Diver missing - Pelham, Alabama

[Dr. Lecter]

Well that changes things a little. If it was a RMS enabled system, then the odds a bypass/burn-through are really low if he was on his first dive of the day (assuming he didn't drive for hours with it prepacked). Perhaps someone should ask the authorities to contact paul, im sure he would be more then willing to help (especially if it is a unit failure).

Daru

Paul's posted a bit about it on RBW, I assume he'll be in touch with them.

And I see giana still can't tell the difference between the odds changing and there being any odds at all. Oh well.

 

[gianaameri]

Well that changes things a little. If it was a RMS enabled system, then the odds a bypass/burn-through are really low if he was on his first dive of the day (assuming he didn't drive for hours with it prepacked). Perhaps someone should ask the authorities to contact paul, im sure he would be more then willing to help (especially if it is a unit failure).

Paul's posted a bit about it on RBW, I assume he'll be in touch with them.

And I see giana still can't tell the difference between the odds changing and there being any odds at all. Oh well.

A properly working CO2 Sensor might change the odds (direct measurement of CO2), not a RMS on a rEVO (an indirectly derived estimate of scrubber duration).

The rEVO does not have a CO2 Sensor, hence I do not think one was fitted to the unit used for this fatal dive.

Even then, if in reliance of a CO2 Sensor, or any other device (i.e. RMS, Temp-stick...), the diver exceeds the tested limit of its scrubber, then risk increases, rather than decrease.

Risk would decrease only if you fit a CO2 Sensor AND remain within the tested scrubber limit.

What else exactly am I missing that I don't understand from a risk perspective?

 

[Dr. Lecter]

A properly working CO2 Sensor might change the odds (direct measurement of CO2), not a RMS on a rEVO (an indirectly derived estimate of scrubber duration).

The rEVO does not have a CO2 Sensor, hence I do not think one was fitted to the unit used for this fatal dive.

Even then, if in reliance of a CO2 Sensor, or any other device (i.e. RMS, Temp-stick...), the diver exceeds the tested limit of its scrubber, then risk increases, rather than decrease.

Risk would decrease only if you fit a CO2 Sensor AND remain within the tested scrubber limit.

What else exactly am I missing that I don't understand from a risk perspective?

You're forgetting that to exceed the tested limits of the scrubber, one would have to actually reproduce the test conditions. Similar to NDLs and multilevel profiles, nobody generates that much CO2 which is why the RMS is so useful. Running 4 hours on a scrubber meant to be swapped after 2 hours under very different conditions is not "exceeding the tested limits" of said scrubber: it's measuring the reaction front your personal CO2 production and the temps of the dive are creating and working from there. Whether you think that's sufficiently conservative or not is your own business, but to claim the RMS is used to exceed a limit is pants on head _________.

More broadly, what you're missing from a risk perspective is that the odds with modern CCR technology are much better now than even just several years ago. They're still not as good as OC, but the odds on OC are much worse than snorkeling. Strangely enough, you're not advocating snorkling.

Anyway, past experience with you in the Carlos thread suggests that your combination of language barriers and other issues will prevent any productive discussion, so I'll leave you to your rantings.

 

[gianaameri]

You're forgetting that to exceed the tested limits of the scrubber, one would have to actually reproduce the test conditions. Similar to NDLs and multilevel profiles, nobody generates that much CO2 which is why the RMS is so useful. Running 4 hours on a scrubber meant to be swapped after 2 hours under very different conditions is not "exceeding the tested limits" of said scrubber: it's measuring the reaction front your personal CO2 production and the temps of the dive are creating and working from there. Whether you think that's sufficiently conservative or not is your own business, but to claim the RMS is used to exceed a limit is pants on head _________.

More broadly, what you're missing from a risk perspective is that the odds with modern CCR technology are much better now than even just several years ago. They're still not as good as OC, but the odds on OC are much worse than snorkeling. Strangely enough, you're not advocating snorkling.

Anyway, past experience with you in the Carlos thread suggests that your combination of language barriers and other issues will prevent any productive discussion, so I'll leave you to your rantings.

The RMS is an attempt to predict scrubber duration taking into account a number of parameters, none of which actually measure CO2.

Far safer to stay within the tested limits of the scrubber, rather than to exceed them.

If the RMS causes the diver, all other things being equal, to exceed the tested limit of the scrubber, the consequence is that the diver will be exposed to greater risk.

If on this fatal dive the diver relied upon the RMS (if fitted) to exceed the tested duration of the scrubber, the diver took more risk, than it would have otherwise - without an actual direct measurement of CO2 (the rEVO has no CO2 Sensor, as much we know) to confirm that the predictive value of the RMS was actually correct.

More broadly, a number of known faults have been fixed over time in rebreathers, hence these are less risky than they were before. Sadly, we still have to contend with a number of unexplained fatalities in well trained and experienced divers - which is less than reassuring.

The Carlos thread is a separate topic.

 

[uwxplorer]

gianaameri has a point. If you dive a rebreather and you pass away, you'll die alone.

Let's expand:
- death by hypoxia: you will not feel it coming, and by the time your buddy will see you pass away, it will be too late.
- death by hyperoxia: if you don't have a gag strap, you'll spit out your mouthpiece and will drown. Chances of resuscitation if brought back to the surface by a buddy are close to nil. If you do not drown, only another qualified reberather diver can potentially help you remedy the problem (flush the loop with diluent, bail you out or bring you shallower).
- death by hyperoxia: whether or not you have a BOV, if you are unable to bailout to OC, it is unlikely that a buddy can do much to help you out.
- if you have a medical emergency, a buddy might be able to bring you to the surface, but there is no guarantee that it will save your life (this is true for OC diving too).
In other words, rebreather diving comes with a lot more risks than OC diving, and not many can be alleviated by the presence of a buddy. At least not that I have been told during training. We are trained to be de facto solo divers, and the only time where a technical diver will plan to rely on his budd(ies) is when he is forced to use team bailout planning. As a rebreather diver, you need to keep practicing to stay on top of your game and your unit. By doing so, you also add wear and tear on your unit, and run into the danger of creeping complacency. And therefore you need to further train to avoid that. I would argue that having a buddy to keep track of (especially in murky conditions like seem to be the norm in this quarry), is more of a distraction to this overall goal than an advantage. Although that could be the goal of the dive: let's make it more challenging by diving with a buddy...
OC diving to be safer does nothing to help with the above.

Getting back on track: the only thing that matters for this A&I is the circumstances and root cause of the painful loss of a fellow diver. So far, this thread has not provided any information that could help elucidate it.

 

[gianaameri]

http://www.al.com/news/birmingham/i...n_yet_for_what_ca.html#incart_related_stories

 

[HIGHwing]

I really hope that if I ever die on one of my rebreathers in a quarry or somewhere it isn't absolutely logistically necessary one of my dive buddies will write on this board what dive I was training, practicing, or preparing for next.

All this chatter about a CCR not being perfectly appropriate or not necessary for this specific dive is all nonsense when you consider that the deceased might have been prudently practicing in the OW for a much more complex technical deep, or cave, or perhaps even a deep cave dive.

Had this same gentleman not practiced in the OW for a big deep cave penetration these same voices would be saying, "The deceased got in trouble because he didn't know his rig; he should have been more prudent and prepared under more controlled, open water, no overhead type conditions." These conditions are present for the most part in a quarry. Eagles Nest is no place to test your bailout rigging to see if you can reach it all in your brand new dry suit.

It is not for you to decide what dive I may attempt next, or what equipment I might use to complete it. I use rebreathers for cave and deep stuff, and you can believe that I make "equipment unnecessary" rebreather dives to prepare. This includes testing rigging, practicing skills, and making sure weighting and balance work with various bottle and exposure suit configurations.

If you are advocating that CCR should only and ever be used when they supply a specific logistical advantage then you are advocating for a less experienced, less current, and a less safe CCR community and I see no cause or justification for this shaming or your overall position.

 

[gianaameri]

If you are advocating that CCR should only and ever be used when they supply a specific logistical advantage then you are advocating for a less experienced, less current, and a less safe CCR community and I see no cause or justification for this shaming or your overall position.

Was the deceased "practicing in the OW for a much more complex technical deep, or cave, or perhaps even a deep cave dive" or was he just using his rebreather simply because he wanted to dive it for the fun of it?

 

[nimoh]

Was the deceased "practicing in the OW for a much more complex technical deep, or cave, or perhaps even a deep cave dive" or was he just using his rebreather simply because he wanted to dive it for the fun of it?

does it matter?

why don't we assume the diver was not doing anything unsafe until it is proven that he was instead of the other way around?

 

[PfcAJ]

does it matter?

why don't we assume the diver was not doing anything unsafe until it is proven that he was instead of the other way around?

You want 'proof' of something related to a dive accident? You must be new here