Doing Tech+Cave on a RB?

[limeyx]

It's an interesting proposal eh? A Cis, or Meg in their hands would be quite interesting? Not that they would given the DIR philosophy. Just an "if" scenario.

Given the vast offerings of CCR's out there now, + varied protocols there is bound to be gaps somewhere. With GUE that variability is greatly reduced. There's a huge degree of "built-in" safety right there. On another note, I could have trained on the RB, or PVR years ago but having seen the fridge in action I thought...stay with the doubles and eventually moved to the CCR. My lower back and abdomen thanks me.

I wouldn't say that SCR's are necessarily safer. I do remember some issues with proper care, wrong mixes which may contributed to some SCR death on an either a RB clone, or PVR unit in Africa. Again, it's been a while.

If anything, the point I am trying to make is that attitude is the primary determinant in using these things, or expedition class diving. Attitude meaning: physical conditioning, desire to be a lifelong learner, never taking the cheap route, built-in degree of paranoia/global awareness and humility etc.

Sure, attitude is undoubtedly a huge part of it, BUT I think with a CCR, even with the right "attitude" some of the failures are just not detectable (how do you handle the mix going hypoxic when you have already passed out?). Maybe there are some things attitude cannot fix.

I have actually wondered for a while if diving a rebreather gives one an attitude of invincibility, or if they just attract a higher percentage of people that already have that attitude. I would like to hope it's the latter.

I honestly dont know how or if a CCR would help on dives like the WKPP are doing. The WKPP guys (and GUE too) like a relatively low PPO2 on the bottom so that you can (in theory) get a better benefit by spiking it up more on deco.

I also dont know if the caves they dive vary in depth significantly. If they did then maybe the CCR keeping the PPO2 constant would be a benefit.

I know the EKPP dive exactly this situation on RB80 (cave goes from 100M to 30 to 120 all over the place etc.) and that is solved to an extent by taking more than one drive bottle (a very crude way to change the PPO2

I think the WKPP would probably still plan for OC bailout, so I don't see that area changing much.

What benefits specifically are you thinking would be achieved ?

 

[limeyx]

That's the first concern I have with the OP's desire to skip OC training and go straight to the RB. Its not the concept of doing so, its that one of the drivers is to save money.

Don't ever try to save money doing this stuff. 1) its futile and 2) its a dangerous attitude to have.

You mean I can't just buy one wing and have it work for doubles and singles? Darn, I thought I could save a couple of hundred

 

[rjack321]

You mean I can't just buy one wing and have it work for doubles and singles? Darn, I thought I could save a couple of hundred

Just slap a bungie on it

 

[JeffG]

Just slap a bungie on it

and break apart your double 72's and use them for deco bottles.

 

[Mr.X]

Sure, attitude is undoubtedly a huge part of it, BUT I think with a CCR, even with the right "attitude" some of the failures are just not detectable (how do you handle the mix going hypoxic when you have already passed out?). Maybe there are some things attitude cannot fix.

I have actually wondered for a while if diving a rebreather gives one an attitude of invincibility, or if they just attract a higher percentage of people that already have that attitude. I would like to hope it's the latter.

I honestly dont know how or if a CCR would help on dives like the WKPP are doing. The WKPP guys (and GUE too) like a relatively low PPO2 on the bottom so that you can (in theory) get a better benefit by spiking it up more on deco.

I also dont know if the caves they dive vary in depth significantly. If they did then maybe the CCR keeping the PPO2 constant would be a benefit.

I know the EKPP dive exactly this situation on RB80 (cave goes from 100M to 30 to 120 all over the place etc.) and that is solved to an extent by taking more than one drive bottle (a very crude way to change the PPO2

I think the WKPP would probably still plan for OC bailout, so I don't see that area changing much.

What benefits specifically are you thinking would be achieved ?

I can only speak for my set of experiences and those of my teammates on ECCR/MCCR. They happen to be typically meticulous in their approach and execution. Without doubt, bad stuff can happen and sometimes it does. Luckily, not to me, or anyone in my circle. Is there a correlation, perhaps? Also, I have had bad days on certain units. I longer use the Insp.

As per safety, The HUD (which the Cis had early on) is a great tool which almost every rebreather diver wants to have - should have. That helps. Audible alarms less so. Interestingly enough, the KISS makes me paranoid enough that I monitor the heck out of the unit. To date, no fatalities. Says something about constant monitoring...related to training protocol or attitude. As you infer, I don't trust these things either. I also don't trust my OC kit.

In the end, I am less about endorsing one over another as long as the job gets done. That's why I don't voceriferously defend these things. No need to develop the afore mentioned "invincible" attitude. These days I could easily skip the CCR and go back to OC (unless it's Jeff's 130's - ouch!) just because it's easier and bypasses all those possible areas of failure and damn RB maintenance.

X

 

[lamont]

GUE has their way of doing things, and its not a bad way (if you discount the attitude that some member wear around like a hairy shirt), but they do not embrace the CCR pathway to anything. SCR's as a class of rebreather SUCK. This is not picking on the RB80 at all, its probably the best of the breed. However, for any kind of deco diving, all SCR's are no better than a long lasting cylinder of nitrox, they do not give the "best mix" except at one depth of the dive, CCR's give 'best mix" for the entire length of the dive and ALL depths, automatically, thereby providing the absolute fastest deco and least on gassing of any diving style.

There are several RBW members who are running their CCRs at much lower setpoints to back off on the oxtox risk a lot. There's also been discussion of how to get eCCRs to do backgas breaks, and there's been speculation on RBW that the low incidence of KISS fatalities to date may be partially due to the mCCR operation allowing ppO2s to drop more than an eCCR unit would typically allow. The "best mix/shortest deco" route does not seem to be universally viewed as being the best actual way to dive without any downside to it...

( And this is without bringing up what DIR/GUE think of constant setpoint diving -- these are your own buddies over on RBW... )

 

[limeyx]

As per safety, The HUD (which the Cis had early on) is a great tool which almost every rebreather diver wants to have - should have. That helps. Audible alarms less so. Interestingly enough, the KISS makes me paranoid enough that I monitor the heck out of the unit. To date, no fatalities. Says something about constant monitoring...related to training protocol or attitude. As you infer, I don't trust these things either. I also don't trust my OC kit.

....
X

My point is -- what if the HUD gives you bad info? The O2 sensor goes? With a CCR you are essentially reliant on a computer that can fail.

With OC, generally when something goes wrong you get a cloud of bubbles or no gas delivered -- very easy to tell. From my (very limited) understanding of the RB80 I think you get a similar thing (no pure O2 injected, fails to deliver gas if PPo2 too low?) The main failure mode that's hard to detect on the RB80 seems to be scrubber issue.

it seems to me that the CCR is inherently less safe than the other two methods (given current technology anyway), and no kind of "attitude" can really fix that.

 

[rjack321]

My point is -- what if the HUD gives you bad info? The O2 sensor goes? With a CCR you are essentially reliant on a computer that can fail.

With OC, generally when something goes wrong you get a cloud of bubbles or no gas delivered -- very easy to tell. From my (very limited) understanding of the RB80 I think you get a similar thing (no pure O2 injected, fails to deliver gas if PPo2 too low?) The main failure mode that's hard to detect on the RB80 seems to be scrubber issue.

it seems to me that the CCR is inherently less safe than the other two methods (given current technology anyway), and no kind of "attitude" can really fix that.

There's no pure O2 injection with the RB80. And you can hear the injector fire. The "manual" method of changing setpoints by plugging in different gases seems like alot of switching to me.

Regarding scrubber life and/or failure that seems unavoidable. Although the Cis membranes can at least tolerate being wet (right?) without making a toxic cocktail.

 

[limeyx]

There's no pure O2 injection with the RB80. And you can hear the injector fire. The "manual" method of changing setpoints by plugging in different gases seems like alot of switching to me.

Regarding scrubber life and/or failure that seems unavoidable. Although the Cis membranes can at least tolerate being wet (right?) without making a toxic cocktail.

I didnt mean to say the RB80 has O2 injection -- maybe my post was just worded poorly.

 

[rjack321]

I didnt mean to say the RB80 has O2 injection -- maybe my post was just worded poorly.

Yeah I figured that. The lack of pure o2 being both a benefits and a liability depending on who you ask!