Deco tanks left and right v All left

[catalina_mike]

Dito "On closed circuit I put mixed gas on the left and rich gas on the right." Dil on the left or lean mix... O2 and high octane on the right.

 

[PfcAJ]

What do you "lean left rich right" guys do when you have a 3rd deco gas?

 

[Dr. Lecter]

What do you "lean left rich right" guys do when you have a 3rd deco gas?

For me, it's something like bottom mix and 21% left, 50%/100% on the right for CCR B.O., with the richer mixes on either side being on the bottom. Did the same thing when I was diving 3 or more slung tanks on OC…the less you want to accidentally switch to it at 300', the more you want it on the right side.

That being said, I think it's more about balancing the number of tanks on any one side for ease of trim, management, etc. I'm not really a convert away from the idea that the main gas switching safety protocol is looking at and physically confirming the 2nd/hose/reg/tank before sticking it in your face.

 

[mathauck0814]

What do you "lean left rich right" guys do when you have a 3rd deco gas?

I stack O2 and Nitrox in the order they'll be breathed when bailed out on the right and gases containing helium in the order they'll be breathed on the left. If I need more than 4 gases (e.g., 5xAL80 dives) I'll nose clip to the left waist. I don't have a site or an occasion to dive more than that normally, but we're looking at some targets that would be much deeper; for those we're getting into experimenting with bailout rebreathers as the logistics are just too much for OC bailout.

 

[PfcAJ]

the less you want to accidentally switch to it at 300', the more you want it on the right side.

I have not experienced that same concern.

 

[Dr. Lecter]

I have not experienced that same concern.

No, you've experienced the exact same concern and dealt with it another way. But strangely enough, the human error rate for gas switching hasn't been 100% eliminated by any one approach of which I'm aware. I think you and I would probably agree that the first and best thing anyone can do is develop a switching protocol and stick to it as religiously as possible.

However, I believe it's wise to hedge one's bets against things not going as they should; if I somehow go to my BO in an absolute panic and/or distracted hurry, I'd rather have the instinctual side involve Russian roulette between, say, 10/50 and 21% and not something much worse. Do I plan or expect for that to be an issue? Of course not. But I do try to be agnostic about my own infallibility when it comes to planning, even if that involves some suspension of disbelief on my part.

On the other side of the coin, I also don't have any reason to stack all my bottles on the left side: I don't have a long hose anymore; even when I did have a long hose I was a solo diver and didn't plan to donate on a long, deep dive; and I've never needed a clean side for high-thrust DPV exhaust because I dive wrecks not caves and have isolation valves on all my bottles to boot. In fact, I have some good reasons not to try and stack 3-4 bottles on one side or use a leash: it's easier to don and manage bottles when there aren't more than 2 on a side; and, I find it easier to trim out that way rather than having a stack of bottles on one side and nothing on the other.

At the end of the day, you and I are doing very different dives. Doing OC cave dives with a buddy/team would involve a different balancing of costs and benefits from doing deep ocean CCR dives with a small team of solo divers, so it's not surprising (to me, at least) that people come out at different approaches. What still surprises me is the institutional idiocy of agencies, instructors, and kool-aid drinkers who truly believe that there's a Swiss army knife of standardized kit and skills that is not only workable for all dives, but optimal for all dives. But that’s another thread

 

[mathauck0814]

No, you've experienced the exact same concern and dealt with it another way. But strangely enough, the human error rate for gas switching hasn't been 100% eliminated by any one approach of which I'm aware. I think you and I would probably agree that the first and best thing anyone can do is develop a switching protocol and stick to it as religiously as possible.

There's an equipment solution ("failsafe") to a mental mistake problem that our team employs that serves two purposes. Having in-line shutdown valves on your deco/bailout second stages which are engaged on all but your bottom bailout means that a) if you grab the wrong gas at depth, you just won't get anything and b) you're unlikely to accidentally freeflow a bottle while scootering.

I like it as an insurance measure. YMMV

 

[tom_n_tacoma]

I carry on the left in the order that you breath them. Then I took a class from a different instructor who insisted on 02 on the right and the other deco on the left, I gave up the argument and did it for the class. Then after back to both on the left. Why? That's how I was first taught, that you had a free arm, no obstructions for the long hose and easier for scooters. Do what ever the team of folks you dive with does and/or what you feel good about. Its like anything else, many different opinions but find what works for you. Stay safe.

 

[PfcAJ]

There's an equipment solution ("failsafe") to a mental mistake problem that our team employs that serves two purposes. Having in-line shutdown valves on your deco/bailout second stages which are engaged on all but your bottom bailout means that a) if you grab the wrong gas at depth, you just won't get anything and b) you're unlikely to accidentally freeflow a bottle while scootering.

I like it as an insurance measure. YMMV

Or just turn them off?

 

[ajduplessis]

I'm not really a convert away from the idea that the main gas switching safety protocol is looking at and physically confirming the 2nd/hose/reg/tank before sticking it in your face.

Color schemes!! We agree as team on "color labeling systems". Everything is marked. Cylinders, cylinder valves, 1st stages, seconds and SPG's.

Back gas & bailout - White.
1st switch gas - Green (travel gas or 2nd switch gas - Green with White stipe)
Final deco gas - Red

Green and Red Examples