Rebreather bailout

[MichaelAngelo]

Train wreck... start a new thread, has nothing to do with the OP post...

no need for new thread I was asked a question and tried to answer.

[RAL]

Rebreathers are not magic. By using one a diver is not somehow transformed into some uber diver able to McGiver himself out of the back of the cave with an old booty and a can on cool whip. SELF RESCUE should always be an option at LEAST when planning the dive. For the reasons listed already TEAM BAILOUT ain't the best idea, separation, increased gas use under stress.......... If everything goes perfect I guess a team of three or four might get out with one failure if they are not carrying 40s to swim back out from a million mile penetration. The thing is things rarely go perfect and once a cave demon is tugging on your fins things tend to go less perfect.
While expedient, yes you can cover more ground, common sense should come into play when considering team bail out. Let me ask this, if team bail out is such a good idea for rebreather diving why not use it for OC? Hey we are all able to decide on the degree of risk we are going to expose ourselves to but don't kid yourself about it. Be honest with yourself and your team mates. Bet those two or three 40s will start to look pretty damn small at 100' with a 2500' swim to you next gas supply.

RAL

[icestac]

With respect to team bailout, that's a no go for me. I mostly do solo CCR, so it has not been much of an issue. I have considered that if I were doing a big team dive, that we could stash more bottles along the way in -- perhaps 1 bottle every Xft instead of two bottles every Yft or something like that. I've not had to do that yet, but I've been thinking about the pros/cons of one vs the other -- gas is always within (X/2)ft of you BUT you'd be making more stops along the way so it could slow your exit.

With respect to the gas planning sub-conversation, my biggest fear with the rebreather is a CO2 hit. I'm not really worried about bailing out off a failing rig -- that is pretty easy to handle. But the body's response to uncontrolled breathing is the scary part. So my planning is less about needing 2x my normal OC gas to exit, but rather need AT LEAST as much gas to exit while sucking wind. So my simplified baseline for a non-working dive has been based on a square profile and elevated SAC rate (1.5). From there I can evaluate how much padding I want based on complexity of the site, team composition (all CC or mixed), contingencies for tank failure, etc.

So for instance in JB, I would plan on 99ft (4ATM) at 1.5 CFM = 6CFM required to exit on. If I know I will be within 35 minutes from the exit (35* 6 = 210cuft gas), then I know my SM LP85s would be JUST enough to get me back to my deco gas and I can add more gas onto that. I carry as much as possible on me and the remainder would be staged and dropped along the route.

This generally comes out to MORE exit gas than I would carry if I were OC, but I still have a better comfort level on CCR if any other non-CCR equipment failure situation were to occur as I would generally have more time to handle it.

Cheers,
Jeff

[Bobby]

Jeff,
We do the math a little different but arrive at the same reserves.

For staged cylinders I only use AL80's because they carry a good amount of gas, are easy to pick up, clip on, and can be dumped when used up. Dumping or exchanging my SM dil/BO cylinders would be time consuming and would change weighting.

Looks like there are more people carrying more BO than I thought before this thread was started. I know I see a good amount AL 40's on CCR cave divers and the majority on OW. Guessing that that side of the discussion is quietly sitting on the side lines.

Bobby

[MedCop]

My bailout changes depending on the dive, meaning OW or Cave. In an OW bailout situation my primary goal is to get as shallow as possible as fast as possible (The SW Predator with the GF99 is a very nice feature for this.) In OW a couple 40's really will get you out of just about any situation, yes, even a 200' dive with deco. One tank of bottom gas to get you to 70' and the other with 50%. You can do the math, but it does work. However, a couple AL72's in OW adds alot of padding to a bailout situation. BTW...I am not talking wreck penetration as that falls more into the cave bailout plan.

When in a cave I will take gas for me plus the reserve that I think is appropriate. Bailout is calculated on time to get out of cave or to get to a staged tank if the dive is going to be "way back" in the system. Generally, two AL72's or two 108's are my tanks of choice for cave bailout at a minimum. I will say, I never take less than two AL72's into a cave with me and will drop a 40 of 100% or a 40 of 50% depending on the cave. For instance when I dive Little River I drop a bottle of 50% further back in the cave as I can get onto this faster than waiting to get to a 100% bottle if I was in a deco situation.

[JoeyP]

Rebreathers are not magic. ....... Let me ask this, if team bail out is such a good idea for rebreather diving why not use it for OC?
RAL

Actually, the old OC rule of thirds is team bailout. A third in, a third out and a third for your buddy.

I believe it is important for divers to understand and know how to use team bailout even if they never intend to use it. Also, I am in no way promoting it in the article. I am simply saying that you should understand it because in the real world some of us will be in situations where the only option is to use team bailout or not dive. Some will opt to not dive but we all know that many will choose to do so. It is important that those who choose to dive fully understand the risks involved, how to minimize them and how to form and execute a viable plan. It is not something to learn on the fly.

Joe Citelli

[MichaelAngelo]

Actually, the old OC rule of thirds is team bailout. A third in, a third out and a third for your buddy.

Thats not totally true. A third in, a third out and a third for emergency not just for my buddy. At this level of diving self-rescue should be your first option. Your buddy is there to assit and give aid but self reliance is paramount. That third isn't exclusively for use by a buddy. We dive redundency for ourselves as well as our buddies. I will always be there for my team mate but if something goes wrong with my primary life support I am going to my backup before grabbing from my buddy.
One thing I learned in life from business and diving. There are Teammmates who are there everytime you need them and then there are people that are your buddy. Buddies can be like ex-wives - There always around when your giving them something, rarely there when you need them.

[JoeyP]

Agreed. That's why solo divers use a buddy bottle. 2 divers on doubles and one has a total gas failure at max penetration .... odds are he won't get out on his buddys third alone without a buddy bottle or some staged gas. My point is to understand what you are dealing with and make the proper adjustments.

Thats not totally true. A third in, a third out and a third for emergency not just for my buddy. At this level of diving self-rescue should be your first option. Your buddy is there to assit and give aid but self reliance is paramount. That third isn't exclusively for use by a buddy. We dive redundency for ourselves as well as our buddies. I will always be there for my team mate but if something goes wrong with my primary life support I am going to my backup before grabbing from my buddy.
One thing I learned in life from business and diving. There are Teammmates who are there everytime you need them and then there are people that are your buddy. Buddies can be like ex-wives - There always around when your giving them something, rarely there when you need them.

[bletso]

Self sufficiency... Each member of the team carries enough to get himself out. If it goes really bad, a team member can hand off a stage on the fly. We practice this regularly..

IMO, team bailout is marginal bail out planning and makes me uncomfortable.

Dale

[gsk3]

Actually, the old OC rule of thirds is team bailout. A third in, a third out and a third for your buddy.

Thats not totally true.

Thirded that this is nonsense. "Team bailout" in OC doubles would mean a quantity in, a quantity out, and half that quantity in reserve for emergencies. So the rule of 2/5ths. You would gain (40-33)=7% of your gas usable to increase penetration/bottom time, and you'd lose a huge margin of safety. Doesn't seem like a wise compromise to me.