Maybe eCCR's really aren't the wave of the future for recreational divers?

**Dave Sutton** · 10th June 2007, 01:26

Quote: (Originally Posted by abowie)

Nothing wrong with saying "I think there's something wrong here....".

Especially when it's pretty darned obvious that something is wrong.

It's either:

Equipment

or

Training

or

Technique

But it's "something".

I don't need to quantify that "something" before I take steps to avoid it. I'll take action first and study the "why" later.

Read my sigfile. That says it all.

Dave

**trob09** · 10th June 2007, 01:30

Quote: (Originally Posted by abowie)

True but in the same breath they'll also tell you that when no better data is available it's not unreasonable to make inferences based on what you do know.

Granted it doesn't mean that it's incontrovertibly right, but if it's the best data you have you'd be irrational to say that you didn't believe any of it because you didn't understand why it was happening. Nothing wrong with saying "I think there's something wrong here...."

This is the level of evidence that, for example, a large amount of medical therapeutics is based on. We tend to believe what we see and act on it until such times as better information becomes available.

In my opinion, it is irresponsible to make conclusions when we know that only the tip of the data ice-berg is being examined. Some who have looked at the available data on rebreather fatalities have assigned 'diver error' to a fair portion of those fatalities. Others have been attributed to pre-existing health conditions. Even though we know this data is grossly insufficient for identifying true causality, it is at least a start to examine a fuller range of factors that can contribute to dive accidents.

To wipe all of that off the table and say "Mccr's are proven to be safer than Eccr's" is, well, bullshit.

It is a fact that there are no recorded fatalities on Mccr's. (I'm not suggesting there is a "Mccr conspiracy here, the researcher in me is just acknowleging that there may be undoccumented ones - however unlikely that is. I don't believe there are, but the possibility exists.). To simply assign this record to the unit and not consider the other factors is short-sighted. For me, it opens the question "I wonder why that is..."

**trob09** · 10th June 2007, 01:32

Quote: (Originally Posted by Dave Sutton)

Not to make too much of a point to it, but there are a bunch of REAL idiots here diving Rebreather's. All of the idiots I have seen are diving eCCR's. I've never seen a mCCR diver that was not darned involved with his rig. That's just what I observe. I've seen some VERY squared away eCCR divers too.

It's just an observation. Don't receive an insult where none is intended.

Actual mileage may vary.

Dave

So, you see variations in the _diver_ and assign those variations to the unit. Interesting.

**trob09** · 10th June 2007, 01:37

Quote: (Originally Posted by Dave Sutton)

But it's "something".

I don't need to quantify that "something" before I take steps to avoid it. I'll take action first and study the "why" later.

Dave

Then how do you know you're avoiding the right thing? Equipment/training/technique - that's a pretty broad swath to cut. It's really easy to see what you want to see. Obviously, you're free to choose as you will. Me? I'll choose empirical data over anecdotal evidence any day.

**Gill Envy** · 10th June 2007, 01:39

Quote: (Originally Posted by silent running)

Sure Gill, but what's the Vision HUD for? Doesn't it work well enough to make checking the screen a once in a while activity? I would look at them, like I look at my analog 2dry, every few minutes...

Well, in the end it was her HUD that caught her attention, it did it's job allerting her with plenty of time to react, and she reacted accordingly, but the fact that one is more prone to stare at numbers for so long that eventually they stop thinking about them is still well illustrated in her experience, as she pointed out.

I personally see the HUD as a back up for those few minutes in between handset checks rather than a way to make those checks less frequent, but that's just the way I look at it. i just don't think the brain processes the info with the same resolution. the manufacturer did not intend it to be an primary, at least on the vision.

g

abowie · 10th June 2007, 01:47

The more I think about this thread the more convinced I am becoming that the central issue about safety here is about AWARENESS of what the unit is doing, and the nature of the machine itself is secondary.

If you train on an eCCR and trust it to do its job while paying only cursory attention to what's going on you'll get into trouble if it fails. Sure they start out by teaching you to fly manually, but why would you do that unless you were some sort of hyper vigilant safety freak like, oh I don't know, a test pilot or an anaesthetist? So if you let the machine do what you paid for it to do....

If you train on a mCCR you HAVE to watch what's going on because there's really no other way to dive the unit. So unless you get distracted or you can't monitor the displays you should be alright. There is no question in my mind that there will be situations with an mCCR where you die of hypoxia when an eCCR would have kept you alive. The gross available statistics we have to work with so far seem to suggest that this is a relatively unlikely event however.

Other cues apart from handsets, like an HUD, listening to the solenoid or in my case the KISS valve hissing are terribly important. In theatre I will notice if the patient's heart rate changes by more than a couple of beats per minute, no matter how otherwise distracted I am. Tens of thousands of hours of practise at monitoring get you used to the subtle cues.

So essentially I'm changing my mind mid thread and looking more at what you do rather than what you've got. Mind you, I'll still be getting another mCCR.

abowie · 10th June 2007, 01:51

Quote: (Originally Posted by trob09)

Me? I'll choose empirical data over anecdotal evidence any day.

So would anyone, but there isn't a lot of the former so the latter is all we have.

OK so practically, what do you suggest? Arguing semantics is all very entertaining but doesn't cut it in a practical sense.

**trob09** · 10th June 2007, 01:52

Quote: (Originally Posted by abowie)

The more I think about this thread the more convinced I am becoming that the central issue about safety here is about AWARENESS of what the unit is doing, and the nature of the machine itself is secondary.

If you train on an eCCR and trust it to do its job while paying only cursory attention to what's going on you'll get into trouble if it fails. Sure they start out by teaching you to fly manually, but why would you do that unless you were some sort of hyper vigilant safety freak like, oh I don't know, a test pilot or an anaesthetist? So if you let the machine do what you paid for it to do....

If you train on a mCCR you HAVE to watch what's going on because there's really no other way to dive the unit. So unless you get distracted or you can't monitor the displays you should be alright. There is no question in my mind that there will be situations with an mCCR where you die of hypoxia when an eCCR would have kept you alive. The gross available statistics we have to work with so far seem to suggest that this is a relatively unlikely event however.

Other cues apart from handsets, like an HUD, listening to the solenoid or in my case the KISS valve hissing are terribly important. In theatre I will notice if the patient's heart rate changes by more than a couple of beats per minute, no matter how otherwise distracted I am. Tens of thousands of hours of practise at monitoring get you used to the subtle cues.

So essentially I'm changing my mind mid thread and looking more at what you do rather than what you've got. Mind you, I'll still be getting another mCCR.

I agree 100%. While I also do not have data that proves causality, It is my belief that mindfulness and situational awareness are the key.

**trob09** · 10th June 2007, 01:54

Quote: (Originally Posted by abowie)

So would anyone, but there isn't a lot of the former so the latter is all we have.

OK so practically, what do you suggest? Arguing semantics is all very entertaining but doesn't cut it in a practical sense.

I think you've hit it. Pay attention - to the unit and to the dive. No matter what you dive.

Mike · 10th June 2007, 01:59

Quote: (Originally Posted by silent running)

But remember-and for anybody who doesn't know-the Prism HUD doesn't just tell you everything is OK. It tells you if any sensors have been voted out and if the battery is going, in addition to how high or low the PO2 is off SP. But if you've got the analoge PO2 gage, that info is available through it or not relevent.

It was this point that I was thinking about actually, and I'm not as convinced anymore.
Say I calibrated the Prism electronics in air rather than in 100%. (ie the calibrate button was accidentally pushed with the bucket off) The unit would try to hold .14 at the surface, and if the loop was at .14, the HUD would be indicating 'on setpoint' with no warnings active at all. So whilst the Prism HUD does give you PPO2 indication, it is giving you exactly the same information that it is running the solenoid off. So if there is a problem that means the electronics are acting on erroneous information that they think is correct, the HUD will not alert you to this.
(Example: a MK15.5 I saw recently had a fault where the electronics continually thought the unit was below setpoint. It would show the blue hypoxic light, and fire the solenoid, even though the PPO2 was 2+. The primary display was just displaying the same faulty information that was being used to drive the solenoid)

So I've decided that the 'primary' display used should be one that is completely independant of the electronics that are driving the solenoid. It's really the only way to verify that what the electronics think they are doing is what you actually want them to be doing.

Not sure there is a unit out there that has this though?

Units where both means of reading PPO2 is driven by one set of electronics don't give you a means for verification at all. I can now see why adding a 4th cell is so popular.

On the Prism, I had been running it off the HUD, and just checking the analog guage every now and then. Running with the electronics on and the HUD not working made me realise that hearing the solenoid fire at regular intervals was giving me exactly the same information as the HUD did - ie that the electronics throught that the loop was on setpoint. This made me think about how much I should be trusting the HUD rather than verifying with the analog guage.

(Note: the Prism HUD does give a bunch more info about any problems that occur, but during normal diving all it is displaying is a single green 'on setpoint' light. It's only this component of it's functionality that I'm considering)

So - anyone want to make a unit that has a digital readout of what the electronics think is going on as a secondary, plus a completely independant HUD that gives your PPO2 in analog form and can be used to fly the unit with the primary electronics turned off?

Mike
PS - Dave, I know we've beaten it to death and still disagree. Hope you don't mind that when I see you say that correct dil is essentual, if I counter with an alternate view that correct protocol can work for any dil. Let folks consider the alternatives, rather than accept one idea as gospel.
And if it means I'd not be welcome on your boat... oh well, I'm sure I can cope.
(FWIW, I think correct dil is a good idea, but I think that always using a protocol that will work for any dil is more important. And it saves having to dump dil)

10th June 2007, 01:26	#101 (permalink)
Dave Sutton Living on Animal Farm Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,626	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by abowie) Nothing wrong with saying "I think there's something wrong here....". Especially when it's pretty darned obvious that something is wrong. It's either: Equipment or Training or Technique But it's "something". I don't need to quantify that "something" before I take steps to avoid it. I'll take action first and study the "why" later. Read my sigfile. That says it all. Dave __________________ . "All animals are equal, but some animals are more equal than others" Professional Small Boy: Never Successfully Cubicled. Last edited by Dave Sutton : 10th June 2007 at 01:28.
(Offline)

10th June 2007, 01:30	#102 (permalink)
trob09 . Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Posts: 696	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by abowie) True but in the same breath they'll also tell you that when no better data is available it's not unreasonable to make inferences based on what you do know. Granted it doesn't mean that it's incontrovertibly right, but if it's the best data you have you'd be irrational to say that you didn't believe any of it because you didn't understand why it was happening. Nothing wrong with saying "I think there's something wrong here...." This is the level of evidence that, for example, a large amount of medical therapeutics is based on. We tend to believe what we see and act on it until such times as better information becomes available. In my opinion, it is irresponsible to make conclusions when we know that only the tip of the data ice-berg is being examined. Some who have looked at the available data on rebreather fatalities have assigned 'diver error' to a fair portion of those fatalities. Others have been attributed to pre-existing health conditions. Even though we know this data is grossly insufficient for identifying true causality, it is at least a start to examine a fuller range of factors that can contribute to dive accidents. To wipe all of that off the table and say "Mccr's are proven to be safer than Eccr's" is, well, bullshit. It is a fact that there are no recorded fatalities on Mccr's. (I'm not suggesting there is a "Mccr conspiracy here, the researcher in me is just acknowleging that there may be undoccumented ones - however unlikely that is. I don't believe there are, but the possibility exists.). To simply assign this record to the unit and not consider the other factors is short-sighted. For me, it opens the question "I wonder why that is..."
(Offline)

10th June 2007, 01:32	#103 (permalink)
trob09 . Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Posts: 696	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by Dave Sutton) Not to make too much of a point to it, but there are a bunch of REAL idiots here diving Rebreather's. All of the idiots I have seen are diving eCCR's. I've never seen a mCCR diver that was not darned involved with his rig. That's just what I observe. I've seen some VERY squared away eCCR divers too. It's just an observation. Don't receive an insult where none is intended. Actual mileage may vary. Dave So, you see variations in the _diver_ and assign those variations to the unit. Interesting.
(Offline)

10th June 2007, 01:37	#104 (permalink)
trob09 . Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Posts: 696	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by Dave Sutton) But it's "something". I don't need to quantify that "something" before I take steps to avoid it. I'll take action first and study the "why" later. Dave Then how do you know you're avoiding the right thing? Equipment/training/technique - that's a pretty broad swath to cut. It's really easy to see what you want to see. Obviously, you're free to choose as you will. Me? I'll choose empirical data over anecdotal evidence any day.
(Offline)

10th June 2007, 01:39	#105 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,302	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by silent running) Sure Gill, but what's the Vision HUD for? Doesn't it work well enough to make checking the screen a once in a while activity? I would look at them, like I look at my analog 2dry, every few minutes... Well, in the end it was her HUD that caught her attention, it did it's job allerting her with plenty of time to react, and she reacted accordingly, but the fact that one is more prone to stare at numbers for so long that eventually they stop thinking about them is still well illustrated in her experience, as she pointed out. I personally see the HUD as a back up for those few minutes in between handset checks rather than a way to make those checks less frequent, but that's just the way I look at it. i just don't think the brain processes the info with the same resolution. the manufacturer did not intend it to be an primary, at least on the vision. g __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
(Offline)

10th June 2007, 01:47	#106 (permalink)
abowie Fighting Girl Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: May 2005 Location: Land of Oz Posts: 573	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? The more I think about this thread the more convinced I am becoming that the central issue about safety here is about AWARENESS of what the unit is doing, and the nature of the machine itself is secondary. If you train on an eCCR and trust it to do its job while paying only cursory attention to what's going on you'll get into trouble if it fails. Sure they start out by teaching you to fly manually, but why would you do that unless you were some sort of hyper vigilant safety freak like, oh I don't know, a test pilot or an anaesthetist? So if you let the machine do what you paid for it to do.... If you train on a mCCR you HAVE to watch what's going on because there's really no other way to dive the unit. So unless you get distracted or you can't monitor the displays you should be alright. There is no question in my mind that there will be situations with an mCCR where you die of hypoxia when an eCCR would have kept you alive. The gross available statistics we have to work with so far seem to suggest that this is a relatively unlikely event however. Other cues apart from handsets, like an HUD, listening to the solenoid or in my case the KISS valve hissing are terribly important. In theatre I will notice if the patient's heart rate changes by more than a couple of beats per minute, no matter how otherwise distracted I am. Tens of thousands of hours of practise at monitoring get you used to the subtle cues. So essentially I'm changing my mind mid thread and looking more at what you do rather than what you've got. Mind you, I'll still be getting another mCCR. __________________ Andrew Bowie Rebreather-friendly Buddy
(Offline)

10th June 2007, 01:51	#107 (permalink)
abowie Fighting Girl Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: May 2005 Location: Land of Oz Posts: 573	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by trob09) Me? I'll choose empirical data over anecdotal evidence any day. So would anyone, but there isn't a lot of the former so the latter is all we have. OK so practically, what do you suggest? Arguing semantics is all very entertaining but doesn't cut it in a practical sense. __________________ Andrew Bowie Rebreather-friendly Buddy
(Offline)

10th June 2007, 01:52	#108 (permalink)
trob09 . Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Posts: 696	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by abowie) The more I think about this thread the more convinced I am becoming that the central issue about safety here is about AWARENESS of what the unit is doing, and the nature of the machine itself is secondary. If you train on an eCCR and trust it to do its job while paying only cursory attention to what's going on you'll get into trouble if it fails. Sure they start out by teaching you to fly manually, but why would you do that unless you were some sort of hyper vigilant safety freak like, oh I don't know, a test pilot or an anaesthetist? So if you let the machine do what you paid for it to do.... If you train on a mCCR you HAVE to watch what's going on because there's really no other way to dive the unit. So unless you get distracted or you can't monitor the displays you should be alright. There is no question in my mind that there will be situations with an mCCR where you die of hypoxia when an eCCR would have kept you alive. The gross available statistics we have to work with so far seem to suggest that this is a relatively unlikely event however. Other cues apart from handsets, like an HUD, listening to the solenoid or in my case the KISS valve hissing are terribly important. In theatre I will notice if the patient's heart rate changes by more than a couple of beats per minute, no matter how otherwise distracted I am. Tens of thousands of hours of practise at monitoring get you used to the subtle cues. So essentially I'm changing my mind mid thread and looking more at what you do rather than what you've got. Mind you, I'll still be getting another mCCR. I agree 100%. While I also do not have data that proves causality, It is my belief that mindfulness and situational awareness are the key.
(Offline)

10th June 2007, 01:54	#109 (permalink)
trob09 . Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Posts: 696	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by abowie) So would anyone, but there isn't a lot of the former so the latter is all we have. OK so practically, what do you suggest? Arguing semantics is all very entertaining but doesn't cut it in a practical sense. I think you've hit it. Pay attention - to the unit and to the dive. No matter what you dive.
(Offline)

10th June 2007, 01:59	#110 (permalink)
Mike Prism 'prentice Current Rebreather/s: Prism Topaz Other Rebreather/s: Inspiration Classic Evolution Join Date: Feb 2005 Location: Melbourne Posts: 325	Re: Maybe eCCR's really aren't the wave of the future for recreational divers? Quote: (Originally Posted by silent running) But remember-and for anybody who doesn't know-the Prism HUD doesn't just tell you everything is OK. It tells you if any sensors have been voted out and if the battery is going, in addition to how high or low the PO2 is off SP. But if you've got the analoge PO2 gage, that info is available through it or not relevent. It was this point that I was thinking about actually, and I'm not as convinced anymore. Say I calibrated the Prism electronics in air rather than in 100%. (ie the calibrate button was accidentally pushed with the bucket off) The unit would try to hold .14 at the surface, and if the loop was at .14, the HUD would be indicating 'on setpoint' with no warnings active at all. So whilst the Prism HUD does give you PPO2 indication, it is giving you exactly the same information that it is running the solenoid off. So if there is a problem that means the electronics are acting on erroneous information that they think is correct, the HUD will not alert you to this. (Example: a MK15.5 I saw recently had a fault where the electronics continually thought the unit was below setpoint. It would show the blue hypoxic light, and fire the solenoid, even though the PPO2 was 2+. The primary display was just displaying the same faulty information that was being used to drive the solenoid) So I've decided that the 'primary' display used should be one that is completely independant of the electronics that are driving the solenoid. It's really the only way to verify that what the electronics think they are doing is what you actually want them to be doing. Not sure there is a unit out there that has this though? Units where both means of reading PPO2 is driven by one set of electronics don't give you a means for verification at all. I can now see why adding a 4th cell is so popular. On the Prism, I had been running it off the HUD, and just checking the analog guage every now and then. Running with the electronics on and the HUD not working made me realise that hearing the solenoid fire at regular intervals was giving me exactly the same information as the HUD did - ie that the electronics throught that the loop was on setpoint. This made me think about how much I should be trusting the HUD rather than verifying with the analog guage. (Note: the Prism HUD does give a bunch more info about any problems that occur, but during normal diving all it is displaying is a single green 'on setpoint' light. It's only this component of it's functionality that I'm considering) So - anyone want to make a unit that has a digital readout of what the electronics think is going on as a secondary, plus a completely independant HUD that gives your PPO2 in analog form and can be used to fly the unit with the primary electronics turned off? Mike PS - Dave, I know we've beaten it to death and still disagree. Hope you don't mind that when I see you say that correct dil is essentual, if I counter with an alternate view that correct protocol can work for any dil. Let folks consider the alternatives, rather than accept one idea as gospel. And if it means I'd not be welcome on your boat... oh well, I'm sure I can cope. (FWIW, I think correct dil is a good idea, but I think that always using a protocol that will work for any dil is more important. And it saves having to dump dil) __________________ Open ....... Closed Mind ........ Loop
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode