Deep air on OC vs. CCR

robvdmr13 · 9th January 2007, 13:12

Quote: (Originally Posted by Doppler)

I would like to ask this crowd (given the pn2 being equal) have any of you found the difference in thermal stress between OC and CC has a descernable effect on your perception of narcosis?

Thanks

No, not really. Even in cold waters I don`t really notice/think the thermal benefit of a CCR is lessening my narcosis. But that may also be caused by the higher helium concentration I usually use on CCR.

Robert

tecdivertraining · 9th January 2007, 13:12

Quote: (Originally Posted by heigo)

80m oc
60m ccr

Mainly because i cant get any helium.

pete please tell me your not doing that in similan!!!!!!

Abbo · 9th January 2007, 14:25

Quote: (Originally Posted by heigo)

80m oc
60m ccr

80m on air is PO2=1.89
You've got brass balls mate!
PO2 CNS%/minute
1.4 0.65%
1.5 0.83%
1.6 2.22%
1.7 10%
1.8 50%
1.82 100%

PoulO · 9th January 2007, 14:28

1. OC 55 meter
2. CCR 40 meter

I will normaly use air diluent at dives until 30 meter and trimix below that even if helium is available. My dive computer also gives less deco on air then trimix.

Regards
Poul

Mark Chase · 9th January 2007, 15:47

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

40-50m is ok in the red sea simple OW reef dive. Probably 40max for anything tricky. I did go to 65 once in little Canyon but that was a momnet of madness. Cracking dive thow.

ATB

Mark Chase

Gadget · 9th January 2007, 16:33

everything is reletive we are all different i used to regually dive to 200ft + on air whilst on OC these days i dont bother putting helium in the unit till i am going below 150ft and this is in uk waters. this work for me not saying it is going to work for everyone.

teksimple · 9th January 2007, 16:50

I am sure I would get flamed if I posted how deep I have gone using air diluent (and before that with OC), so I won't. I do not do THAT stupid crap any more since I took my trimix courses. I have got plenty of OTHER stupid crap to get me in trouble as it is.

One thing I haven't seen mentioned in this thread is that with the typical CCR conservative setpoint, diving real deep on air diluent not only increases narcosis, but it increases your nitrogen absorption with regard to decompression beyond what you would have on open circuit air. The only way around the increased narcosis and deco time is to jack up your set point to somewhere near the OC equivalent. The trade off is that your loop is starting to have all kinds of (nowadays) unhealthy characteristics.

Hell, if you were a US Navy diver in the Swede Momsen days, you were OK as long as your PO2 did not exceed 2.5!

6Gill · 9th January 2007, 23:44

Quote: (Originally Posted by robvdmr13)

No, not really. Even in cold waters I don`t really notice/think the thermal benefit of a CCR is lessening my narcosis. But that may also be caused by the higher helium concentration I usually use on CCR.

Robert

I have found thermal stress to enhance the effects of narcosis, along with low vis, fatigue, and hangovers.

Mixaddict · 9th January 2007, 23:47

For those of you who are uncomfortable posting depths on this thread, how about a simpler question:

1. Do you tend to feel the effects of narcosis at more shallow depths than you typically would on OC?

Regards,
Randy

RonMicjan · 10th January 2007, 04:11

Quote: (Originally Posted by Mixaddict)

For those of you who are uncomfortable posting depths on this thread, how about a simpler question:

1. Do you tend to feel the effects of narcosis at more shallow depths than you typically would on OC?

Regards,
Randy

not even close, there is not nearly the PPn2 in the loop until you get to the "matching" depth, do the math and see what the PPn2 is at various depths at a constant setpoint.

Any one who tells you that oxygen is as narcotic as nitrogen has never dived a CCR, try this experiment, take your unit to depth with a low setpoint, say 130fsw and a sp of .4, (you will have to sit and breathe it down a while) think about your narcotic level, estimate the level of "fog", "rapture" "stupidity" or whatever version of narcosis you personally feel. Then, bump the PO2 up to 1.4 or so and watch the fog roll away, like your sittin on the dock o' the bay. Of course, dont be hangin around at 130 on a .4 too long, and make sure you are tracking deco with a dive computer set to whatever you are breathing.

next experiement, do the same drill and after the loop is resting at .4, then flush the loop with 20/50 and REALLY see the fog roll away. air for dil? NOT!

out of curiosity, why the twenty questions on narcosis?

BTW, I have done air OC to 276, had an awesome encounter with an electric ray (at least I think I did

) back when I was young and stupid. Now air OC is limited to OW instruction depths and shallow salvage and body recovery dives. The vast majority of diving is done CCR on 20/30 to about 150ish and 10/50 deeper. I like to keep an END of around 100fsw or PN2 of 3.2 ish.

HELIUM is your FRIEND!

9th January 2007, 13:12	#21 (permalink)
robvdmr13 New Member Current Rebreather/s: Inspiration Classic Dolphin Other Rebreather/s: Dolphin Join Date: Jan 2006 Location: The Netherlands Posts: 44	Re: Deep air on OC vs. CCR Quote: (Originally Posted by Doppler) I would like to ask this crowd (given the pn2 being equal) have any of you found the difference in thermal stress between OC and CC has a descernable effect on your perception of narcosis? Thanks No, not really. Even in cold waters I don`t really notice/think the thermal benefit of a CCR is lessening my narcosis. But that may also be caused by the higher helium concentration I usually use on CCR. Robert
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9th January 2007, 13:12	#22 (permalink)
tecdivertraining EXPLORER Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon Ouroboros Dolphin Other Rebreather/s: Not Bought Yet Dolphin Join Date: May 2005 Location: Phuket, Thailand Posts: 531	Re: Deep air on OC vs. CCR Quote: (Originally Posted by heigo) 80m oc 60m ccr Mainly because i cant get any helium. pete please tell me your not doing that in similan!!!!!! __________________ Mathew Partridge Technical Director Pro-Tech Dive College www.protechdivers.com www.tech-ccr.com
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9th January 2007, 14:25	#23 (permalink)
Abbo Nicholas Smith Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 460	Re: Deep air on OC vs. CCR Quote: (Originally Posted by heigo) 80m oc 60m ccr 80m on air is PO2=1.89 You've got brass balls mate! PO2 CNS%/minute 1.4 0.65% 1.5 0.83% 1.6 2.22% 1.7 10% 1.8 50% 1.82 100% Last edited by Abbo : 9th January 2007 at 14:28.
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9th January 2007, 14:28	#24 (permalink)
PoulO New Member Current Rebreather/s: Evolution Other Rebreather/s: Megalodon Join Date: Dec 2005 Location: Copenhagen Denmark Posts: 25	Re: Deep air on OC vs. CCR 1. OC 55 meter 2. CCR 40 meter I will normaly use air diluent at dives until 30 meter and trimix below that even if helium is available. My dive computer also gives less deco on air then trimix. Regards Poul Last edited by PoulO : 9th January 2007 at 14:30.
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9th January 2007, 15:47	#25 (permalink)
Mark Chase RBW Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,858	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 40-50m is ok in the red sea simple OW reef dive. Probably 40max for anything tricky. I did go to 65 once in little Canyon but that was a momnet of madness. Cracking dive thow. ATB Mark Chase __________________ See my "Doing It Chasey" video where I'm locked into a padded room, naked, with two ball bearings and within an Hour, I manage to lose one and break the other!!! Kevin Juergensen 16/11/08 [/quote]
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9th January 2007, 16:33	#26 (permalink)
Gadget Custom Title Allowed! Current Rebreather/s: Megalodon rEvo Dolphin Home Build Other Rebreather/s: rEvo Dolphin Home Build Join Date: May 2005 Location: Hoddesdon, Herts. Posts: 163	Re: Deep air on OC vs. CCR everything is reletive we are all different i used to regually dive to 200ft + on air whilst on OC these days i dont bother putting helium in the unit till i am going below 150ft and this is in uk waters. this work for me not saying it is going to work for everyone. __________________ Si Lawrence www.divehdi.com
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9th January 2007, 16:50	#27 (permalink)
teksimple RBW Member Current Rebreather/s: MK 15.X Other Rebreather/s: Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Haifa Street, Baghdad Posts: 514	Re: Deep air on OC vs. CCR I am sure I would get flamed if I posted how deep I have gone using air diluent (and before that with OC), so I won't. I do not do THAT stupid crap any more since I took my trimix courses. I have got plenty of OTHER stupid crap to get me in trouble as it is. One thing I haven't seen mentioned in this thread is that with the typical CCR conservative setpoint, diving real deep on air diluent not only increases narcosis, but it increases your nitrogen absorption with regard to decompression beyond what you would have on open circuit air. The only way around the increased narcosis and deco time is to jack up your set point to somewhere near the OC equivalent. The trade off is that your loop is starting to have all kinds of (nowadays) unhealthy characteristics. Hell, if you were a US Navy diver in the Swede Momsen days, you were OK as long as your PO2 did not exceed 2.5!
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9th January 2007, 23:44	#28 (permalink)
6Gill Custom Title Allowed! Current Rebreather/s: Megalodon Classic Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Washington state Posts: 112	Re: Deep air on OC vs. CCR Quote: (Originally Posted by robvdmr13) No, not really. Even in cold waters I don`t really notice/think the thermal benefit of a CCR is lessening my narcosis. But that may also be caused by the higher helium concentration I usually use on CCR. Robert I have found thermal stress to enhance the effects of narcosis, along with low vis, fatigue, and hangovers. __________________ "It's a shame ignorance isn't painful!"
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9th January 2007, 23:47	#29 (permalink)
Mixaddict RBW Member Current Rebreather/s: Inspiration Vision Evolution Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Jan 2006 Location: Draper, Utah USA Posts: 520	Re: Deep air on OC vs. CCR For those of you who are uncomfortable posting depths on this thread, how about a simpler question: 1. Do you tend to feel the effects of narcosis at more shallow depths than you typically would on OC? Regards, Randy __________________ Randy Thornton (MixAddict) Inspiration, Evolution, Hammerhead & Sentinel CCR Instructor
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10th January 2007, 04:11	#30 (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: 1,120	Re: Deep air on OC vs. CCR Quote: (Originally Posted by Mixaddict) For those of you who are uncomfortable posting depths on this thread, how about a simpler question: 1. Do you tend to feel the effects of narcosis at more shallow depths than you typically would on OC? Regards, Randy not even close, there is not nearly the PPn2 in the loop until you get to the "matching" depth, do the math and see what the PPn2 is at various depths at a constant setpoint. Any one who tells you that oxygen is as narcotic as nitrogen has never dived a CCR, try this experiment, take your unit to depth with a low setpoint, say 130fsw and a sp of .4, (you will have to sit and breathe it down a while) think about your narcotic level, estimate the level of "fog", "rapture" "stupidity" or whatever version of narcosis you personally feel. Then, bump the PO2 up to 1.4 or so and watch the fog roll away, like your sittin on the dock o' the bay. Of course, dont be hangin around at 130 on a .4 too long, and make sure you are tracking deco with a dive computer set to whatever you are breathing. next experiement, do the same drill and after the loop is resting at .4, then flush the loop with 20/50 and REALLY see the fog roll away. air for dil? NOT! out of curiosity, why the twenty questions on narcosis? BTW, I have done air OC to 276, had an awesome encounter with an electric ray (at least I think I did ) back when I was young and stupid. Now air OC is limited to OW instruction depths and shallow salvage and body recovery dives. The vast majority of diving is done CCR on 20/30 to about 150ish and 10/50 deeper. I like to keep an END of around 100fsw or PN2 of 3.2 ish. HELIUM is your FRIEND! __________________ Marine rescue, towing and salvage. Interfering with natural selection since 1983. www.tmishop.com Diving bits etc. www.seatowpdx.com The Summer Job Last edited by RonMicjan : 10th January 2007 at 04:23.
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