Eagles Nest Cave Diver Death

[ianr33]

How do they do that, Dave? Is it based on time? I mean, I can imagine with a CCR that you have to use some other kind of metric than gas consumption to set a turn parameter for the dive

Not a rebreather diver so take this for whats it is worth:

Basically comes down to penetration distance,depth and SAC rate. I normally figure I swim at around 50 feet/minute in a large cave with no flow. If you know depth profile and SAC rate it would be pretty easy to calculate the necessary bailout.

 

[Cave Diver]

My understanding is they only had one bailout each. If that's the case, they didn't have enough bailout for the dive. Had they taken a CCR cave course they would have known this...

How do you know this?
What was the BO gas?
What was the dive plan? Team BO or individual?
What was the size of the BO tank, start pressure?
Where there any other tanks staged? Top of mound? Log at 20ft?
If staged tanks what were the sizes, psi and gas?
What is the diver SAC/RMV?

These are the questions that would occur immediately to me if someone told me that they only had one BO tank and before I would make the judgement.

Also, they should have learned how to calculate gas requirements much earlier than on a Cave CCR course.

If they truly had only two OC tanks available as a team then I am lost for words. I cannot imagine a scenerio in which they could have gotten out running out of gas or missing deco with planning a total CCR failure at maximum penetration.

John

To have planned this, they would have had to have been CCR caved trained . . . which, as the answer is 'not', is the unfortunate answer to all your questions above.

Has a formal 'initial report' been given on the incident?

I don't think this is true. All cave divers are trained to calculate needed gas for exit -- and technical divers are trained to calculate needed gas for gas loss or deco gas loss. One of the most defining things about technical or overhead diving is that you have to solve such problems where you are. If they were not carrying enough bailout (and I don't know this and haven't seen any informed report anywhere) then either they just didn't think about it, or they made some very questionable decisions about how much was enough.

However, nothing I have read says that anyone ran out of gas here, so whether the bailout was adequate or not does not appear to have had a chance to play a role, unless it was simply by increasing the victim's anxiety.

There are many unanswered questions in this accident, but the big one is why he had already bailed out, and why he went back on the loop. We may be lucky enough, as we were with Richard Mork's death, to get a report on the condition of the equipment, but more likely, we won't, and we will never know.

Rebreathers continue to scare me.

The BIG difference is OC divers use the gas consumed on entry to gauge the gas required to exit (1/3rds) CCR divers have to rely on whatever OC experience they have to gauge predicted gas requirements and I suspect many fall short of their estimation of gas consumption.

How do they do that, Dave? Is it based on time? I mean, I can imagine with a CCR that you have to use some other kind of metric than gas consumption to set a turn parameter for the dive -- whether that's just penetration time, or how much deco you want to rack up, or whatever. And if you set that parameter, and you know what depth you're doing, it shouldn't be too hard to calculate OC gas consumption. At least, I had to do those calculations in my Cave 1 class.

No, really, some have argued for having a hot dil so that in a dil flush you'd get a ppO2 of 1.8 or something like that. I think the argument flared up after there was an accident or two which was possibly attributed to hypoxia due to doing a dil flush near the surface with something like 10/70.

To have correctly planned and executed the dive at hand in this case, one needed to be Cave, CCR and Trimix trained. Lacking any one of these would raise the risks exponentially, especially diving a CCR and the depth.

I have dived EN on both OC and CCR. Each time I did, it was planned in advance, with the correct gases and volumes, RT plans and contingencies. Always a fresh scrubber in the breather and cells that tracked correctly.

I am not saying these two divers did not plan it correctly, all I am pointing out is that this is not a dive you 'just go do'. By not crossing all T's and dotting all i's, having even the slightest issue will put you over the line of no return.

Not a rebreather diver so take this for whats it is worth:

Basically comes down to penetration distance,depth and SAC rate. I normally figure I swim at around 50 feet/minute in a large cave with no flow. If you know depth profile and SAC rate it would be pretty easy to calculate the necessary bailout.

I'm not splitting this discussion as it's relevant to the accident, but I'm going to start a separate thread so that some of the questions regarding CCR can be explored without sidetracking the accident discussion. Here is the link: http://www.scubaboard.com/forums/rebreather-diving/311125-ccr-truths-misconceptions.html

 

[jkaterenchuk]

No, really, some have argued for having a hot dil so that in a dil flush you'd get a ppO2 of 1.8 or something like that. I think the argument flared up after there was an accident or two which was possibly attributed to hypoxia due to doing a dil flush near the surface with something like 10/70.

Well I guess I have missed that thread on RBW. I thought I had read all of them. I am certainly aware of the discussion on using a hypoxic mix when not required for the dive. As well I am aware of the discussion on using a DIL with oxygen greater than 21%. But I have never read anything as the way your explaining it. Maybe you could point me to the exact post on RBW?

John

 

[jkaterenchuk]

How do they do that, Dave? Is it based on time? I mean, I can imagine with a CCR that you have to use some other kind of metric than gas consumption to set a turn parameter for the dive -- whether that's just penetration time, or how much deco you want to rack up, or whatever. And if you set that parameter, and you know what depth you're doing, it shouldn't be too hard to calculate OC gas consumption. At least, I had to do those calculations in my Cave 1 class.

Thats the basic concept I was taught on my CCR cave course.

John

 

[Dive-aholic]

How do you know this?
What was the BO gas?
What was the dive plan? Team BO or individual?
What was the size of the BO tank, start pressure?
Where there any other tanks staged? Top of mound? Log at 20ft?
If staged tanks what were the sizes, psi and gas?
What is the diver SAC/RMV?

These are the questions that would occur immediately to me if someone told me that they only had one BO tank and before I would make the judgement.

Also, they should have learned how to calculate gas requirements much earlier than on a Cave CCR course.

If they truly had only two OC tanks available as a team then I am lost for words. I cannot imagine a scenerio in which they could have gotten out running out of gas or missing deco with planning a total CCR failure at maximum penetration.

John

Go back and read the initial reports. The survivor apparently offered his bailout to the dead diver three times and was refused all three times. There was 1000psi left in the dead diver's BO bottle (no s at the end of that statement). The BO was reported as being 18/30, same as dil. I don't know the plan, or even if there was one. I believe the BO bottle was an 80, but I can't remember if that was stated for sure or not. I haven't seen any mention of staged tanks. But if they really only had one 80 BO bottle each and were on the egress at 270' depth, 500' penetration, even with a RMV or .4 (which is doubtful), they would blow through more than a third of the BO gas at that depth in 10 minutes. The dead diver blew through 2/3s of it before going unconscious. Maybe I'm over conservative, but I'd want at least one bailout per diver plus at least one other bottle in the system other than deco bottles, depending on the plan.


Lynne, as for calculating how much bailout is needed, it's based on RMV, depth, and penetration. I have actually put to test how much it takes me to get out of Jackson Blue from 2500'. I can swim out on an AL80 with plenty of gas left. Two AL80s will get me out of there from the EOL with plenty left. Based on this, I know 2 BO bottles would be enough for me no matter where in the mapped sections of JB I am. And this is with the flow down. It's all about planning.

 

[jkaterenchuk]

Go back and read the initial reports. The survivor apparently offered his bailout to the dead diver three times and was refused all three times. There was 1000psi left in the dead diver's BO bottle (no s at the end of that statement). The BO was reported as being 18/30, same as dil. I don't know the plan, or even if there was one. I believe the BO bottle was an 80, but I can't remember if that was stated for sure or not. I haven't seen any mention of staged tanks. But if they really only had one 80 BO bottle each and were on the egress at 270' depth, 500' penetration, even with a RMV or .4 (which is doubtful), they would blow through more than a third of the BO gas at that depth in 10 minutes. The dead diver blew through 2/3s of it before going unconscious. Maybe I'm over conservative, but I'd want at least one bailout per diver plus at least one other bottle in the system other than deco bottles, depending on the plan.

I have read all the reports on 4 different boards. So no need to question my ability to read. Often the tank which the CCR diver carries that he would plan to use if he needed to come off the CCR loop is called the BO Tank and the other tanks are called deco tanks. None of the other reports mention if any staged deco tanks were used in the dive. Your earlier posting made it sound like you had been given some kind of special information not yet posted in any of the other boards that the team had only two tanks between them and nothing else to facilitate OC deco if needed.

My response was simply to question what other information you might have to allow us to put more of the gas planning into perspective. It seems clear now that you really know nothing more that what was already posted.

Additionally, you state that the diver blew thru 2/3rds of gas from the BO tank. You have no idea if that was the case since you do not know what psi the tank started with for this dive. In fact your 2/3 assumption woulld indicate they started with 3000psi which is a little on the low side for a tank fill in Cave country as I am sure you know.

John

 

[wedivebc]

No, really, some have argued for having a hot dil so that in a dil flush you'd get a ppO2 of 1.8 or something like that. I think the argument flared up after there was an accident or two which was possibly attributed to hypoxia due to doing a dil flush near the surface with something like 10/70.

I find that very hard to believe. Can you provide a link?

 

[Dive-aholic]

I have read all the reports on 4 different boards. So no need to question my ability to read.

Dude, relax a bit! I don't think "Go back and read the initial reports." qualifies as questioning your ability to read.

Often the tank which the CCR diver carries that he would plan to use if he needed to come off the CCR loop is called the BO Tank and the other tanks are called deco tanks. None of the other reports mention if any staged deco tanks were used in the dive. Your earlier posting made it sound like you had been given some kind of special information not yet posted in any of the other boards that the team had only two tanks between them and nothing else to facilitate OC deco if needed.

How does this statement:

My understanding is they only had one bailout each. If that's the case, they didn't have enough bailout for the dive. Had they taken a CCR cave course they would have known this...

make it sound like I have been given some kind of special information?!?!?

BO bottles and deco bottles are very different. It doesn't matter what type of diving someone is doing. Deco bottles typically carry gas mixtures with higher percentage O2 for decompression. BO bottles should carry bottles with a mix that can be breathed where they are intended to be used. There has only been mention of one BO bottle for each diver.

My response was simply to question what other information you might have to allow us to put more of the gas planning into perspective. It seems clear now that you really know nothing more that what was already posted.

Additionally, you state that the diver blew thru 2/3rds of gas from the BO tank. You have no idea if that was the case since you do not know what psi the tank started with for this dive. In fact your 2/3 assumption woulld indicate they started with 3000psi which is a little on the low side for a tank fill in Cave country as I am sure you know.

John

If he had less than 3000psi then it was definitely not enough to be used as a BO bottle. If he was topped off with a cave fill then he breathed through a lot more than what I posted. In either case, the point I was trying to make is proven. My guess is that most everyone else who read my post probably got that. Apparently, you didn't.

I'm not here to argue with you. This is a discussion thread about a fatality. People are speculating and discussing various possibilities. I'm not sure why you've chosen to single me out, but you seem to be taking my statements personally, as well as certain things about this incident.

 

[jkaterenchuk]

Dude, relax a bit! I don't think "Go back and read the initial reports." qualifies as questioning your ability to read.



How does this statement:



make it sound like I have been given some kind of special information?!?!?

BO bottles and deco bottles are very different. It doesn't matter what type of diving someone is doing. Deco bottles typically carry gas mixtures with higher percentage O2 for decompression. BO bottles should carry bottles with a mix that can be breathed where they are intended to be used. There has only been mention of one BO bottle for each diver.



If he had less than 3000psi then it was definitely not enough to be used as a BO bottle. If he was topped off with a cave fill then he breathed through a lot more than what I posted. In either case, the point I was trying to make is proven. My guess is that most everyone else who read my post probably got that. Apparently, you didn't.

I'm not here to argue with you. This is a discussion thread about a fatality. People are speculating and discussing various possibilities. I'm not sure why you've chosen to single me out, but you seem to be taking my statements personally, as well as certain things about this incident.

I questioned you because you seem to have injected information which was new at the time. Specifically,

"My understanding is that they only had one bailout each"

I did not read this on any of the other four boards before you posted it here.

I have no personal tie to any of the people in this incident my only goal was to get you to clarify the source and accuracy of the statement you initially made in your post so that I can draw my own conclussion. Simple enough.

John

 

[rigdiver]

No, really, some have argued for having a hot dil so that in a dil flush you'd get a ppO2 of 1.8 or something like that. I think the argument flared up after there was an accident or two which was possibly attributed to hypoxia due to doing a dil flush near the surface with something like 10/70.

Per IANTD standards the Dil should not exceed a ppO2 of 1.0 at depth(from memory and practice.) This is so you could drive the ppO2 down if needed. Like a faulty solenoid injecting O2.
In Richard's case his Dil was topped of with EAN32 before his dive. NEDU analyzed 26% Oxygen. So at 90ffw he could not drive the ppO2 down fast enough IF he knew he was O2 toxing. His buddy Dan did see bubbles which MAY have been a dil flush.
And, yea 10/70 close to the surface is nothing to play with.
Take the classes if you want to play in these specialized environments.
Bill