Deep air on OC vs. CCR

Mixaddict · 8th January 2007, 22:50

OK, before everyone starts screaming "Don't do it!", please give me your thoughts on the comparison between the two. In other words, I am interested in whether you feel that the narcosis level is more severe on CCR vs. OC. Also, I am curious at what depth you personally feel that the narcosis level becomes too severe on CCR.

Just so we are all on the same page, let's pretend we are all diving in warm, clear, still water. Work load will be moderate.

Please no lectures on the disadvantages of diving deep on air. I think that everyone on this board is aware of any issues with deep air. I am just interested at what depth level it becomes unmanageable for you on CCR and how that compares to your OC experience.

Thanks in advance,
Randy

Russ · 8th January 2007, 23:16

Sadly I wish I could use the warm clear water experience instead of the dark, 39 degree F, still learning on the CCR but my limit is around 140 ft while on OC it was around 150ft. I guess thats not deep air diving but thats what He is for

In general I feel I need to be more clear headed on ccr as there are more options in case of failure compared to simply turning valves on OC.

Russ

Mike · 8th January 2007, 23:31

Either way, I think you need to be having a good long think about diving air around the 50m mark. Both Narcosis and PPO2 start becoming issues as you go much past there.

In practice, I pretty much always dive air on OC, and almost never use air dil on CCR.

Mike

chunter · 8th January 2007, 23:47

For me, the narcosis is comparable on OC vs. CCR, however, the "task loading" factor comes into play much sooner on CCR. On OC, if you are breathing, you are probably ok, but that isn't the case on CCR. I find that the loss of time perception plays a big part in the danger of being narked on a CCR because it is difficult to tell how long it has been since I checked my PPO2, and in the event it has drifted below setpoint, how long was it below for? I used to do deep air dives to 200 feet regularly on OC, but I try not to push CCR air past 160 ft.

The real question is, if you are diving deep on CCR, why wouldn't you use trimix? Can't get helium? Can't afford the 2 cubic feet of gas?

Aloha,
Charlie

Dave & Sandy · 9th January 2007, 00:16

We would dive air to 60m on OC mainly due to the cost. All of our local weekend diving is in the region of 45m-60m so you'd be going through the He quickly on OC.

We wish to avoid/reduce narcosis as much as possible diving Rebreather so can't compare the effects of narcosis between OC and RB

Since switching to Rebreather we dive a mix on every dive. He cost is insignificant when adding He to your 3L dil and you get several dives from a full dil. We feel a clear head is important to sort out even a small problem and be able to monitor PO2 on a regular basis. I'd say anything past 30m on a RB, for the almost non existent effort to mix up yourself and very low cost, why not use a He mix.

Just our opinion however, others do things differently.

Mixaddict · 9th January 2007, 04:40

I guess I should have qualified my question with stating:

1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?"

2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?"

Thanks for your input.

Regards,
Randy

RonMicjan · 9th January 2007, 04:55

Quote: (Originally Posted by Mixaddict)

I guess I should have qualified my question with stating:

1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?"

2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?"

Thanks for your input.

Regards,
Randy

doing the math...at 155 fsw on a ccr at 1.2 PO2, you are diving air, with the same level of narcosis, anything deeper than that at 1.2, you are getting MORE narced on the CCR than you would on air, if you bump the PO2 setpoint up to 1.3, then you are equilivant to air at 172fsw. you can also bump to 1.4 for your max depth to manage the narcosis.

pick the equilivant air depth you are comfortable with and chose setpoint and depth accordingly. anything below 100fsw END for me and I add helium to maintain that END. If no helium, I would not usually go below the 150ish range.

jhaaja · 9th January 2007, 04:55

Quote: (Originally Posted by Mixaddict)

I guess I should have qualified my question with stating:

1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?"

2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?"

Thanks for your input.

Regards,
Randy

1) On OC 40m, ~120ft
2) On CC 30m, ~90ft

6Gill · 9th January 2007, 06:03

Quote: (Originally Posted by Mixaddict)

I guess I should have qualified my question with stating:

1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?"

2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?"

Thanks for your input.

Regards,
Randy

OC - 160
CCR - 140

mortenkjerulff · 9th January 2007, 06:35

Quote: (Originally Posted by Mixaddict)

OK, before everyone starts screaming "Don't do it!", please give me your thoughts on the comparison between the two. In other words, I am interested in whether you feel that the narcosis level is more severe on CCR vs. OC. Also, I am curious at what depth you personally feel that the narcosis level becomes too severe on CCR.

Just so we are all on the same page, let's pretend we are all diving in warm, clear, still water. Work load will be moderate.

Please no lectures on the disadvantages of diving deep on air. I think that everyone on this board is aware of any issues with deep air. I am just interested at what depth level it becomes unmanageable for you on CCR and how that compares to your OC experience.

Thanks in advance,
Randy

Hi.

I do not feel any difference, but I am concerned about the WOB on CC. If you get a CO2 build up, in my experience, the narcosis level quickly rises (and maybe to an unmanageable level!)

So as I see it, you can go equally deep, but CC may quickly bite you somewhere unpleasant

if you are in the extended range region or below.

Best regards
Morten

8th January 2007, 22:50	#1 (permalink)
Mixaddict Always Learning! Current Rebreather/s: Inspiration Vision Evolution Other CCR Dolphin Other Rebreather/s: Inspiration Classic Other CCR Dolphin Join Date: Jan 2006 Location: Draper, Utah USA Posts: 415	Deep air on OC vs. CCR OK, before everyone starts screaming "Don't do it!", please give me your thoughts on the comparison between the two. In other words, I am interested in whether you feel that the narcosis level is more severe on CCR vs. OC. Also, I am curious at what depth you personally feel that the narcosis level becomes too severe on CCR. Just so we are all on the same page, let's pretend we are all diving in warm, clear, still water. Work load will be moderate. Please no lectures on the disadvantages of diving deep on air. I think that everyone on this board is aware of any issues with deep air. I am just interested at what depth level it becomes unmanageable for you on CCR and how that compares to your OC experience. Thanks in advance, Randy __________________ Randy Thornton (MixAddict) Inspiration, Evolution,Hammerhead & Sentinel CCR Instructor
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8th January 2007, 23:16	#2 (permalink)
Russ New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jul 2006 Posts: 88	Re: Deep air on OC vs. CCR Sadly I wish I could use the warm clear water experience instead of the dark, 39 degree F, still learning on the CCR but my limit is around 140 ft while on OC it was around 150ft. I guess thats not deep air diving but thats what He is for In general I feel I need to be more clear headed on ccr as there are more options in case of failure compared to simply turning valves on OC. Russ
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8th January 2007, 23:31	#3 (permalink)
Mike Prism 'prentice Current Rebreather/s: Prism Topaz Other Rebreather/s: Inspiration Classic Evolution Join Date: Feb 2005 Location: Melbourne Posts: 318	Re: Deep air on OC vs. CCR Either way, I think you need to be having a good long think about diving air around the 50m mark. Both Narcosis and PPO2 start becoming issues as you go much past there. In practice, I pretty much always dive air on OC, and almost never use air dil on CCR. Mike __________________ Open ....... Closed Mind ........ Loop
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8th January 2007, 23:47	#4 (permalink)
chunter I like diving Current Rebreather/s: Sport Kiss MK 15.X Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Classic Kiss Join Date: Jul 2006 Location: Honolulu Posts: 455	Re: Deep air on OC vs. CCR For me, the narcosis is comparable on OC vs. CCR, however, the "task loading" factor comes into play much sooner on CCR. On OC, if you are breathing, you are probably ok, but that isn't the case on CCR. I find that the loss of time perception plays a big part in the danger of being narked on a CCR because it is difficult to tell how long it has been since I checked my PPO2, and in the event it has drifted below setpoint, how long was it below for? I used to do deep air dives to 200 feet regularly on OC, but I try not to push CCR air past 160 ft. The real question is, if you are diving deep on CCR, why wouldn't you use trimix? Can't get helium? Can't afford the 2 cubic feet of gas? Aloha, Charlie
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9th January 2007, 00:16	#5 (permalink)
Dave & Sandy New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2006 Location: Melbourne, Australia Posts: 92	Re: Deep air on OC vs. CCR We would dive air to 60m on OC mainly due to the cost. All of our local weekend diving is in the region of 45m-60m so you'd be going through the He quickly on OC. We wish to avoid/reduce narcosis as much as possible diving Rebreather so can't compare the effects of narcosis between OC and RB Since switching to Rebreather we dive a mix on every dive. He cost is insignificant when adding He to your 3L dil and you get several dives from a full dil. We feel a clear head is important to sort out even a small problem and be able to monitor PO2 on a regular basis. I'd say anything past 30m on a RB, for the almost non existent effort to mix up yourself and very low cost, why not use a He mix. Just our opinion however, others do things differently. __________________ Cheers, Dave & Sandy Atvar shows Dave & Sandy testing their new habitat 101 and home build RBMK69's Last edited by Dave & Sandy : 9th January 2007 at 00:58.
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9th January 2007, 04:40	#6 (permalink)
Mixaddict Always Learning! Current Rebreather/s: Inspiration Vision Evolution Other CCR Dolphin Other Rebreather/s: Inspiration Classic Other CCR Dolphin Join Date: Jan 2006 Location: Draper, Utah USA Posts: 415	Re: Deep air on OC vs. CCR I guess I should have qualified my question with stating: 1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?" 2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?" Thanks for your input. Regards, Randy __________________ Randy Thornton (MixAddict) Inspiration, Evolution,Hammerhead & Sentinel CCR Instructor
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9th January 2007, 04:55	#7 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,081	Re: Deep air on OC vs. CCR Quote: (Originally Posted by Mixaddict) I guess I should have qualified my question with stating: 1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?" 2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?" Thanks for your input. Regards, Randy doing the math...at 155 fsw on a ccr at 1.2 PO2, you are diving air, with the same level of narcosis, anything deeper than that at 1.2, you are getting MORE narced on the CCR than you would on air, if you bump the PO2 setpoint up to 1.3, then you are equilivant to air at 172fsw. you can also bump to 1.4 for your max depth to manage the narcosis. pick the equilivant air depth you are comfortable with and chose setpoint and depth accordingly. anything below 100fsw END for me and I add helium to maintain that END. If no helium, I would not usually go below the 150ish range. __________________ Ron "Life is pain princess, anyone who tells you different, is selling something", The Dread Pirate Wesley. www.tmishop.com Diving bits etc.
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9th January 2007, 04:55	#8 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 867	Re: Deep air on OC vs. CCR Quote: (Originally Posted by Mixaddict) I guess I should have qualified my question with stating: 1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?" 2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?" Thanks for your input. Regards, Randy 1) On OC 40m, ~120ft 2) On CC 30m, ~90ft
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9th January 2007, 06:03	#9 (permalink)
6Gill Custom Title Allowed! Current Rebreather/s: Megalodon Classic Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Washington state Posts: 115	Re: Deep air on OC vs. CCR Quote: (Originally Posted by Mixaddict) I guess I should have qualified my question with stating: 1. "How deep would you be willing to dive air on OC in warm, clear, still water, moderate work load when no helium is available?" 2. "How deep would you be willing to dive with air dil on CCR in warm, clear, still water, moderate work load when no helium is available?" Thanks for your input. Regards, Randy OC - 160 CCR - 140 __________________ "It's a shame ignorance isn't painful!"
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9th January 2007, 06:35	#10 (permalink)
mortenkjerulff Customise Me! Current Rebreather/s: Megalodon Other Rebreather/s: Not Bought Yet Join Date: Mar 2005 Location: Denmark Posts: 133	Re: Deep air on OC vs. CCR Quote: (Originally Posted by Mixaddict) OK, before everyone starts screaming "Don't do it!", please give me your thoughts on the comparison between the two. In other words, I am interested in whether you feel that the narcosis level is more severe on CCR vs. OC. Also, I am curious at what depth you personally feel that the narcosis level becomes too severe on CCR. Just so we are all on the same page, let's pretend we are all diving in warm, clear, still water. Work load will be moderate. Please no lectures on the disadvantages of diving deep on air. I think that everyone on this board is aware of any issues with deep air. I am just interested at what depth level it becomes unmanageable for you on CCR and how that compares to your OC experience. Thanks in advance, Randy Hi. I do not feel any difference, but I am concerned about the WOB on CC. If you get a CO2 build up, in my experience, the narcosis level quickly rises (and maybe to an unmanageable level!) So as I see it, you can go equally deep, but CC may quickly bite you somewhere unpleasant if you are in the extended range region or below. Best regards Morten
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