Gas planning for diving in mixed company?

[stuartv]

I'm diving the Oriskany next week. I'll be diving OC. My buddy will be diving a CCR.

I'm only trained to carry 1 deco cylinder and plan to adhere to my training.

My training for planning is based on having a buddy that is also diving OC. Per that training, I would plan my deco gas cylinder so that my and my buddy's requirements are each less than half the size of the deco cylinder I'm carrying. So, if my buddy loses his deco gas, we can share mine and have enough for both of us. We would both be carrying twice as much as either of us would need.

Similarly, my rock bottom calculation is based on getting 2 divers from the furthest point in the dive to the first gas switch.

Since my buddy will actually be on a CCR and will be carrying BO cylinders of bottom gas and deco gas that will be sufficient to get him safely from the furthest point in the dive to the surface in the event he has a CCR failure, my thinking is that I do not need to reserve any of the gas I'm carrying for him. But, I can plan to use his, if needed.

So, my rock bottom planning would be for 1 diver, instead of the usual 2. And I can plan that if I have any lost gas, I can use one of his BO cylinders.

This thinking is all based on the usual approach of only planning for 1 failure. But, I don't know if that's valid when you're talking about a CCR diver. Is it? Is it acceptable to plan that if I lost my deco gas, I can just take the deco gas cylinder my CCR buddy is carrying? Is it acceptable to plan that if I somehow lose all my back gas, I can take the bottom gas BO cylinder my buddy is carrying?

Or does diving with a CCR have elevated risk such that a CCR diver would/should never dive with a plan that includes him having to donate one of his BO cylinders to someone else?

I will discuss all this with my buddy, of course. But, I want other opinions just to reassure me that if he says this is an acceptable plan, there is no part of his acceptance that is based on a feeling of pressure from me or a willingness to compromise on safety to get decent bottom time when he's handicapped by diving with an OC diver. I don't believe he would do any of that. I'm just paranoid and like to get other perspectives on the relative safety of what I'm proposing.

 

[Doby45]

With your bud being on CCR, I would plan the dive as solo. Plan for YOUR gas as the CCR diver should be doing the same from his CCR training. There comes a point in time when you can over complicate something to the point of it not even being worth doing. Have you also checked with the diver charter to see if they offer O2 at 20ft? I mean it is a tech charter I would assume and that could be part of your lost gas plan. I also have not done AN/DP yet so this could be all total rubbish.

 

[Lorenzoid]

With CCR so common these days, it's interesting that they don't teach you in AN/DP how to dive in mixed teams.

 

[stuartv]

With your bud being on CCR, I would plan the dive as solo.

I have considered that approach. The result is MUCH less bottom time.

The boat is not a tech charter. We'll probably be the only 2 tech divers there.

On the one hand, I can plan it as a solo dive. On the other hand, I can plan it the normal way, where I'm planning that if I lose either of my gases, I will share what my buddy is carrying. The latter seems reasonable. And gets a LOT longer bottom time - especially since my rock bottom doesn't have to allow for gas for him. But, as I am not a CCR diver, I don't feel qualified to say that it's okay to plan to take any of the gas he's carrying.

 

[stuartv]

With CCR so common these days, it's interesting that they don't teach you in AN/DP how to dive in mixed teams.

My instructor doesn't have any CCR experience. 1 demo dive, I think. And his circle of buddies all also dive OC, I think.

I guess it's just not that common (yet, anyway) for buddies to be diving in a mixed group like we will be. Last year, when I dived with this buddy for 2 weeks, we had a 3rd member of our team that was also on OC, so I didn't have this problem. The CCR guy was diving solo, for practical purposes.

 

[packrat12]

Your CCR buddy may not have much gas to spare if on BO. I plan all of my dives solo and expect the OCs to do the same. If someone needs my gas, there is very very little to spare and definitely not enough to have my CCR fail at the worst point and then the OC to do the same. I have donated my BO's before to an OC with OOG. It is not a good feeling and you are really hoping the CCR works normally through the deco. Truly there is no excuse for a technical diver to run out of gas!

 

[Got2Go]

Discuss this with your CCR buddy.
You BOTH need to be ok with the plan.

Otherwise, you are not really diving together, so plan solo.

 

[Nasser]

My instructor/buddy dives CCR so I plan gas for myself.

 

[stuartv]

Your CCR buddy may not have much gas to spare if on BO. I plan all of my dives solo and expect the OCs to do the same. If someone needs my gas, there is very very little to spare and definitely not enough to have my CCR fail at the worst point and then the OC to do the same. I have donated my BO's before to an OC with OOG. It is not a good feeling and you are really hoping the CCR works normally through the deco. Truly there is no excuse for a technical diver to run out of gas!

Right. The plan would be based on the assumption that we would not both have a failure. And that is really the root of what I'm asking. As a CCR diver, is it considered acceptable to plan that you and your buddy will not both have a failure, so it's okay to plan for the CCR diver to donate his BO, if his buddy has a failure?

From an OC perspective, the CCR diver's BO is all "redundant". And from an OC perspective, I wouldn't plan for both divers to need redundant gas. But, I could see where CCR is not as reliable as OC, so CCR BO may not be considered "donatable". I think I've seen some threads about CCR diving and "team bailout" with different opinions on that. I guess, in a sense, the plan I'm describing would be somewhat akin to team bailout, in that he would be carrying gas that he knows he might have to donate.

Maybe the appropriate plan would be that he plans to carry enough gas to cover us both. I.e. he could bail and I could lose my deco gas, and he would be carrying enough deco gas for us both?

My original thought was that he would only be carrying enough BO gas for one of us - on the basis that we only plan for 1 failure - either him OR me, but not both. But, if we planned it so he was carrying enough for both of us, then that would solve part of the problem. It wouldn't solve the part where we would have to buddy breathe to share... Or that we might need more gas than an AL80 holds...

Depending on what he says, maybe I'll just hang a cylinder of deco gas on the anchor line. Hmmm....

 

[stuartv]

Discuss this with your CCR buddy.

I will discuss all this with my buddy, of course. But, I want other opinions just to reassure me

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