mCCR and zero viz exit

**Gill Envy** · 2nd April 2008, 15:40

Nah, I just own stock in Progresso.

Quote: (Originally Posted by PCDiver)

Gill is definitely on a crusade against eCCRs

.

Mdemon · 2nd April 2008, 17:05

Quote: (Originally Posted by Lizardland)

I've become very uncomfortable with my Shearwater replacing the stock handsets as the data is processed and there is no "unprocessed" confirmation.

Blimey! Can do you a nice set of Napier's Bones if you want, Guv'nor?!

OK, they crash, they reset without warning, they die miserably quickly, but the one thing computers are very good at is maths. Surely as long as the thing hasn't frozen you trust them enough to multipy mV to get PO2??? (No Pentium floating point issues in a Shearwater as far as I'm aware!)

Are you upgrading your Rebreather then?

Quote: (Originally Posted by sfldiver)

Remember, the HUD is controlled by the secondary, so if that goes, so does the HUD!

On your machine!

Not so the independent HUDs I mentioned. I like the Deep Pursuit mentality whereby everything is completely independent. The Vision should have been, apparently isn't. BIG mistake - the true advantage with HUDs comes from their separation from the PO2 controllers.

Quote: (Originally Posted by sfldiver)

But realistically, the odds of your primary and secondary shutting down at the same time is pretty slim! For that to happen, Murphy would really have to be after your a_s! However, I do assume the possibity of that happenning exists, which is why I spent so much $$ on adding the VR3 with the 4th cell - Peace of mind!!!!

I totally agree that the odds are very slim. But possible if you consider they share wires and solenoids. I also totally agree with the peace of mind that
4th cell monitoring gives. If not VR£ then some other form of monitoring like maybe a HUD...

Mark Chase · 2nd April 2008, 18:20

Quote:

I've become very uncomfortable with my Shearwater replacing the stock handsets as the data is processed and there is no "unprocessed" confirmation. OK, it has a mV display but it's still a processed number and is still going through the same processor as the PO2 display

I dont understand this?

I have a milivolt display and a PP02 display on my Shearwater but on my KISS displays i only have a PP02 display?

If the KISS only displays PP02 it that information not "Processed"

How is the data procesed on the Shearwater before it is displayed as milivolts?

I asumed MV was just MV???

I found this an advantage on both the Shearwater and the Hammer Head displays.

ATB

Mark

David Pye · 2nd April 2008, 19:10

Quote: (Originally Posted by Mark Chase)

I dont understand this?

I have a milivolt display and a PP02 display on my Shearwater but on my KISS displays i only have a PP02 display?

If the KISS only displays PP02 it that information not "Processed"

How is the data procesed on the Shearwater before it is displayed as milivolts?

I asumed MV was just MV???

I found this an advantage on both the Shearwater and the Hammer Head displays.

ATB

Mark

The KISS displays are just millivolt-meters with a calibration pot, so while they don't display mV, the information they display is simply an offset rather than something that a processor (as in the electronic sense) has performed mathematical calculations on. The KISS display doesn't do any calculations to produce PO2 from mV, it is simply done by an analogue circuit, which cannot hang/crash, as it doesn't have anything to hang

I have a Delta-P URM, and am also unhappy that the info as displayed on the VR3 (and that the VR3 uses to illuminate the HUD) is processed, as on occasion, if the VR3 hangs, so do the PO2 readings on its' screen. Also, they don't update in real time, so it takes a few seconds of observing them to figure out whether they are moving or not. The other thing is its' annoying habit of turning itself off during the wait on the boat, once the VR3 gets fed up with hanging around.

The Delta-P secondary display is almost EXACTLY what the original Jetsam KISS displays should have been. They are watertight, simple like the original kiss ones, can be calibrated without breaking the watertight seal, have a sensible battery and have a button to get them to display mV. Their two weaknesses imho are that they are a pendant ( I prefer wrist mounted), have less redundancy (1 battery, 1cable and 1 case) and that they turn off very quickly to conserve battery (as they are designed to be secondaries.

But I'm hard to please.. If the original Jetsam displays hadn't been so dodgy in terms of leaks....

Sigh...

David

lizardland · 2nd April 2008, 19:34

Quote: (Originally Posted by Mark Chase)

I dont understand this?

I have a milivolt display and a PP02 display on my Shearwater but on my KISS displays i only have a PP02 display?

If the KISS only displays PP02 it that information not "Processed"

How is the data procesed on the Shearwater before it is displayed as milivolts?

I asumed MV was just MV???

I found this an advantage on both the Shearwater and the Hammer Head displays.

ATB

Mark

The data going to the Shearwater is going to through some sort of digital processing before it is displayed. The mV, even though is raw data, is still having to go through some sort of processing, it's the same piece of data just being shown in a different format. It isn't verifying anything, it's the same data shown in a different way. If my display is displaying 1.00 then I might wonder if this is correct and switch to the mV reading. Aha... it's reading 48mV... that sounds near enough for a 1.00 PO2! But it's a false reassurance, it's still that same signal going through that same processor but shown in a different format.

The KISS display is essentially unprocessed. It takes the raw millivoltage and displays that. By setting the calibration pot all you are doing is moving the display range forwards and backwards along a sliding scale from 0-199. The cells are outputting, say 10-50mV at the surface, adjusting the pot just makes the starting point 20 instead of 10. The decimal point is preset and doesn't come into it. OK, there is some processing to get it on the display but it is an extremely basic circuit designed for the process industry which (I would hope) would be fault tolerant to industrial standards. Plus you've got three of them. OK, they are monitoring different things but that's what your brain is for. Compare the readings and come to a decision.

The Shearwater has taken me out of that loop, it is letting me see what it is wanting me to see, and it's processing it all in one place. For my philosophy, that's a bad thing and I'm not comfortable with no alternative way of verifying what is on my display. The triple independant display goes a lot further to do that, I have three individual systems that I can make a judgement on. It's not bombproof but I prefer it to an unverifiable single display. I could add a HUD but if I have a "processed" display then I want something unprocessed that puts me right in the middle of what is happening.

That's just my philosophy, other people may or may not be as uncomfortable in that approach as I am. I'm not saying it's good or bad, it's what I'm comfortable with.

Cheers,

Stuart

Mark Chase · 2nd April 2008, 20:41

Thanks, i didnt know that. i asumed the MV data on the shearwater was raw data.

ATB

Mark

silent running · 2nd April 2008, 21:23

Quote: (Originally Posted by sfldiver)

I'm in no way saying that the manner in which I monitor my handsets/PO2 is the best way, I was merely mentioning what habits I have formed and the reasons why I developed those habits. Furthermore, I see no problem with monitoring my tts frequently throughout the dive, especially since it doubles as an opportunity to view all three sensors on my primary handset, especially in light of the fact that my buddy and I often plan our dives to leave the bottom when we have reached a set tts. As I previously indicated, some of my habits come from my tech days. I was doing lots of deeper diving back in the early nineties, when divin deep on air was commonplace - Since narcosis was a factor always looming over your head on deep air diving, checking your gauges frequently was one method of countering those effects. So checking my gauges often is a tough habit to break.

Sure sfld, I understand. If I was diving deep air, I'd also be a little paranoid about time, deco, etc.. I was suggesting more HUD and less checking of the handsets as a way to better enjoy the dive. Me, I enjoy looking at the scenery, not looking at stuff on my wrist like I'm waiting for a late bus.

Quote: (Originally Posted by sfldiver)

I agree that the use of the HUD as the primary method for monitoring one's PO2 is the most efficient method and that is something that I am working on relying more, but in the interim, I still don't see the downside in checking my gauges (tts and po2) often, other than it not being the most efficient method, but it is more conservative, because I am looking at all three sensors often. If you lose a sensor, the HUD may not immediately reflect that fact, because of the voting logic. I also check my VR3 (tts and 4th cell po2) often.

As above, there's no downside to looking at your gages a lot, except for having to take your eyes off whatever it is you spent all that money to look at in 70m of water.

As for sensors being voted out, the Prism HUD tells you when 1 or 2 sensors are voted out as well as above/below SP and when your power is low. IMHO, all HUDs should tell you at least this much, especially whether all 3 sensors are tracking together...

**Gill Envy** · 3rd April 2008, 00:24

Quote: (Originally Posted by PCDiver)

Gill is definitely on a crusade against eCCRs

.

on a more seriouse note, my apologies if the irony of all this gets me a little worked up and evangelical sounding. If I am on some kind of crusade in this thread it would be to counter unfounded fears about mCCR's with a little reality check. I have no qualms about people loving their eCCR's except when they start claiming that they are "safer". their are lots of valid justifications for diving eCCR's, but the "safer" claim is just not one of them, IMHO.

I hear accounts of more and more people doing all sorts of diving with mCCR's and I just don't get where all the counter safety concerns about mCCR's are coming from, certainly not incidences and certainly not consistent with my personal experience.

Paradoxically, assuming eCCR's are more dangerous, or however you want to put it, maybe one of the keys to reducing complacency and lowering the high incident rate that is actually associated with them.

mattmexico · 3rd April 2008, 00:43

yo

Its hard to keep up with all the reading, hardly have the time as I am back cave diving ... mCCR to think about it some more and let it settle ... as the silt stirred up today by my student ... who is diving eCCR ...

Please all keep it up .. so I have something to read after coming from the dark side and think about when drifting in the inky darkness ...

I certainly feel that the thread helped me to identify different angles and aspects I have not thought or dreamt off before ...

great stuff !!

Matt

Shawn · 3rd April 2008, 02:34

Ok I have tried to read all of the posts, but I may have missed something...

At either rate when I trained on the Meg eCCR it was the same thing every dive...

Set your set point and then fly the Meg manually, if you become distracted the solenoid will fire, and this should serve as a warning to check your PO2 then continue to fly the unit manually.

I like the fact that the Primary, secondary, and hud are all separate...but if either of my hand sets fail I'm turning the dive...if they both fail I'm bailing out.

As for the zero vis stuff...I have been diving in the midwest for several years and in the worst conditions I have still been able to read my display by holding it against my mask. I know not the ideal situation, but it works!

On ascent even with the solenoid firing automatically on a 3 sec delay the loop could still go hypoxic if your ascending too fast...At either rate I personally would have bailed out, then got back on the loop when i could read the displays.

This was a really good post, It made me thinnk about things that i may have never thought about until I was in your shoes and who knows what decisions are being made until it's too late. I'm giving you some GREEN!

Thanks

2nd April 2008, 15:40	#81 (permalink)
Gill Envy Shearwater Copis Divers Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,326	Re: mCCR and zero viz exit Nah, I just own stock in Progresso. Quote: (Originally Posted by PCDiver) Gill is definitely on a crusade against eCCRs . __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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2nd April 2008, 17:05	#82 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,931	Re: mCCR and zero viz exit Quote: (Originally Posted by Lizardland) I've become very uncomfortable with my Shearwater replacing the stock handsets as the data is processed and there is no "unprocessed" confirmation. Blimey! Can do you a nice set of Napier's Bones if you want, Guv'nor?! OK, they crash, they reset without warning, they die miserably quickly, but the one thing computers are very good at is maths. Surely as long as the thing hasn't frozen you trust them enough to multipy mV to get PO2??? (No Pentium floating point issues in a Shearwater as far as I'm aware!) Are you upgrading your Rebreather then? Quote: (Originally Posted by sfldiver) Remember, the HUD is controlled by the secondary, so if that goes, so does the HUD! On your machine! Not so the independent HUDs I mentioned. I like the Deep Pursuit mentality whereby everything is completely independent. The Vision should have been, apparently isn't. BIG mistake - the true advantage with HUDs comes from their separation from the PO2 controllers. Quote: (Originally Posted by sfldiver) But realistically, the odds of your primary and secondary shutting down at the same time is pretty slim! For that to happen, Murphy would really have to be after your a_s! However, I do assume the possibity of that happenning exists, which is why I spent so much $$ on adding the VR3 with the 4th cell - Peace of mind!!!! I totally agree that the odds are very slim. But possible if you consider they share wires and solenoids. I also totally agree with the peace of mind that 4th cell monitoring gives. If not VR£ then some other form of monitoring like maybe a HUD... __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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2nd April 2008, 18:20	#83 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,693	Re: mCCR and zero viz exit Quote: I've become very uncomfortable with my Shearwater replacing the stock handsets as the data is processed and there is no "unprocessed" confirmation. OK, it has a mV display but it's still a processed number and is still going through the same processor as the PO2 display I dont understand this? I have a milivolt display and a PP02 display on my Shearwater but on my KISS displays i only have a PP02 display? If the KISS only displays PP02 it that information not "Processed" How is the data procesed on the Shearwater before it is displayed as milivolts? I asumed MV was just MV??? I found this an advantage on both the Shearwater and the Hammer Head displays. ATB Mark __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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2nd April 2008, 19:10	#84 (permalink)
David Pye CK#69 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: May 2006 Location: Newcastle Upon Tyne Posts: 174	Re: mCCR and zero viz exit Quote: (Originally Posted by Mark Chase) I dont understand this? I have a milivolt display and a PP02 display on my Shearwater but on my KISS displays i only have a PP02 display? If the KISS only displays PP02 it that information not "Processed" How is the data procesed on the Shearwater before it is displayed as milivolts? I asumed MV was just MV??? I found this an advantage on both the Shearwater and the Hammer Head displays. ATB Mark The KISS displays are just millivolt-meters with a calibration pot, so while they don't display mV, the information they display is simply an offset rather than something that a processor (as in the electronic sense) has performed mathematical calculations on. The KISS display doesn't do any calculations to produce PO2 from mV, it is simply done by an analogue circuit, which cannot hang/crash, as it doesn't have anything to hang I have a Delta-P URM, and am also unhappy that the info as displayed on the VR3 (and that the VR3 uses to illuminate the HUD) is processed, as on occasion, if the VR3 hangs, so do the PO2 readings on its' screen. Also, they don't update in real time, so it takes a few seconds of observing them to figure out whether they are moving or not. The other thing is its' annoying habit of turning itself off during the wait on the boat, once the VR3 gets fed up with hanging around. The Delta-P secondary display is almost EXACTLY what the original Jetsam KISS displays should have been. They are watertight, simple like the original kiss ones, can be calibrated without breaking the watertight seal, have a sensible battery and have a button to get them to display mV. Their two weaknesses imho are that they are a pendant ( I prefer wrist mounted), have less redundancy (1 battery, 1cable and 1 case) and that they turn off very quickly to conserve battery (as they are designed to be secondaries. But I'm hard to please.. If the original Jetsam displays hadn't been so dodgy in terms of leaks.... Sigh... David
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2nd April 2008, 19:34	#85 (permalink)
lizardland Yak Current Rebreather/s: MK 15.X Home Build Other Rebreather/s: Classic Kiss Home Build Join Date: Mar 2005 Location: North... Posts: 1,302	Re: mCCR and zero viz exit Quote: (Originally Posted by Mark Chase) I dont understand this? I have a milivolt display and a PP02 display on my Shearwater but on my KISS displays i only have a PP02 display? If the KISS only displays PP02 it that information not "Processed" How is the data procesed on the Shearwater before it is displayed as milivolts? I asumed MV was just MV??? I found this an advantage on both the Shearwater and the Hammer Head displays. ATB Mark The data going to the Shearwater is going to through some sort of digital processing before it is displayed. The mV, even though is raw data, is still having to go through some sort of processing, it's the same piece of data just being shown in a different format. It isn't verifying anything, it's the same data shown in a different way. If my display is displaying 1.00 then I might wonder if this is correct and switch to the mV reading. Aha... it's reading 48mV... that sounds near enough for a 1.00 PO2! But it's a false reassurance, it's still that same signal going through that same processor but shown in a different format. The KISS display is essentially unprocessed. It takes the raw millivoltage and displays that. By setting the calibration pot all you are doing is moving the display range forwards and backwards along a sliding scale from 0-199. The cells are outputting, say 10-50mV at the surface, adjusting the pot just makes the starting point 20 instead of 10. The decimal point is preset and doesn't come into it. OK, there is some processing to get it on the display but it is an extremely basic circuit designed for the process industry which (I would hope) would be fault tolerant to industrial standards. Plus you've got three of them. OK, they are monitoring different things but that's what your brain is for. Compare the readings and come to a decision. The Shearwater has taken me out of that loop, it is letting me see what it is wanting me to see, and it's processing it all in one place. For my philosophy, that's a bad thing and I'm not comfortable with no alternative way of verifying what is on my display. The triple independant display goes a lot further to do that, I have three individual systems that I can make a judgement on. It's not bombproof but I prefer it to an unverifiable single display. I could add a HUD but if I have a "processed" display then I want something unprocessed that puts me right in the middle of what is happening. That's just my philosophy, other people may or may not be as uncomfortable in that approach as I am. I'm not saying it's good or bad, it's what I'm comfortable with. Cheers, Stuart __________________ Can you imagine drifting along in the sea with your mouth open and a load of f***ing plankton going in? You'd like it, would you? www.westons-cider.co.uk Azerbaijani Association of Technical Divers Publicity Officer and Goat Wrangler
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2nd April 2008, 20:41	#86 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,693	Re: mCCR and zero viz exit Thanks, i didnt know that. i asumed the MV data on the shearwater was raw data. ATB Mark __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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2nd April 2008, 21:23	#87 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,836	Re: mCCR and zero viz exit Quote: (Originally Posted by sfldiver) I'm in no way saying that the manner in which I monitor my handsets/PO2 is the best way, I was merely mentioning what habits I have formed and the reasons why I developed those habits. Furthermore, I see no problem with monitoring my tts frequently throughout the dive, especially since it doubles as an opportunity to view all three sensors on my primary handset, especially in light of the fact that my buddy and I often plan our dives to leave the bottom when we have reached a set tts. As I previously indicated, some of my habits come from my tech days. I was doing lots of deeper diving back in the early nineties, when divin deep on air was commonplace - Since narcosis was a factor always looming over your head on deep air diving, checking your gauges frequently was one method of countering those effects. So checking my gauges often is a tough habit to break. Sure sfld, I understand. If I was diving deep air, I'd also be a little paranoid about time, deco, etc.. I was suggesting more HUD and less checking of the handsets as a way to better enjoy the dive. Me, I enjoy looking at the scenery, not looking at stuff on my wrist like I'm waiting for a late bus. Quote: (Originally Posted by sfldiver) I agree that the use of the HUD as the primary method for monitoring one's PO2 is the most efficient method and that is something that I am working on relying more, but in the interim, I still don't see the downside in checking my gauges (tts and po2) often, other than it not being the most efficient method, but it is more conservative, because I am looking at all three sensors often. If you lose a sensor, the HUD may not immediately reflect that fact, because of the voting logic. I also check my VR3 (tts and 4th cell po2) often. As above, there's no downside to looking at your gages a lot, except for having to take your eyes off whatever it is you spent all that money to look at in 70m of water. As for sensors being voted out, the Prism HUD tells you when 1 or 2 sensors are voted out as well as above/below SP and when your power is low. IMHO, all HUDs should tell you at least this much, especially whether all 3 sensors are tracking together...
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3rd April 2008, 00:24	#88 (permalink)
Gill Envy Shearwater Copis Divers Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,326	Re: mCCR and zero viz exit Quote: (Originally Posted by PCDiver) Gill is definitely on a crusade against eCCRs . on a more seriouse note, my apologies if the irony of all this gets me a little worked up and evangelical sounding. If I am on some kind of crusade in this thread it would be to counter unfounded fears about mCCR's with a little reality check. I have no qualms about people loving their eCCR's except when they start claiming that they are "safer". their are lots of valid justifications for diving eCCR's, but the "safer" claim is just not one of them, IMHO. I hear accounts of more and more people doing all sorts of diving with mCCR's and I just don't get where all the counter safety concerns about mCCR's are coming from, certainly not incidences and certainly not consistent with my personal experience. Paradoxically, assuming eCCR's are more dangerous, or however you want to put it, maybe one of the keys to reducing complacency and lowering the high incident rate that is actually associated with them. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°> Last edited by Gill Envy : 3rd April 2008 at 18:13.
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3rd April 2008, 00:43	#89 (permalink)
mattmexico Rebreather World Writer Current Rebreather/s: Megalodon Classic Kiss Optima RB80 / Clone Other Rebreather/s: Inspiration Classic Evolution Prism Topaz Sport Kiss RB80 / Clone Join Date: Aug 2005 Location: Mexico, Q.Roo, Playa del Carmen Posts: 764	Re: mCCR and zero viz exit yo Its hard to keep up with all the reading, hardly have the time as I am back cave diving ... mCCR to think about it some more and let it settle ... as the silt stirred up today by my student ... who is diving eCCR ... Please all keep it up .. so I have something to read after coming from the dark side and think about when drifting in the inky darkness ... I certainly feel that the thread helped me to identify different angles and aspects I have not thought or dreamt off before ... great stuff !! Matt __________________ N 20' 37.617' W 87' 04.693' www.andreaswmatthes.com
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3rd April 2008, 02:34	#90 (permalink)
Shawn Custom Title Allowed! Current Rebreather/s: Megalodon Other CCR RB80 / Clone Other Rebreather/s: Other CCR RB80 / Clone Join Date: Oct 2007 Location: Kansas City Kansas Posts: 142	Re: mCCR and zero viz exit Ok I have tried to read all of the posts, but I may have missed something... At either rate when I trained on the Meg eCCR it was the same thing every dive... Set your set point and then fly the Meg manually, if you become distracted the solenoid will fire, and this should serve as a warning to check your PO2 then continue to fly the unit manually. I like the fact that the Primary, secondary, and hud are all separate...but if either of my hand sets fail I'm turning the dive...if they both fail I'm bailing out. As for the zero vis stuff...I have been diving in the midwest for several years and in the worst conditions I have still been able to read my display by holding it against my mask. I know not the ideal situation, but it works! On ascent even with the solenoid firing automatically on a 3 sec delay the loop could still go hypoxic if your ascending too fast...At either rate I personally would have bailed out, then got back on the loop when i could read the displays. This was a really good post, It made me thinnk about things that i may have never thought about until I was in your shoes and who knows what decisions are being made until it's too late. I'm giving you some GREEN! Thanks __________________ WWW.DiveOne.net
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