Survey question rebreathers

[floridabob]

Looking at reserves and bailout from the point of view of x times what I need to get out is simply wrong. It should be taught to plan to survive catastrophic failures.

I must be missing this. Whats more catastrophic than having to bail out? Having to bail out and lights out?

Clarify for me, if you dont mind, Jason. Curious of your direction on this thought...

[CCRMichael]

totally true this why I love teaching for TDI or IANTD because they don't say there is only one way to do it. Being flexible is one of the most important things to learn. Even if you don't plan to do tank swapping I am glad you learned it. I think it is funny how many people who sidemount say they would just hand off a tank to their buddy if needed but I would be a certain amount of these people have never even tried it. It is not rocket science but the first time you do it should not be in an emergency in a cave.

I preach a lot about team principles but I also enjoy the solo CCR cave dive every now and again

Michael--I didnt think you were preaching Team Bailout. And I understand and respect the principles you are offering.

For me personally, I am anti-tank swapping. Not saying it wasnt taught and cant be done. Just that I wont use it as my go-to plan. I am not conducting high level exploration dives by any standard but hope to...and the plan for the group is generally different than what it sounds like you guys use.

Too much bailout can be complex, cumbersome and even counter-productive. I agree on that. There is a tipping point, as always.

And acting like a team is defined by the team. For instance: on one dive it was decided that, in the team of three all CC, if one has an issue he would peel off and the other two would continue. Gotta have my own gas in that scenario. I respect others would not want that plan and would go a different route. That was our advance decision and we were prepared accordingly.

I enjoy the interplay of ideas and different processes. One is not necessarily more right or better than the other. Usually, anyway.

Bob

[SlowDiver]

Michael I agree with you about passing the tank. By swapping tanks there are some advantages. If your buddy is on CCR and has to bail by breathing a aluminum down a third at lease it doesn't become too much of a floater. When diving with a OC diver by handing off a bottle you are not tethered to each other so you are able to exit quicker.
Now for us solo divers plan on using more gas than normal when emergency happens.


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[Bobby]

To answer the OP, for me I won't go in the water without two BO cylinders on a 40 foot reef dive much less a cave dive. I learned through experience that having two sources of BO is important on every dive because there are others in the water and when they need gas it is good to have another source of BO for myself. I also use 1.0 for the working part of the dive. If I am just doing one dive that day and diving in a mixed team I will sometimes kick it up to 1.2 to have my deco schedule the same as the OC diver.

Diving 1/3's on OC is a bare minimum and I can't remember the last time I have pushed to 1/3's on OC, it has been many years. CCR BO has nothing to do with OC diving. The failure possibilities are vastly different and the gas requirements to recover from possible failures on CCR are completely different from OC. Diving CCR in its self raises a persons RMV on OC much less having a CO2 hit will send RMV off the charts. Planning CCR BO based on OC RMV is planning for failure IMO. Having 2X the gas to exit with a normal RMV is most likely not going to be enough gas when a real BO situation has occurred. Knowing how much gas someone else in a team will need in a true SHTF situation is even more of a crap shoot. The very lat thing I want to do in a stressed situation is have to hand off a cylinder to give someone gas. I have a 7' hose for donation and a necklaced short hose for me. Each cylinder will have enough gas to get me out with a highly elevated RMV. If the dive requires more gas then I add stages that have a 5' hose. If the dive is long enough to require too many stages to carry at one time then set up dives are in order.

If others want to plan using team BO that is their option. It is my option to not dive with them. When diving in a team I carry more gas not less. I know how I have reacted when things go bad and rely on that experience to plan my dives when diving solo. I have also seen others react poorly when it goes bad and I want to have enough gas to handle the situation so we both get out.

Bottom line is that this is for fun. Even when doing exploration it is recreational. The caves are not going anywhere and taking the time to carry enough gas for bad situations is just the start. When I used to climb I never had a desire to do so without a rope and when I dive I have no desire to carry the minimum gas.

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[Greenwood_60]

Looking at reserves and bailout ONLY from the point of view of x times what I need to get out is simply wrong. It should be taught to plan to survive catastrophic failures.

I must be missing this. What's more catastrophic than having to bail out? Having to bail out and lights out?

Clarify for me, if you don't mind, Jason. Curious of your direction on this thought...

I've added a "ONLY" (in bold) to my above quote, which is more along the lines of my intended statement.

I'm saying thirds has little to do with being 2x the amount of gas you need to get out, and everything to do with surviving (only) a single catastrophic failure.

A catastrophic failure of a discrete system. Not specifically OC or CC. You rebreather is one discrete system, and an independent cylinder is another. A pair of doubles is one discrete system. Catastrophic failures are worst case, and are what must be planned for. A catastrophic failure leaves any of those systems unusable. You can't plan based on partially functional systems. Solo in doubles without a buddy bottle is stupid by any sane account.

Survival planning should be planned based on surviving a reasonable number of failures. How likely is a failure requiring bailout? How likely are you to lose your back gas? Or a single cylinder? Or lose a stage? Lose deco gas, bottle stolen? How many failures can you survive, and what are the odds of those failures. We all carry at least 3 light. Why? Because at one time they were very prone to failure. How many of our dives would we survive 2 major breathing system failures?

The problem I see with team bailout is not the quantity of gas, it's the reliability of buddies. You are taking a very reliable OC system, and putting it on a diver of unknown reliability. Can you survive a flooded loop and problems getting gas from a buddy? Lost buddy, trouble passing tanks, panicked buddy, silt out, another flooded loop, missing deco cylinders, etc.. Too many added points of failure, and increased odds of failure.

We should be identifying points of failure, assessing the probability of failure, and adding redundancy where the odds get too thin for our own preference.

[jj1987]

At 100ft depth, you could easily go through 4-5 AL6's in under 10 minutes, so you'd need at least 5-10 of them.

Hopefully this helps.

[Greenwood_60]

Yes, strawman, it helps.

[floridabob]

I was looking for an example of how you (Jason) would plan for a failure: gas, time, etc. I get all the potential problems. I'm curious of a specific scenario and your gas/exit plan. I don't think 2x BO encompasses only one failure. And planning a double OC BO failure in addition to a CC failure means just stay home...you wouldn't dive SM or BM let alone CC. Certainly CC has more potential failures but adding OC as BO doesn't multiply the issues exponentially to me. You?

The principle of when in doubt, bail out is very straight forward. You also can run open loop, SCR, or other. Lots of gas available on you in CC...not less than OC, MORE! Assuming my 2x bailout.

I have everything an OC diver has PLUS.

James...AL 6? You mean 6 cf tank? Or liter? I miss the point here, maybe?

Good discussion and I appreciate the input.

Bob

[cerich]

Team bailout, the perfect strategy when one emergency is not enough of a test of your skills, and the skills of the recovery divers.

[Superlyte27]

I chuckled a little when I found out what Odin's real name is.

So, last week I planned a scooter dive to the far end of a cave. The goal was 10k' I plan my bailout pretty much the same all the time. How long will it take me to swim out? I'm assuming my CCR is going to die, my scooter crapped out, and my buddy didn't notice and kept on scootering, leaving me alone in a cave. I was teased a bit for this approach when we started planning our dive.

So, how much gas would you bring to a cave dive with an average depth around 100' back 10,000'. It was three divers, all CCR. 4 Scooter. My dive buddies wanted to bring 2 AL80's each. Sure, if we all brought AL80's that would be 464.6cu' split between 3 people. But what if I lost my buddies, will 155cu' get me out of a dive 10k back? Sure, maybe, if I had perfect breathing, no anxiety, and nothing else went wrong.

Imagine, swimming 10k'. What pace can you keep up? 80fpm? That's 125 minutes. What's your gas consumption going to be? You're all alone in a dark cave, your scooter and rebreather have just taken a crap. Can you maintain a .5sac? I don't think so, but who knows. Let's assume a .6 sac. So lets figure .6 x 3.73ata x 125 minutes = 280cu'. And frankly, I don't believe you can maintain both 80' per minute because of the winding/up & down nature of the cave and a .6sac rate. So for me, I think it's more realistic to calculate 75pfm and a .75 sac rate. Remember, who knows how bad things got when scooter and rebreather got screwed up, how long is it going to take you to gain composure? So, now we're at .75 x 3.73 x 133 = 372cu' of gas.

Sure, this is assuming several things went wrong. And I agree, 99 out of 100 times, you're not going to have both things die and you lose your buddy. But what happens that 1 out of 100 times? I don't ever want to count on my buddy to survive. I also don't ever want to count on my one scooter to survive. I'm just not that trusting. And the peice of mind that comes with enough gas to swim out makes for stress free diving.

That's my perspective anyway.