Differences between eCCR’s and mCCR’s design that may effect mortality rates

**Dave Sutton** · 4th February 2007, 01:23

Quote: (Originally Posted by UWSojourner)

This reminds me of the "doctor killer" airplane. Forget the type of plane it was. But doctors were being killed in them because they could afford the high performance plane. Their new plane was capable of getting them into situations they weren't capable of handling. Maybe the eCCR is doing the same.

The original was "The V-Tailed Doctor Killer" which was the V-35 Bonanza (Beech). Now it's a generic term for a high performnce single engine airplane.

The "MCCR = 0 and ECCR = Lots" does *just about* say it all.....

Dave

***ScubaDadMiami*** · 4th February 2007, 04:37

Okay, let's break it down a little more (though I doubt there will be meaningful data to do it): How many eCCR deaths occured where the diver was flying manually above a lower set point?

**Gill Envy** · 4th February 2007, 04:40

Quote: (Originally Posted by silentscuba)

Gill- No matter what you do with a pure MCCR you will only be adding more failure points if you try to blend an ECCR and a MCCR.

Since it seems that some ECCR divers want the unit to be able to take care of them if they have a problem, the best idea that has come out that could be added to a MCCR is the "PARACHUTE SYSTEM".

That idea came about to address safety of a diver having a problem and not being able to manage a minimum PO2. The "PARACHUTE SYSTEM" is set up to add O2 if the PO2 drops down to a certain setpoint, say .4. But, now you have added new electonics, fittings, batteries, solenoid etc.

I feel that the "PARACHUTE SYSTEM" on a Constant Flow MCCR would be the closest to a blending of both types of rebreathers.

As far as the depth ratings, most units can be upgraded to be able to handle most any depth that you want.

Just my thoughts.

Curt that is certainly an understandable perspective overall. I'm inclined to agree that a "parachute o2 injection system" would add more failure points in the most critical system, and perhaps even more importantly not engage the diver as thoroughly in the PO2 monitoring process since he/she would now feel confident that their screw up would not result in death.

Correct me if I’m wrong, mCCR divers are relying on more and more electronics either by virtue of design or "add on's" as it is. The Copis for instance relies on electronics for PO2 monitoring and incorporates a HUD. So far it seems that a constant po2 computer or even two are a common addition to the mCCR mix. Complexity seems to be carefully embraced more and more in all areas except the life critical area o2 injection and po2 monitoring. That is why I’m questioning if the added complexity of all other components of an eCCR except the solenoid auto 02 injection system are really the issue. they may very well all be useful tools since they aren't related to po2 balance. In other words, they provide more benfits than risks. Auto injection of o2 seems to be the one major area that likely provides more risks than benefits under current design and or style of use(a change in style of use or design may change this down the road, but for now seems to be the likelyhood).

I guess my point is that it may not be the Simple, in the "Keep it Simple Stupid" philosophy but the “Manual" o2 injection in mCCR that is the key. The added failure points may not turn out to be the determining factor, or the reliance on electronics per se but very specifically the reliance on electronics to balance the po2 and that may even come down to the way such a design allows a diver to become un-engaged in the process more than risk of malfunction.

While it's true that mCCR's are simpler, it also seems true to me that they are only truly manual at the point that oxygen is needed to be added by the diver periodically, particularly on ascent. An mCCR with two constant po2 computers is complex (3 displays to monitor... and pricey), but remains simple in the way that seems to count the most. It's unintuitive that the added task loading of monitoring three screens and manual injection is outweighed by the apparent benefits of the constant flow orifice and "topping off" required by the diver. That is, IMHO, why so many folks making the switch from OC go directly to eCCR, because they feel that it's safer due to less task loading...that would be my wife and I.

It seems that as time goes, more electronics are added on to mCCR's by manufacturers and that does not seem to be effecting mortality rate, at least not yet. In fact the addition of an electronic po2 monitor early on likely drastically reduced the fatality rates of early mCCR's. And now the Copis in particular has a HUD, this could be seen as added complexity as well.

Where this leads me is: if the downsides of a constant/manually adjusted o2 flow system can be overcome by in design advancements, it seems compelling that leaving this one function out of an eCCR and in the hands AND brain of the diver may turn out to have a dramatic impact on fatality rates either by virtue of encouraging "safer" habits or by virtue of it being in some other way more reliable.

Even if you loaded up the system with an Auto On switch, temp stick, co2 monitor, built in deco computer combined with the po2 monitor viewed by a primary and perhaps a secondary display, maybe even a totally independent constant po2 computer like a VR3 and an HUD...but incorporated a truly manual o2 injection system, i'm guessing the fatality rates of this style m/eCCR hybrid would match that of the mCCR (although i'm sure eventurally someone is going to die on an mCCR or this style hybrid eCCR just by virtue of odds).

It seems to me that the trend is slowly happening, what you call it is immaterial; an electronic mCCR or a manual injection eCCR.

It looks an awful lot like it's either actually "safer" or it instills "safer" habits to have manual o2 control regardless of what other components are electronic. Why the fatality rates are lower is debatable in the end, but the fact remains, and it's one of the few solid facts we have, fatality rates on mCCR's are much lower than eCCR's and I think it's worth trying to identify how eCCR's could be improved with this knowledge.

anyone's thoughts are welcome.

decoweenie · 4th February 2007, 05:34

Quote: (Originally Posted by ScubaDadMiami)

Okay, let's break it down a little more (though I doubt there will be meaningful data to do it): How many eCCR deaths occured where the diver was flying manually above a lower set point?

All of them, unless you could prove otherwise.

We are missing a lot of the general data from the incident, and you are looking for the needle...

DonalWalsh · 4th February 2007, 06:25

Quote: (Originally Posted by Mark Chase)

KISS type MCCR deaths......None

ECCR various units deaths.. Loads

That about sums it up really.

However i once told a friend and DIR diver that once DIR became mainstream dick heads would start diving DIR not because they really believed it but because they thought it was cool.

Then the system will break down.

Rightly or wrongly I believe a lot of divers moved to the Meg because the Inspo was seen as dangerous and the Megs image was one of superior design in every way.

That didn't work

I fear that divers will choose MCCR not because they 100% believe in the concept of being part of the unit but because of its safety record. Then Darwin will kick in and we will have a spat of MCCR deaths.

On the other hand its 11.40pm and I am a bit cheesed off so maybe i am being negative about the whole thing

ATB

Mark Chase

Nope- you're not. You hit about three nails on the head there.

bletso · 4th February 2007, 14:26

I think you all are missing the boat! Once you add a "parachute system" to an MCCR, it is no longer a true manual system. It is a very simple ECCR. It will make or at least attemp to keep you alive.

In a true MCCR, the only thing that keeps you alive is Dave Sutton's "Thumb/brain connection" (TBC). Use any type computer or monitoring system for PO2, deco, CO2 you want, but the plain SIMPLE fact is YOU keep YOU alive via the TBC.

I choose not to use a HUD because I use two primary displays. If I mounted them where I could see them all the time, they would become distracting, perhaps to the point of not seeing them. (It's a basic human reaction. Familiarity breeds contemp.) A HUD is normally a secondary display. I don't use them!!!!! (Secondary displays)

Keeping all that in mind, would I be able to do a 100MSW dive? Yes, because I use a high IP and a small orifice. But 100 MSW is my design's limit. It actually is about the limit for pressure of the orifice placed by the manufacturer.

If I wanted to go deeper, then I would have to go to an ECCR system. But how many of us dive deeper? I do not. Most of my venues are less than 70 MSW and the vast majority are 50 MSW or less.

FYI, I do a lot of shallower dives on my MCCR. I don't add O2 on ascent because I don't have to. I have maintained a proper PO2 during the dive. I do a diluent flush before ascent. (habit) If its a deco dive, and many are I do my off board gas switches at the appropriate depths,do the purges and voila, it works.

Dale

**Gill Envy** · 4th February 2007, 17:07

Quote: (Originally Posted by bletso)

I think you all are missing the boat! Once you add a "parachute system" to an MCCR, it is no longer a true manual system. It is a very simple ECCR....
Dale

Dale, I think your perspective is certainly understandable and it may turn out to be the most accurate. However, the thing that perplexes me is that "parachutes" are already being added on a regular basis to mCCR's with no change in mortality rates... po2 monitor, HUD, Multiple deco computers with the specific exception of an automatic o2 injection system. It's very tempting to me to therefore conclude that is is not overall complexity that is the deciding factor but the manual addition of o2 and monitoring of po2 by the diver.

It may also be that the parachutes that are being added are mostly independent of one another. If composed of totally independent systems, it would seem that a manual injection eCCR would likely prove just as safe as modern day mCCR's...that is until the risks of auto injection systems, either due to style of use or failure points are overcome by advancements.

Dutchy · 4th February 2007, 17:13

Being on top of your condition is what keeps you alive I think. Adding a single HUD is about the dumbest design decission possible. Do you really add three cells and separate displays only to forget all about them because you start relying on a single hud?
HUD = Electronics. I hate electronics especially every component that apears to be electronincs but is in reality embedded software. And we all know software is less tangiable than mechanics so failures aren't as easily spotted.
But I have a watchdog. Yeah right. Does your watchdog do something when your AD converter failed? I don't think so and on top watchdogs are programmed as well.
I've seen failures in other life sustaining equipment. Luckily that was medical equipment scrutenized in a factory acceptance test after thousands of hours of testing in a far more rigid regime.
The botom line. If you want to use a HUD you should be able to REALLY rely on them, making them primaries. In fact that means you need to have two. My advice would be to use two from different vendors so as to rule out identical errors in them. If I'm right and failing equipment IS a factor then the the majority of future mccr fatalities will be amongst HUD users rather than mere display users. Without saying it goes that three displays on a single piece of electronics gives one the same potential problems. I love well designed equipment. Safety is not only in the number of cells but also in what you do with that info.

silentscuba · 4th February 2007, 19:20

Quote: (Originally Posted by Dutchy)

Being on top of your condition is what keeps you alive I think. Adding a single HUD is about the dumbest design decission possible. Do you really add three cells and separate displays only to forget all about them because you start relying on a single hud?
HUD = Electronics. I hate electronics especially every component that apears to be electronincs but is in reality embedded software. And we all know software is less tangiable than mechanics so failures aren't as easily spotted.
But I have a watchdog. Yeah right. Does your watchdog do something when your AD converter failed? I don't think so and on top watchdogs are programmed as well.
I've seen failures in other life sustaining equipment. Luckily that was medical equipment scrutenized in a factory acceptance test after thousands of hours of testing in a far more rigid regime.
The botom line. If you want to use a HUD you should be able to REALLY rely on them, making them primaries. In fact that means you need to have two. My advice would be to use two from different vendors so as to rule out identical errors in them. If I'm right and failing equipment IS a factor then the the majority of future mccr fatalities will be amongst HUD users rather than mere display users. Without saying it goes that three displays on a single piece of electronics gives one the same potential problems. I love well designed equipment. Safety is not only in the number of cells but also in what you do with that info.

I dive a KISS Classic. I have an integrated Shearwater and a HUD from a different manufacturer. They are both independent from each other except for the 3 O2 cells.

I use my HUD as a tool to keep my O2 swing to a minimum and to give me a quicker indication of a problem.

I do not use it as my primary O2 indicator. I feel that it does increase my safety and helps me keep a more constant PO2. If my primary does fail, the HUD gives me a reliable backup to help get me back out of the water.

I love my HUD and my Shearwater

Dutchy · 4th February 2007, 20:16

Quote: (Originally Posted by silentscuba)

I dive a KISS Classic. I have an integrated Shearwater and a HUD from a different manufacturer. They are both independent from each other except for the 3 O2 cells.

I use my HUD as a tool to keep my O2 swing to a minimum and to give me a quicker indication of a problem.

I do not use it as my primary O2 indicator. I feel that it does increase my safety and helps me keep a more constant PO2. If my primary does fail, the HUD gives me a reliable backup to help get me back out of the water.

I love my HUD and my Shearwater

You got the idea. Imho one of theproblems is that many don't know the design of their unit and consequently they don't know whether they are putting their eggs in the same basket or not. Some stuff in the market looks redundant but isn't. The way you did it makes sense with your attitude. I myself would - over time - be tempted to trust the HUD and forget about the primary...

4th February 2007, 01:23	#21 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Quote: (Originally Posted by UWSojourner) This reminds me of the "doctor killer" airplane. Forget the type of plane it was. But doctors were being killed in them because they could afford the high performance plane. Their new plane was capable of getting them into situations they weren't capable of handling. Maybe the eCCR is doing the same. The original was "The V-Tailed Doctor Killer" which was the V-35 Bonanza (Beech). Now it's a generic term for a high performnce single engine airplane. The "MCCR = 0 and ECCR = Lots" does just about say it all..... Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
(Offline)

4th February 2007, 04:37	#22 (permalink)
*ScubaDadMiami* Moderator Current Rebreather/s: Optima Other Rebreather/s: Join Date: Sep 2005 Location: Florida, USA Posts: 2,215	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Okay, let's break it down a little more (though I doubt there will be meaningful data to do it): How many eCCR deaths occured where the diver was flying manually above a lower set point? __________________ Howard Packer IANTD CCR Instructor Miami Beach, Florida CCRDiveTraining.com
(Offline)

4th February 2007, 04:40	#23 (permalink)
Gill Envy Shearwater Copis Divers Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,347	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Quote: (Originally Posted by silentscuba) Gill- No matter what you do with a pure MCCR you will only be adding more failure points if you try to blend an ECCR and a MCCR. Since it seems that some ECCR divers want the unit to be able to take care of them if they have a problem, the best idea that has come out that could be added to a MCCR is the "PARACHUTE SYSTEM". That idea came about to address safety of a diver having a problem and not being able to manage a minimum PO2. The "PARACHUTE SYSTEM" is set up to add O2 if the PO2 drops down to a certain setpoint, say .4. But, now you have added new electonics, fittings, batteries, solenoid etc. I feel that the "PARACHUTE SYSTEM" on a Constant Flow MCCR would be the closest to a blending of both types of rebreathers. As far as the depth ratings, most units can be upgraded to be able to handle most any depth that you want. Just my thoughts. Curt that is certainly an understandable perspective overall. I'm inclined to agree that a "parachute o2 injection system" would add more failure points in the most critical system, and perhaps even more importantly not engage the diver as thoroughly in the PO2 monitoring process since he/she would now feel confident that their screw up would not result in death. Correct me if I’m wrong, mCCR divers are relying on more and more electronics either by virtue of design or "add on's" as it is. The Copis for instance relies on electronics for PO2 monitoring and incorporates a HUD. So far it seems that a constant po2 computer or even two are a common addition to the mCCR mix. Complexity seems to be carefully embraced more and more in all areas except the life critical area o2 injection and po2 monitoring. That is why I’m questioning if the added complexity of all other components of an eCCR except the solenoid auto 02 injection system are really the issue. they may very well all be useful tools since they aren't related to po2 balance. In other words, they provide more benfits than risks. Auto injection of o2 seems to be the one major area that likely provides more risks than benefits under current design and or style of use(a change in style of use or design may change this down the road, but for now seems to be the likelyhood). I guess my point is that it may not be the Simple, in the "Keep it Simple Stupid" philosophy but the “Manual" o2 injection in mCCR that is the key. The added failure points may not turn out to be the determining factor, or the reliance on electronics per se but very specifically the reliance on electronics to balance the po2 and that may even come down to the way such a design allows a diver to become un-engaged in the process more than risk of malfunction. While it's true that mCCR's are simpler, it also seems true to me that they are only truly manual at the point that oxygen is needed to be added by the diver periodically, particularly on ascent. An mCCR with two constant po2 computers is complex (3 displays to monitor... and pricey), but remains simple in the way that seems to count the most. It's unintuitive that the added task loading of monitoring three screens and manual injection is outweighed by the apparent benefits of the constant flow orifice and "topping off" required by the diver. That is, IMHO, why so many folks making the switch from OC go directly to eCCR, because they feel that it's safer due to less task loading...that would be my wife and I. It seems that as time goes, more electronics are added on to mCCR's by manufacturers and that does not seem to be effecting mortality rate, at least not yet. In fact the addition of an electronic po2 monitor early on likely drastically reduced the fatality rates of early mCCR's. And now the Copis in particular has a HUD, this could be seen as added complexity as well. Where this leads me is: if the downsides of a constant/manually adjusted o2 flow system can be overcome by in design advancements, it seems compelling that leaving this one function out of an eCCR and in the hands AND brain of the diver may turn out to have a dramatic impact on fatality rates either by virtue of encouraging "safer" habits or by virtue of it being in some other way more reliable. Even if you loaded up the system with an Auto On switch, temp stick, co2 monitor, built in deco computer combined with the po2 monitor viewed by a primary and perhaps a secondary display, maybe even a totally independent constant po2 computer like a VR3 and an HUD...but incorporated a truly manual o2 injection system, i'm guessing the fatality rates of this style m/eCCR hybrid would match that of the mCCR (although i'm sure eventurally someone is going to die on an mCCR or this style hybrid eCCR just by virtue of odds). It seems to me that the trend is slowly happening, what you call it is immaterial; an electronic mCCR or a manual injection eCCR. It looks an awful lot like it's either actually "safer" or it instills "safer" habits to have manual o2 control regardless of what other components are electronic. Why the fatality rates are lower is debatable in the end, but the fact remains, and it's one of the few solid facts we have, fatality rates on mCCR's are much lower than eCCR's and I think it's worth trying to identify how eCCR's could be improved with this knowledge. anyone's thoughts are welcome. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°> Last edited by Gill Envy : 4th February 2007 at 04:52.
(Offline)

4th February 2007, 05:34	#24 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,487	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Quote: (Originally Posted by ScubaDadMiami) Okay, let's break it down a little more (though I doubt there will be meaningful data to do it): How many eCCR deaths occured where the diver was flying manually above a lower set point? All of them, unless you could prove otherwise. We are missing a lot of the general data from the incident, and you are looking for the needle... __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
(Offline)

4th February 2007, 06:25	#25 (permalink)
DonalWalsh Third Class Snorkeller Current Rebreather/s: Megalodon Other Rebreather/s: Evolution Join Date: Nov 2005 Location: Moving to London in Sept.....which way to the South Coast?? Posts: 133	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Quote: (Originally Posted by Mark Chase) KISS type MCCR deaths......None ECCR various units deaths.. Loads That about sums it up really. However i once told a friend and DIR diver that once DIR became mainstream dick heads would start diving DIR not because they really believed it but because they thought it was cool. Then the system will break down. Rightly or wrongly I believe a lot of divers moved to the Meg because the Inspo was seen as dangerous and the Megs image was one of superior design in every way. That didn't work I fear that divers will choose MCCR not because they 100% believe in the concept of being part of the unit but because of its safety record. Then Darwin will kick in and we will have a spat of MCCR deaths. On the other hand its 11.40pm and I am a bit cheesed off so maybe i am being negative about the whole thing ATB Mark Chase Nope- you're not. You hit about three nails on the head there. __________________ "Anybody can be a bum. All you need is the right girl, the right bar, and the right friends. They will see you off. They will christen your dumpster for you. "- Bill Hicks
(Offline)

4th February 2007, 14:26	#26 (permalink)
bletso An independent diver. Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: May 2006 Location: Louisville, KY, USA Posts: 263	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates I think you all are missing the boat! Once you add a "parachute system" to an MCCR, it is no longer a true manual system. It is a very simple ECCR. It will make or at least attemp to keep you alive. In a true MCCR, the only thing that keeps you alive is Dave Sutton's "Thumb/brain connection" (TBC). Use any type computer or monitoring system for PO2, deco, CO2 you want, but the plain SIMPLE fact is YOU keep YOU alive via the TBC. I choose not to use a HUD because I use two primary displays. If I mounted them where I could see them all the time, they would become distracting, perhaps to the point of not seeing them. (It's a basic human reaction. Familiarity breeds contemp.) A HUD is normally a secondary display. I don't use them!!!!! (Secondary displays) Keeping all that in mind, would I be able to do a 100MSW dive? Yes, because I use a high IP and a small orifice. But 100 MSW is my design's limit. It actually is about the limit for pressure of the orifice placed by the manufacturer. If I wanted to go deeper, then I would have to go to an ECCR system. But how many of us dive deeper? I do not. Most of my venues are less than 70 MSW and the vast majority are 50 MSW or less. FYI, I do a lot of shallower dives on my MCCR. I don't add O2 on ascent because I don't have to. I have maintained a proper PO2 during the dive. I do a diluent flush before ascent. (habit) If its a deco dive, and many are I do my off board gas switches at the appropriate depths,do the purges and voila, it works. Dale
(Offline)

4th February 2007, 17:07	#27 (permalink)
Gill Envy Shearwater Copis Divers Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,347	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Quote: (Originally Posted by bletso) I think you all are missing the boat! Once you add a "parachute system" to an MCCR, it is no longer a true manual system. It is a very simple ECCR.... Dale Dale, I think your perspective is certainly understandable and it may turn out to be the most accurate. However, the thing that perplexes me is that "parachutes" are already being added on a regular basis to mCCR's with no change in mortality rates... po2 monitor, HUD, Multiple deco computers with the specific exception of an automatic o2 injection system. It's very tempting to me to therefore conclude that is is not overall complexity that is the deciding factor but the manual addition of o2 and monitoring of po2 by the diver. It may also be that the parachutes that are being added are mostly independent of one another. If composed of totally independent systems, it would seem that a manual injection eCCR would likely prove just as safe as modern day mCCR's...that is until the risks of auto injection systems, either due to style of use or failure points are overcome by advancements. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
(Offline)

4th February 2007, 17:13	#28 (permalink)
Dutchy Rene Warries Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Nieuwegein (The Netherlands) Posts: 843	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Being on top of your condition is what keeps you alive I think. Adding a single HUD is about the dumbest design decission possible. Do you really add three cells and separate displays only to forget all about them because you start relying on a single hud? HUD = Electronics. I hate electronics especially every component that apears to be electronincs but is in reality embedded software. And we all know software is less tangiable than mechanics so failures aren't as easily spotted. But I have a watchdog. Yeah right. Does your watchdog do something when your AD converter failed? I don't think so and on top watchdogs are programmed as well. I've seen failures in other life sustaining equipment. Luckily that was medical equipment scrutenized in a factory acceptance test after thousands of hours of testing in a far more rigid regime. The botom line. If you want to use a HUD you should be able to REALLY rely on them, making them primaries. In fact that means you need to have two. My advice would be to use two from different vendors so as to rule out identical errors in them. If I'm right and failing equipment IS a factor then the the majority of future mccr fatalities will be amongst HUD users rather than mere display users. Without saying it goes that three displays on a single piece of electronics gives one the same potential problems. I love well designed equipment. Safety is not only in the number of cells but also in what you do with that info. __________________ = This post is environmentally friendly. It is composed of 100% recycled electrons only. =
(Online)

4th February 2007, 19:20	#29 (permalink)
silentscuba rEvo CCR Driver Current Rebreather/s: Classic Kiss rEvo Other Rebreather/s: Inspiration Classic rEvo Join Date: Jun 2005 Location: Mill Creek, WA USA Posts: 612	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Quote: (Originally Posted by Dutchy) Being on top of your condition is what keeps you alive I think. Adding a single HUD is about the dumbest design decission possible. Do you really add three cells and separate displays only to forget all about them because you start relying on a single hud? HUD = Electronics. I hate electronics especially every component that apears to be electronincs but is in reality embedded software. And we all know software is less tangiable than mechanics so failures aren't as easily spotted. But I have a watchdog. Yeah right. Does your watchdog do something when your AD converter failed? I don't think so and on top watchdogs are programmed as well. I've seen failures in other life sustaining equipment. Luckily that was medical equipment scrutenized in a factory acceptance test after thousands of hours of testing in a far more rigid regime. The botom line. If you want to use a HUD you should be able to REALLY rely on them, making them primaries. In fact that means you need to have two. My advice would be to use two from different vendors so as to rule out identical errors in them. If I'm right and failing equipment IS a factor then the the majority of future mccr fatalities will be amongst HUD users rather than mere display users. Without saying it goes that three displays on a single piece of electronics gives one the same potential problems. I love well designed equipment. Safety is not only in the number of cells but also in what you do with that info. I dive a KISS Classic. I have an integrated Shearwater and a HUD from a different manufacturer. They are both independent from each other except for the 3 O2 cells. I use my HUD as a tool to keep my O2 swing to a minimum and to give me a quicker indication of a problem. I do not use it as my primary O2 indicator. I feel that it does increase my safety and helps me keep a more constant PO2. If my primary does fail, the HUD gives me a reliable backup to help get me back out of the water. I love my HUD and my Shearwater __________________ Curt McNamee rEvo CCR Diver KISS CCR Diver www.silentscuba.com
(Offline)

4th February 2007, 20:16	#30 (permalink)
Dutchy Rene Warries Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Nieuwegein (The Netherlands) Posts: 843	Re: Differences between eCCR’s and mCCR’s design that may effect mortality rates Quote: (Originally Posted by silentscuba) I dive a KISS Classic. I have an integrated Shearwater and a HUD from a different manufacturer. They are both independent from each other except for the 3 O2 cells. I use my HUD as a tool to keep my O2 swing to a minimum and to give me a quicker indication of a problem. I do not use it as my primary O2 indicator. I feel that it does increase my safety and helps me keep a more constant PO2. If my primary does fail, the HUD gives me a reliable backup to help get me back out of the water. I love my HUD and my Shearwater You got the idea. Imho one of theproblems is that many don't know the design of their unit and consequently they don't know whether they are putting their eggs in the same basket or not. Some stuff in the market looks redundant but isn't. The way you did it makes sense with your attitude. I myself would - over time - be tempted to trust the HUD and forget about the primary... __________________ = This post is environmentally friendly. It is composed of 100% recycled electrons only. =
(Online)

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