...

Mike

 

[rjack321]

This is the DIR forum and the DIR answer is we don't use a second spg on the right post.

Reason 1: there is always enough gas to return to you and your buddy to either the surface or your next breathable gas (eg a deco bottle) Its the rock bottom in your buddies tanks.

Reason 2: its another failure point

Reason 3: If you isolate and now know you have insufficient gas to get out it doesn't do much for you. If you have isolated and nw know you have insufficient gas so what - see #1.

Reason 4: If the isolator is inadvertently closed you will know it when the left spg doesn't move like its supposed to.

There's really no need or benefit for 2 spgs in the DIR universe.

 

[Kendall Raine]

Ok, why not have a small SPG on the backup regulator primary? I realize it is an extra hose but wouldn't it provide redundancy and eliminate the "How much gas do I have?" worry if the unthinkable happens? Hmmm...might be a place where that dreaded air integrated dive computer might be handy...

Mike

If you lose the left post and spg the dive is over. You're leaving. You've either left enough gas to get out through rule of thirds and quick shut down or you haven't. Knowing won't matter. It is what it is. If you totally blew the shut down and don't have enough gas, you have a buddy to borrow from. Your buddy should have more gas than you-enough to get you both out from the farthest point of penetration-since you were both diving thirds, matched your turn points, and presumably the buddy has not sustained a simultaneous failure. If you both sustain a simultaneous failure and can't respond adequately so that you have sufficient gas to exit, then you won't need a redundant spg to tell you you're both dead. That's why all the rules are part of an integrated whole and make sense in that context. Taking them out of context is just that. That's also why you practice your shut down drills everytime you go diving.

 

[jonnythan]

It's another piece of gear to maintain, use, store, and, most importantly, fail.

It serves no functional purpose whatsoever. The SPG is already a backup for your head. There is no need for a backup for the backup of a piece of gear that ceases to matter once you begin your egress anyway.

Having extra, unnecessary equipment that doesn't serve any real purpose goes directly against the principles of DIR and hogarthian diving in general.