Hybrid Rebreathers

OceanOpportunity · 21st April 2008, 03:13

I'm still on the fence about the logic behind using a hybrid O2 injection method. Having been originally trained on a variety of eCCR's, and having switched to mCCR (largely in an effort to simplify my rig and reduce failure points), I still look at this as unnecessarily complex...I am open to being swayed otherwise.

When diving, or even using, anything that is electronic/computer controlled the system earns our confidence by our recognizing that it is functioning properly at easily measured and recognized intervals. For example, in some recent discussion on HUDs, most agreed that at least one LED should blink continuously, rather than stay lit as we know that the HUD is responsive to the cells. In the case of an eCCR, during a dive, much of my confidence in an eCCR system is by hearing the solenoid firing on regular intervals. After a while, it's like clockwork. You should be checking your handsets regularly anyway, but in the event that you arent hearing a solenoid firing, its a safe bet to assume that it isnt working, and you need another means to get O2 in to the unit.

On all eCCRs, solenoid is our primary means of injecting O2, a manual add button is the backup.

Now, on mCCR, we rely on the orifice with routine/consistent manual injections. This is a similar pattern of recognition, just like hearing the solenoid fire, that ensures things are working properly. Orifice fails somehow and we are still injecting manually, just more regularly, to maintain a desired setpoint.

Having said this, and pointing out 'patterns of recognition' in both methods, I feel like a hybrid O2 injection method, depending on how its dived, takes away the need for an individual to recognize these patterns, and gain confidence in the system. Assume we dive mCCR as our primary, with a solenoid backing us up. The solenoid would never fire, unless we weren't doing our job with manual injections at all. Even at that, the O2 decay time to get there would be quite lengthy. Given that the solenoid hasn't been regularly firing the whole dive, I'm not convinced that I would then depend on it in a pinch, and even at that, why bother if your manually adding anyway? Conversely, if we dive eCCR/solenoid as primary with an orifice as secondary, all that is happening is prolonging automatic injections. Why bother? I'd rather know that my solenoid is firing, and with a recognizable frequency.

I made the switch to mCCR to simplify things after having a few troubles with various electronics/solenoids. I do the same dives, and feel like I've become a better CCR diver since mCCR forces those patterns to become part of my dive, hence I've earned a better appreciation for what is going on in my loop.

If, and thats a big IF, I saw the utility value in a hybrid approach, it would be for very extended range diving, with both systems completely isolated from one another. In this case, I would dive eCCR/solenoid mode until it failed, at which point I would flip a valve and allow my orifice to trickle. This simply assists in what could be a laborious tasks of manually adding to come back home when very far away.

Using both methods together, IMO, unnecessarily complicates what should be a very simple and recognizeable mode of diving.

Definitely interested in being taken to task on my way of thinking here...

PnL · 21st April 2008, 04:12

Hi Mike,

For me, the benefit of having a hybrid system is the ability to set my rig to the type of diving that I will be doing. For general diving, and perhaps for dives where I may be more task loaded then usual, I would dive my rig in mCCR mode with the controller as a silent backup system.

For a dive where I know that I will be task loaded (e.g., video), I can dive the rig in full eCCR mode. This also removes the depth limitations that a CMF orifice places on an mCCR unit and is one way of getting deeper without much fiddling on the rig.

This is the main reason I think a hybrid system is nice. I dive a fully mCCR rig (rEvo) right now and like the fact that its a mCCR and "simple", as you state. But having the option to easily covert to a parachute system (hybrid), or full eCCR can have its advantages depending on the dive.

This is, of course, MHO.

Regards,
Paul

**Gill Envy** · 21st April 2008, 06:11

Quote: (Originally Posted by dave t)

slightly off thread but my belief is that the reason why MCCr's have a good safety record is the "mindset" they instill in the diver. Adding auto functions may deteriorate that mindset!

Dave

That is my concern, though I doubt that comes as a surprise

. Given the choice between manual injection and auto... I'd go with auto... so I don't give myself the choice.

I also found Michael's post very well spoken... greened.

the hybrid approach is an interesting idea though. It may prove a step forward for eCCR's but not sure about the reverse. Also curious about hybrid needle valve eCCR's... anyone trying that?

One thing is almost irrefutable, having the manual option on remote trips will be very convenient in the case of a melt down in the injection system... that would surely boost reliability for eCCR's.

Verifying that both systems work in pre-dive mode would be key. A flow meter for the orifice and A dilluent flush for the solenoid aught to do it.

Stephane · 21st April 2008, 06:21

Hello Gill,

Quote:

Verifying that both systems work in pre-dive mode would be key. A flow meter for the orifice and A dilluent flush for the solenoid aught to do it.

A flow meter before each dive? No need! Just verify that there is a flow of gas.
Diluent flush for the solenoid? It delivers O2 ...

J. V. · 21st April 2008, 07:44

Why I use an hybrid rEvo
Cause with an hybrid I do just what I want to do.
- I want a mCCR cause the dive profil is yoyo or to preserve solenoïd battery? I put the set point on 0.5
- I need my two hands to install a line or something like that? I put the set point on 1.2 or more.
- I want to dive deeper than the fixed IP limit? I just take off a bolt and put on an other.
- My beautiful electronic is out and need to go back to the manufacturer? I continue to dive in mCCR.
- The O2 orifice is clogged? I continue to dive in eCCR mode.
Etc.
In fact, I've not a rebreather, I've two rebreather.

Ben Field · 21st April 2008, 08:05

I'm currently of the opinion that Hybrids in come form represent the future for recreational units- if a balance can be found to force people into the MCCR paranoid operation mode and not relying on the electronics- so its there as just a parachute to boost PPO2 when you've really missed something (somewhere below 0.5?)

A couple of elements are IMO stumbling blocks-
1. First stage- MCCR's require (generally) high but fixed IP, whereas Solenoids require low but balanced IP. Recreational units would be overcomplicated with twin O2 tanks, even H valves and two regs- I think that a Dual IP output reg or similar system is required before this is viable for the majority.

2. Battery Life. On MCCR's we are used to massive battery life 6-12months, on ECCR the battery life is pitiful due to the Solenoid, 20-40hours top I believe> (1 dive if you have certain units!)
With a Hybrid where the MCCR operation is effectively extending the Solenoid batteries life how do you predict/guard against it failing? I could dive 4months on almost purely MCCR apart from testing the solenoid then when an emergancy happens (CBL a buddy for example) and I rely on the Parachute/solenoid side of my system, only to find the 4month old battery can't run the ECCR part sufficently...

Maybe the ECCR should be wind up?

OceanOpportunity · 22nd April 2008, 01:31

This perspective I can greatly appreciate, and it makes alot of sense:

Quote: (Originally Posted by J. V.)

In fact, I've not a rebreather, I've two rebreather.

The ability to switch one platform between O2 injection modes does solve alot by way of mission specific considerations. Then of course, we EITHER dive mCCR OR eCCR.

I'm still not buying any logic on utilizing both methods synergistically. I will admit that I went through a mindset just over a year ago, when I first switched to mCCR, that I wanted to see a 'parachute' in effect. The more I've considered what this would do for me, the less I like the idea. Again, when using electronics, not simply as a monitoring device, but as a controller of a specific mechanism, I am going to look for some recognizeable pattern such that I know it is functioning properly. When used as a parachute, waiting an hour or more into the dive for the thing to fire does not instill any additional confidence or assurance. IMO, it does the opposite...I'd be so paranoid that the thing wouldnt work when needed that I'd be paying EXTRA close attention to my monitoring devices and manual injections...I'd never need the parachute. As they say, there's two ways to skin a cat

is there any evidence based logic to support the benefits of a hybrid system (both modes synergistically)..any personal experiences where this wouldve been beneficial?

As a point of clarification...I think that by offering the two modes as an option for a unit is a brilliant move by the mfg's. It does give the end user two rigs for the price of one (+/-). I jsut dont buy utilization of both modes at the same time.

mik · 22nd April 2008, 03:08

Quote: (Originally Posted by OceanOpportunity)

is there any evidence based logic to support the benefits of a hybrid system (both modes synergistically)..any personal experiences where this wouldve been beneficial?

As a point of clarification...I think that by offering the two modes as an option for a unit is a brilliant move by the mfg's. It does give the end user two rigs for the price of one (+/-). I jsut dont buy utilization of both modes at the same time.

How about this incident?

PnL · 22nd April 2008, 04:07

Quote: (Originally Posted by OceanOpportunity)

When used as a parachute, waiting an hour or more into the dive for the thing to fire does not instill any additional confidence or assurance. IMO, it does the opposite...I'd be so paranoid that the thing wouldnt work when needed that I'd be paying EXTRA close attention to my monitoring devices and manual injections...I'd never need the parachute.

Mike,

Is there any evidence to suggest that the solenoid would not fire in "parachute" mode when you need it? I've never had a solenoid on my rig so I'm curious to what the failure rate of eCCR's are such that this is a real concern during a dive, especially if you are doing your predives and the solenoid is firing properly.

For me, the "parachute" system is purely backup - I am still the one responsible for maintaining my ppO2 and I always will be when flying manual, I don't think there are two ways about it. But if I were to pass out, or something else were to happen, at least the system would (hopefully) keep my ppO2 up. I would rely on buddies, but I find doing predive checks on them doesn't always give the desired result

The main benefit that I see is that I can fly pure eCCR when the dive calls for it and to remove the depth restriction posed by the CMF orifice. With the rEvo controller this is a very simple change.

OceanOpportunity · 22nd April 2008, 11:58

Quote: (Originally Posted by PnL)

Is there any evidence to suggest that the solenoid would not fire in "parachute" mode when you need it? I've never had a solenoid on my rig so I'm curious to what the failure rate of eCCR's are such that this is a real concern during a dive, especially if you are doing your predives and the solenoid is firing properly.

The main benefit that I see is that I can fly pure eCCR when the dive calls for it and to remove the depth restriction posed by the CMF orifice. With the rEvo controller this is a very simple change.

I've had a solenoid freeze up...in fact, the whole computer froze up. My point is that electronics are what they are, and they can fail, so why depend on them as a backup if you arent absolutely sure that its going to work (hearing it fire regularly). Another analagous situation, like a continuously blinking HUD I mentioned earlier in the thread, would eb a recent discussion in the homebuilders forum where folks wnated to ensure that the digital readout for a cell went to 2 decimal places. If you see the last digit flick around a bit, that's a good thing, since you know the electronics are responsive, and that the cells aren't flaky.

Again, I do like the idea of being able to quickly convert my unit between modes (e/m CCR) depending on the mission requirements.

With regard to the incident referenced by mik. A solenoid may have eliminated the incident altogether, yes. However there were a number of issues leading to the problem which IMO could have been avoided by having more control and taking more responsibility over the dive. More fail-safe (in theory) equipment is no substitute for proper training and planning. Note that regardless of the rig I'm diving...I'm using 100% O2 to 20feet for a number of reasons...one of those things I was never taught in a class but came to light after gaining a better appreciation of what exactly is going on with a CCR.

I could be wrong, but I'm still of the less is more philosophy. I want even more control over my rig, so less gizmos...Guess I'm not a candidate for the Cis Mk6!

21st April 2008, 03:13	#11 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 517	Re: Hybrid Rebreathers I'm still on the fence about the logic behind using a hybrid O2 injection method. Having been originally trained on a variety of eCCR's, and having switched to mCCR (largely in an effort to simplify my rig and reduce failure points), I still look at this as unnecessarily complex...I am open to being swayed otherwise. When diving, or even using, anything that is electronic/computer controlled the system earns our confidence by our recognizing that it is functioning properly at easily measured and recognized intervals. For example, in some recent discussion on HUDs, most agreed that at least one LED should blink continuously, rather than stay lit as we know that the HUD is responsive to the cells. In the case of an eCCR, during a dive, much of my confidence in an eCCR system is by hearing the solenoid firing on regular intervals. After a while, it's like clockwork. You should be checking your handsets regularly anyway, but in the event that you arent hearing a solenoid firing, its a safe bet to assume that it isnt working, and you need another means to get O2 in to the unit. On all eCCRs, solenoid is our primary means of injecting O2, a manual add button is the backup. Now, on mCCR, we rely on the orifice with routine/consistent manual injections. This is a similar pattern of recognition, just like hearing the solenoid fire, that ensures things are working properly. Orifice fails somehow and we are still injecting manually, just more regularly, to maintain a desired setpoint. Having said this, and pointing out 'patterns of recognition' in both methods, I feel like a hybrid O2 injection method, depending on how its dived, takes away the need for an individual to recognize these patterns, and gain confidence in the system. Assume we dive mCCR as our primary, with a solenoid backing us up. The solenoid would never fire, unless we weren't doing our job with manual injections at all. Even at that, the O2 decay time to get there would be quite lengthy. Given that the solenoid hasn't been regularly firing the whole dive, I'm not convinced that I would then depend on it in a pinch, and even at that, why bother if your manually adding anyway? Conversely, if we dive eCCR/solenoid as primary with an orifice as secondary, all that is happening is prolonging automatic injections. Why bother? I'd rather know that my solenoid is firing, and with a recognizable frequency. I made the switch to mCCR to simplify things after having a few troubles with various electronics/solenoids. I do the same dives, and feel like I've become a better CCR diver since mCCR forces those patterns to become part of my dive, hence I've earned a better appreciation for what is going on in my loop. If, and thats a big IF, I saw the utility value in a hybrid approach, it would be for very extended range diving, with both systems completely isolated from one another. In this case, I would dive eCCR/solenoid mode until it failed, at which point I would flip a valve and allow my orifice to trickle. This simply assists in what could be a laborious tasks of manually adding to come back home when very far away. Using both methods together, IMO, unnecessarily complicates what should be a very simple and recognizeable mode of diving. Definitely interested in being taken to task on my way of thinking here... __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream Last edited by OceanOpportunity : 21st April 2008 at 03:18.
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21st April 2008, 04:12	#12 (permalink)
PnL Custom Title Allowed! Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Mar 2007 Location: San Diego, CA Posts: 177	Re: Hybrid Rebreathers Hi Mike, For me, the benefit of having a hybrid system is the ability to set my rig to the type of diving that I will be doing. For general diving, and perhaps for dives where I may be more task loaded then usual, I would dive my rig in mCCR mode with the controller as a silent backup system. For a dive where I know that I will be task loaded (e.g., video), I can dive the rig in full eCCR mode. This also removes the depth limitations that a CMF orifice places on an mCCR unit and is one way of getting deeper without much fiddling on the rig. This is the main reason I think a hybrid system is nice. I dive a fully mCCR rig (rEvo) right now and like the fact that its a mCCR and "simple", as you state. But having the option to easily covert to a parachute system (hybrid), or full eCCR can have its advantages depending on the dive. This is, of course, MHO. Regards, Paul __________________ SDTechDiving.com - A San Diego Technical Diving Community
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21st April 2008, 06:11	#13 (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: Hybrid Rebreathers Quote: (Originally Posted by dave t) slightly off thread but my belief is that the reason why MCCr's have a good safety record is the "mindset" they instill in the diver. Adding auto functions may deteriorate that mindset! Dave That is my concern, though I doubt that comes as a surprise . Given the choice between manual injection and auto... I'd go with auto... so I don't give myself the choice. I also found Michael's post very well spoken... greened. the hybrid approach is an interesting idea though. It may prove a step forward for eCCR's but not sure about the reverse. Also curious about hybrid needle valve eCCR's... anyone trying that? One thing is almost irrefutable, having the manual option on remote trips will be very convenient in the case of a melt down in the injection system... that would surely boost reliability for eCCR's. Verifying that both systems work in pre-dive mode would be key. A flow meter for the orifice and A dilluent flush for the solenoid aught to do it. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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21st April 2008, 06:21	#14 (permalink)
Stephane Hey! Ho! Let's go! Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 734	Re: Hybrid Rebreathers Hello Gill, Quote: Verifying that both systems work in pre-dive mode would be key. A flow meter for the orifice and A dilluent flush for the solenoid aught to do it. A flow meter before each dive? No need! Just verify that there is a flow of gas. Diluent flush for the solenoid? It delivers O2 ... __________________ Stéphane Hammer-rEvo powered!
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21st April 2008, 07:44	#15 (permalink)
J. V. Custom Title Allowed! Current Rebreather/s: rEvo Other Rebreather/s: Not Bought Yet rEvo Join Date: Mar 2006 Location: Lot & Savoie Posts: 233	Re: Hybrid Rebreathers Why I use an hybrid rEvo Cause with an hybrid I do just what I want to do. - I want a mCCR cause the dive profil is yoyo or to preserve solenoïd battery? I put the set point on 0.5 - I need my two hands to install a line or something like that? I put the set point on 1.2 or more. - I want to dive deeper than the fixed IP limit? I just take off a bolt and put on an other. - My beautiful electronic is out and need to go back to the manufacturer? I continue to dive in mCCR. - The O2 orifice is clogged? I continue to dive in eCCR mode. Etc. In fact, I've not a rebreather, I've two rebreather. __________________ -------------------- Jacques NPSFQQA-EDS IT # 007 (remué non agité)
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21st April 2008, 08:05	#16 (permalink)
Ben Field CK+Shearwater Current Rebreather/s: Classic Kiss Other Rebreather/s: Sport Kiss Join Date: Aug 2005 Location: London, England Posts: 1,554	Re: Hybrid Rebreathers I'm currently of the opinion that Hybrids in come form represent the future for recreational units- if a balance can be found to force people into the MCCR paranoid operation mode and not relying on the electronics- so its there as just a parachute to boost PPO2 when you've really missed something (somewhere below 0.5?) A couple of elements are IMO stumbling blocks- 1. First stage- MCCR's require (generally) high but fixed IP, whereas Solenoids require low but balanced IP. Recreational units would be overcomplicated with twin O2 tanks, even H valves and two regs- I think that a Dual IP output reg or similar system is required before this is viable for the majority. 2. Battery Life. On MCCR's we are used to massive battery life 6-12months, on ECCR the battery life is pitiful due to the Solenoid, 20-40hours top I believe> (1 dive if you have certain units!) With a Hybrid where the MCCR operation is effectively extending the Solenoid batteries life how do you predict/guard against it failing? I could dive 4months on almost purely MCCR apart from testing the solenoid then when an emergancy happens (CBL a buddy for example) and I rely on the Parachute/solenoid side of my system, only to find the 4month old battery can't run the ECCR part sufficently... Maybe the ECCR should be wind up? __________________ www.hugsac.org.uk Beware Fridge Suck
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22nd April 2008, 01:31	#17 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 517	Re: Hybrid Rebreathers This perspective I can greatly appreciate, and it makes alot of sense: Quote: (Originally Posted by J. V.) In fact, I've not a rebreather, I've two rebreather. The ability to switch one platform between O2 injection modes does solve alot by way of mission specific considerations. Then of course, we EITHER dive mCCR OR eCCR. I'm still not buying any logic on utilizing both methods synergistically. I will admit that I went through a mindset just over a year ago, when I first switched to mCCR, that I wanted to see a 'parachute' in effect. The more I've considered what this would do for me, the less I like the idea. Again, when using electronics, not simply as a monitoring device, but as a controller of a specific mechanism, I am going to look for some recognizeable pattern such that I know it is functioning properly. When used as a parachute, waiting an hour or more into the dive for the thing to fire does not instill any additional confidence or assurance. IMO, it does the opposite...I'd be so paranoid that the thing wouldnt work when needed that I'd be paying EXTRA close attention to my monitoring devices and manual injections...I'd never need the parachute. As they say, there's two ways to skin a cat is there any evidence based logic to support the benefits of a hybrid system (both modes synergistically)..any personal experiences where this wouldve been beneficial? As a point of clarification...I think that by offering the two modes as an option for a unit is a brilliant move by the mfg's. It does give the end user two rigs for the price of one (+/-). I jsut dont buy utilization of both modes at the same time. __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
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22nd April 2008, 03:08	#18 (permalink)
mik New Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Sep 2006 Location: Sydney North Posts: 63	Re: Hybrid Rebreathers Quote: (Originally Posted by OceanOpportunity) is there any evidence based logic to support the benefits of a hybrid system (both modes synergistically)..any personal experiences where this wouldve been beneficial? As a point of clarification...I think that by offering the two modes as an option for a unit is a brilliant move by the mfg's. It does give the end user two rigs for the price of one (+/-). I jsut dont buy utilization of both modes at the same time. How about this incident? __________________ It just fell apart in my hands, Chief!
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22nd April 2008, 04:07	#19 (permalink)
PnL Custom Title Allowed! Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Mar 2007 Location: San Diego, CA Posts: 177	Re: Hybrid Rebreathers Quote: (Originally Posted by OceanOpportunity) When used as a parachute, waiting an hour or more into the dive for the thing to fire does not instill any additional confidence or assurance. IMO, it does the opposite...I'd be so paranoid that the thing wouldnt work when needed that I'd be paying EXTRA close attention to my monitoring devices and manual injections...I'd never need the parachute. Mike, Is there any evidence to suggest that the solenoid would not fire in "parachute" mode when you need it? I've never had a solenoid on my rig so I'm curious to what the failure rate of eCCR's are such that this is a real concern during a dive, especially if you are doing your predives and the solenoid is firing properly. For me, the "parachute" system is purely backup - I am still the one responsible for maintaining my ppO2 and I always will be when flying manual, I don't think there are two ways about it. But if I were to pass out, or something else were to happen, at least the system would (hopefully) keep my ppO2 up. I would rely on buddies, but I find doing predive checks on them doesn't always give the desired result The main benefit that I see is that I can fly pure eCCR when the dive calls for it and to remove the depth restriction posed by the CMF orifice. With the rEvo controller this is a very simple change. __________________ SDTechDiving.com - A San Diego Technical Diving Community
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22nd April 2008, 11:58	#20 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 517	Re: Hybrid Rebreathers Quote: (Originally Posted by PnL) Is there any evidence to suggest that the solenoid would not fire in "parachute" mode when you need it? I've never had a solenoid on my rig so I'm curious to what the failure rate of eCCR's are such that this is a real concern during a dive, especially if you are doing your predives and the solenoid is firing properly. The main benefit that I see is that I can fly pure eCCR when the dive calls for it and to remove the depth restriction posed by the CMF orifice. With the rEvo controller this is a very simple change. I've had a solenoid freeze up...in fact, the whole computer froze up. My point is that electronics are what they are, and they can fail, so why depend on them as a backup if you arent absolutely sure that its going to work (hearing it fire regularly). Another analagous situation, like a continuously blinking HUD I mentioned earlier in the thread, would eb a recent discussion in the homebuilders forum where folks wnated to ensure that the digital readout for a cell went to 2 decimal places. If you see the last digit flick around a bit, that's a good thing, since you know the electronics are responsive, and that the cells aren't flaky. Again, I do like the idea of being able to quickly convert my unit between modes (e/m CCR) depending on the mission requirements. With regard to the incident referenced by mik. A solenoid may have eliminated the incident altogether, yes. However there were a number of issues leading to the problem which IMO could have been avoided by having more control and taking more responsibility over the dive. More fail-safe (in theory) equipment is no substitute for proper training and planning. Note that regardless of the rig I'm diving...I'm using 100% O2 to 20feet for a number of reasons...one of those things I was never taught in a class but came to light after gaining a better appreciation of what exactly is going on with a CCR. I could be wrong, but I'm still of the less is more philosophy. I want even more control over my rig, so less gizmos...Guess I'm not a candidate for the Cis Mk6! __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream Last edited by OceanOpportunity : 22nd April 2008 at 12:02.
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