Survey question rebreathers

[Superlyte27]

I don't see any chest thumping. I see some people planning dives where in my opinion they're not taking enough gas. I see people planning dives where they are taking a bunch of gas. I see some agreement and disagreement, but no one has thumped any chests that I see. I was trained a certain way. I plan my dives the way I was trained. I agree with my training. And I've been doing this long enough that I've seen just about every perspective (and yes, that's some chest thumping).

I can't see the need to do a setup dive when I can take on a single dive ALL the gas to get out of the cave at the deepest point even if my CCR & scooter dive, and even if I lose my dive buddies. I don't think I could ask one of my students to plan more aggressively than that.

As far as "little prep" and "very little margin for error". What would a large margin of error be? I'm planning on 3 systems failing on a single dive. The system that is a rebreather. The system that is my transport, the scooter; and the buddy system. Aside from assuming half my OC bailout was going to fail, what other margin of error can I account for, lol.

For some of the guys on this page, diving to 10k is just another dive; because they're doing dives like this every week.

I'm also not sure what the cutting corners or dive time is referring to. Bailout is for the exit. And frankly, if you are on bailout you shouldn't be site seeing. You should be getting the hell out of the cave.

I guess it's just a matter of perspective. When you're doing 5 or 6 hours in a single dive, I'd really rather just take the bailout with me on that dive, rather than doing setup for two hours prior to it.

[Nitrogenius]

Team bailout, all good until one of the team is stuck in a restriction... but what are the odds? Nobody could see that coming..could they?

And of course if an OC Team of two was diving thirds and one diver had a catastrophic failure on of them getting stuck in a restriction would not pose an issue


I think it is important comapring apples and apples here..
Michael has illustrated the right comparisons..
Diving with the bare Minimum bailout = exact the amount of gas to get out from farthest Penetration equals diving thirds from an Equipment failure = loss of use angle..


Just his math is a little off.. Taking double Bailout = diving fiths neitehr fourths or sixths..


There is an angle though where all of the sudden double bailout is equaling thirds with a rebreather or not even making thirds..
It is the beast of CO2 !
Clearly the risk to get hypercapnia is much much higher on CC than on OC.. And then it really depends how you intend to plan for it.
I would still "just" plan to get out of the cave with my gas, but my "catastrphic" failure to plan for at max Penetration would be a Bail because of hypercapnia. Fortunately (?) I already had this experience in OW (I do not CC in Caves yet and might never do), so my OW deco planning foresees: 3 min @ max depth @ highly elevated SAC (70 lpm) and then the remainder at regular SAC x 1,5...
That would be my rule of thirds if I'd ever dove CC in a cave.. (OC I have no issues diving thirds in familiar cave with familiar Buddy)
And I'd still have an issue if I or my Buddy would then get stuck in a restriction

[floridabob]

No that's not what I said, I am just putting out what I would be comfortable with when a team of three divers plan a dive to 10k at 100'.
It seems as though everyone wants to cut gas to the absolute minimum. I am not comfortable with the minimum. Dives past 5 or 6k are not dives that I would try to cut to the bare minimum. If someone wants to treat a dive to 10k as if it was just another dive, then that's fine. I don't. AND if I am going to 10k I want to enjoy the dive and not have to cut corners or cut dive time in order to get the 10k glory marker, have at it but I think they are diving for the wrong reason. I realize that we would like to think of ourselves as explorers, but if it's got line already-you are just a tourist. To do one dive to setup and enjoy the cave and to carry one more bottle on the way out is not even an issue of inconvenience. It's more diving and more fun. This is not a debate as to who can do the dive with the least BO gas. If you want to be the one that will do it on an RB and a single 80-that's fine, but it is not what makes me feel warm and fuzzy.

Please tell me you are not attempting to call me out as gas cutting or chest thumping? Your proposal was less gas than mine, not more. 108x2 (plus overfill)=265 + 80 = 345 x 3 divers = 1035 total cf in cave for us. You, 730.

As for my comment about 24 80 cf tanks being needed....I'm not sure they would be needed in OC let alone CC. I just used your proposed exit amount and extrapolated for thirds in OC. It is exactly what you said in your post where you used SAC of .8 and exit at 50 FPM.

I am very comfortable with diving as I was taught: 2x estimated exit amount. Use more if you like. But that doesn't make the dive inherently safer nor me a chest thumper.

The amount of bailout has absolutely nothing to do with being able to sight see. The bailout amount is based on distance only in our examples, not any significant deco obligation. Therefore, the time you sight see in CC is irrelevant, only the linear distance from the exit.

I have stayed over an hour between 7500 and 8800 feet sight seeing and am constantly amazed at the thought that I ALWAYS have 2x the exit gas needed no matter how long I stay. Distance was the primary required BO exit variable necessary for that dive.

You do dive CC, H2OCaver, correct? Made me wonder when I read some of your thoughts.

Bob

[Superlyte27]

I agree with Bob with everything except one thing....

108/2640 * 3600 * 2

LP108's filled to 3600psi are 295cu' of gas + AL80 (77.4cu') = 372cu' of gas.

[rddvet]

You're all a bunch of strokes.

Put a spare air in your Drysuit pocket and man up.

[nakatomi]

You're all a bunch of strokes.

Put a spare air in your Drysuit pocket and man up.

Add a cave snorkel in the other pocket and you'll even be redundant.

[floridabob]

This just went sideways.

And with a mod's help, no less.

Meh...as expected. This was nearing intelligent discourse, can't have that.

Maybe this thread could be moved to Rebreather World?

Let's get back to recognizing birthdays in the main forum.

Bob

[floridabob]

I agree with Bob with everything except one thing....

108/2640 * 3600 * 2

LP108's filled to 3600psi are 295cu' of gas + AL80 (77.4cu') = 372cu' of gas.

I was rounding down out of respect to the "overfilling LP tanks" thread.

[nakatomi]

I'd have to go back through the entire thread, but if memory serves me right, I found a lot of very valuable information and can't detect any chest thumping either.
And Bob, when the heat is up, spare air may cheer up the crowd, even if it contains tire fills

[H2Ocaver]

I reread, no chest thumping, my mistake. OP just asked a question, I detailed what I would do. My assertions were based on unknown cave with my team and no need to rush. my gas calcs cover my minimummto feel comfortable.
Bob you have a solid plan, it's just different from what I would do.