How great is the risk (in your perception)?

[Wookie]

Not sure you mean me. If you do:
Just trying to wrap my head around things. Not meaning any harm or headaches to anyone in the process. Not sure I would think I am asking for great thoughts... just trying to learn from what others already learned... and also trying to work through or better around a minefield of sales oriented dumbed down info...
Either way, we are all divers on one level or another, maybe deep thoughts will do?
But that might then really be opening a can of worms...

The OP has 2 excellent threads going, not the typical SB fare, but real questions that require real thought, the answers of which could change the industry if enough people saw them. It wasn't about you, except that you are thinking and participating too.

 

[Schwob]

The OP has 2 excellent threads going, not the typical SB fare, but real questions that require real thought, the answers of which could change the industry if enough people saw them. It wasn't about you, except that you are thinking and participating too.

Agree. Excellent threads, both of them.

 

[wedivebc]

The only 2 fatalities on the Poseidon that I know of were both in shallow water on very simple dives. The only issue was both of them were not trained on the units and just jumped in. One had a low battery, ignored all the warnings and did 2 dives with the unit. He died from hypoxia after the unit shut down everything but the solenoid, eventually there was no power for that either.

The other guy jumped in with the O2 tank off, the unit fired up and tried to keep him alive. He descended so the loop PPO2 stayed breathable until he got to depth, by the time he paid attention to all the alarms and flashing lights, he reverted to his OC background and swam straight up. He died when the PPO2 dropped on the ascent. If he had turned the BOV he would have survived.

These accidents are part of that “recreational dive CCR fatality” statistic.

This is an example of the rebreather being unforgiving of human nature rather than a failure of the rebreather. Even though rebreathers like any other machine can fail, a properly trained diver, following proper procedures can mitigate and failure the rebreather might experience. That is the point of training. Those that take shortcuts, ignore alarms, or dive beyond their limits are the ones who end up making the rebreather look like the villain. We have lost many experienced and well respected RB divers in the past but if you look at what actually happened you will always see an element of human failure.

 

[wedivebc]

I am a CCR diver. A few of my thoughts.

I disagree with the statement "most of the incidents are user error". It is not fair or correct to blame user error when the user has not been taught properly. O2 cell linear deviation and cell limiting are, IMHO, the most important topics a CCR diver needs to understand completely. 99% of the classes barely give the subject lip service much less teach it to a level of understanding. There are instructors and IT's that will tell students that linear deviation and limiting are hog wash, which only makes things worse. I have heard such nonsense as "don't do an O2 flush at 20', you will bombard your cells with O2". I've also heard that "no cell will actually be linear".

I'm not sure where you are getting this statistic from. Can you quote a source or are you referring to just the instructors you know? I can say categorically that every CCR instructor I know, and every one I have trained put great emphasis on cell limitation and deviation. So I guess myself and all my associates are the 1%.

Upon closer examination of your post I find I disagree with most of what you contend is being taught by the majority of rebreather instructors. These might be popular myths on online forums but no one I know of supports any of these statements you claim are commonplace.
Can you please direct me to these blogs and papers you have written?

 

[Bobby]

Dave,
I know I put a percentage however I didn't mean it as a statistic, I should have said "most". I know this from listening to and talking to CCR IT's, instructors, and many many students. Instructors will say that they teach and students say they understand linear drift and limiting, however dig just a bit into the subject and it becomes obvious that most don't. I have personally spent hours with many CCR divers as well as instructors explaining it.

I've spoken with so many CCR divers and have heard all and many other things stated so many times there is no way that all of the people came away from their classes with the same so called "internet myths". I don't recall anyone telling me that an instructor explained to them in class why they don't need to calibrate, if it is not needed. Much less why it wouldn't be needed or how calibration is one of the easiest ways to make a mistake when setting up their CCR. Most of the people that I speak with don't know what they need to watch for when flushing O2 or why they need to watch the mv instead of PO2 readout. Far too many believe that calibrating their unit is ensuring that their cells are linear and a few even believe that by calibrating the controller is making their cells linear.

If you are covering all of these things and get your students to understand the "why", great and good on you (I mean that seriously). There are far too many that are not and that is from direct conversations with a lot of people with many questions from me. I've also spoken with agencies and manufacturers regarding linear deviation and limiting. I've heard answers across the board on why it is not being covered in depth.

I've touched on this subject on this and other boards many times over the years. I've also sent write ups to agencies and manufacturers. Here is one recent one that I have not yet finished, however have shared with a few agencies and manufacturers. Another by Paul Raymaekers, which is more in depth however may be confusing as a first step into understanding linear drift and limiting. I mean not disrespect to Paul in any way, I'm simply saying that it gets technical.

 

[wedivebc]

Dave,
I know I put a percentage however I didn't mean it as a statistic, I should have said "most". I know this from listening to and talking to CCR IT's, instructors, and many many students. Instructors will say that they teach and students say they understand linear drift and limiting, however dig just a bit into the subject and it becomes obvious that most don't. I have personally spent hours with many CCR divers as well as instructors explaining it.

I've spoken with so many CCR divers and have heard all and many other things stated so many times there is no way that all of the people came away from their classes with the same so called "internet myths". I don't recall anyone telling me that an instructor explained to them in class why they don't need to calibrate, if it is not needed. Much less why it wouldn't be needed or how calibration is one of the easiest ways to make a mistake when setting up their CCR. Most of the people that I speak with don't know what they need to watch for when flushing O2 or why they need to watch the mv instead of PO2 readout. Far too many believe that calibrating their unit is ensuring that their cells are linear and a few even believe that by calibrating the controller is making their cells linear.

If you are covering all of these things and get your students to understand the "why", great and good on you (I mean that seriously). There are far too many that are not and that is from direct conversations with a lot of people with many questions from me. I've also spoken with agencies and manufacturers regarding linear deviation and limiting. I've heard answers across the board on why it is not being covered in depth.

I've touched on this subject on this and other boards many times over the years. I've also sent write ups to agencies and manufacturers. Here is one recent one that I have not yet finished, however have shared with a few agencies and manufacturers. Another by Paul Raymaekers, which is more in depth however may be confusing as a first step into understanding linear drift and limiting. I mean not disrespect to Paul in any way, I'm simply saying that it gets technical.

Thank you for your clarification. If this has been your experience speaking with rebreather instructors and ITs that is rather troubling.
I'm happy to say this hasn't been my experience but that does not negate yours.

 

[Capt Jim Wyatt]

If this has been your experience speaking with rebreather instructors and ITs that is rather troubling.

I'm happy to say this hasn't been my experience....

Same here, very happy.

 

[ofg-1]

The biggest risk to me personally would be my wife finding out that I laid out $7500 plus for a rebreather and training. She's a mean little woman with a large pair of pinking shears that could de-ball me in one midnight snip. At my age, they are mainly for decorative purposes, however, I am somewhat used to having them.

 

[DepthCharge]

Commenting on the posts about instructor not teaching certain things about rebreathers. (I'm not an instructor). In a week course one couldn't possibly teach everything you need to know about RB(s). Also some students would grasp a certain concept quickly, but other concepts more slowly. They're kind of dependent on each other. I've had some very good instructors, but to be honest, I learned more after the courses. No reflection on the instructors, but both did tell me I would learn more after.
Just my 02c.
John

 

[Capt Jim Wyatt]

@Bobby

I read your blog comments that you attached to your previous post. I consider this basic cell knowledge that all CCR divers MUST understand.

It is actually pretty simple stuff. I have never had a CCR diver pass a CCR class that I taught that did not understand this stuff.

I cannot imagine an Instructor or IT that doesn’t fully understand this.