How much Deco

Moray Brown · 14th February 2008, 23:20

Confused

Surely anyone carrying 50% will know to be on it from 21m and not 6m...

Quote: (Originally Posted by Gobfish1)

No braging m8 ,
just saying what i see with the divers i dive with .. IANTD and all the other outfits
only tell the great unwashed to dive with a low set point to keep them away from 02 at 6m ,, and i will tell you why ( they cant hold a stop that,s it ,,)
all well and good, but we end up with divers that are worried shitless about having o2 with a ppo2 of 1.6 in the ccr , maybe that,s why you see lots of ccr divers passing out in 6m or less ,, LOW ppo2 kills as well , so best we all dive some place in the middle , but you need infomation to know were the middle is

even ap say 1,3 for air dives on a ybod ,,

OC and ppo2

as for diving OC the numbers started at 1.5ppo2, less .5 for diving in cold water less, .5 for a hard work .. and 1.6 for deco , we all know it is the best ppo2 to be on ,, for deco , keep you're eye on the cns clock , i can do that on the fly as i dive, its not hard ,,, well it could be hard if you only got a book to look them up in ,,, cos you were never told how to work out your cns per min .. yes we have computers to work out are CNS, but they cant look a head as you dive ,

i see 100s of divers swimming round in 30 40m with a ali 80 of 50% , same dive could be done with a half full 3L cylinder of o2,
its not the divers fault that,s how he was told to do it ,,

ppo2 of 50% at 6m= useless, for deco ,,, but hay all the word love's it ,,,
its v safe if you cant hold a stop ,,, good for the mass ,
good for selling nitrox card, but its crap for deco,, you need twice as much deco gas .. all needs humping around = more shite hanging of a diver, more drag, more work, more gas used ,, and that,s be4 we even get to do the deco,,

just my 2p
i will stick with my ppo2 numbers, thank you ,,
ccr 1.3 and 1.6 for deco .
OC 1.4 / 1.45 max ppo2 on bottom deco 1.6ppo2
with well over a thousand dives on said numbers , i dont see why a should change now

dive safe,

Gobfish1 · 15th February 2008, 00:08

Quote: (Originally Posted by Moray Brown)

Confused

Surely anyone carrying 50% will know to be on it from 21m and not 6m...

only when you run a 1,6 pp2 for deco , if you run with the 1.2 bollox you wont be sucking on you're 50% at 21m will you ...

you miss the window and spend the rest of your deco on a low ppo2 that ant much good for deco ,,

this thread has a depth limit of 45 to 50m so one deco cylinder .. Yes
and most of the deco is at 6m, Yes

Moray Brown · 15th February 2008, 10:29

I take your point, but your statement is a bit broad.

Maybe they are MOD1 trained and are not experienced in raising set points for deco?
If you are relating to O/C divers, maybe they only have a 50% ticket.

If you relate of OC and CCR Trimix divers - who knows why they do it, but they do and if works for them then fair play.

Quote: (Originally Posted by Gobfish1)

only when you run a 1,6 pp2 for deco , if you run with the 1.2 bollox you wont be sucking on you 50% at 21m will you ...

you miss the window and spend the rest of your deco on a low ppo2 that ant much good for deco ,,

this thread has a depth limit of 45 to 50m so one deco cylinder .. Yes
and most of the deco is at 6m, Yes

Gobfish1 · 15th February 2008, 16:52

MOD1 trained and are not experienced in raising set points for deco?
big green button , simple i would think ,,,

O/C divers, maybe they only have a 50% tick
,, yes ,, but should that stop then from thinking,

my last post on this , im board with it ,,

tekdiver170 · 16th February 2008, 01:20

Quote: (Originally Posted by Gobfish1)

think you will find you're only talking for divers over the pond ..
all the divers i know run with 1,45 max bottom OC and 1,6 deco

CCR run 1.3 or 1.4 and 1.5 1.6 deco on dives in less that 50m

all this crap about low ppo2 is just for the unwashed ,,
i have been diving nitrox and mix gas for 15 years ,,

never had a problem with my ppo2 s or my deco ..
IANTD used to teach the facts , but have had to throw in some bull shit to sell it's nitrox and mix bollox to the mass ,, just cos you were told by some guy it's so ,
dont make it fact ,,,

as for deco tables i have about 8 of them on my computer
plus a shit load.s of books with tables in

take your pick they all give you a dif frigging number for a said dive ,,,

i said play with the numbers for fun not to dive on in the other post ,,
and i said you will get longer bottom time , like to see you do 60min at 50m on a set of 12L twins
i never said a word about how much deco would be needed

the art of diving mixgas seems to get's more diluted as the years pass bye ;;;
knobs teaching knobs teaching knobs = BS Send three and four pence, we're going to a dance.

It's good you have found a decompresssion plan that works for you, but you also have to take everything with a grain of salt before pushing that plan on everyone. The so called "Safe" PO2's were put in place base upon the % of people who were experiencing O2 tox symptoms in a chamber. One person may be a freak of nature and be perfectly fine to dive a 1.6PO2 for an entire 3 hour dive, others may start experiencing tox syptoms far sooner.

Through experience I know what my limitations are. At a PO2 of 1.6 I start experiencing tox symptoms at 12-14 min. Scary $hit when you start convulsing at 20' while breathing O2 for 12min. After all someone said I should be safe until the 15 min. gas break. Not being the brightest in the bunch I still thought I should be safe at a 1.6 for 15 min, so lets try it again. Sure enough next dive same results. My CNS clock was not filled in fact it was only at around 50%. Through trial and error this happened 3 more times. Then I got smart and moved to CCR. Now I can run "cooler" breathing mixtures and still make it to the surface with the divers on OC. Now I run a 1.1-1.2 on the bottom and deco with 1.25-1.3. Knock on wood no more O2 toxicity = happier Chris.

I would feel really bad if I gave someone the advice that said, in Europe O2 toxicity doesn't affect people the same way because we're on the other side of the ocean. Only to hear they later toxed while deco'ing at a PO2 of a 1.6.

As has been said over and over, decompression is an art not a science. You have to find what works best for you.

Gobfish1 · 16th February 2008, 03:22

Quote: (Originally Posted by tekdiver170)

It's good you have found a decompresssion plan that works for you, but you also have to take everything with a grain of salt before pushing that plan on everyone. The so called "Safe" PO2's were put in place base upon the % of people who were experiencing O2 tox symptoms in a chamber. One person may be a freak of nature and be perfectly fine to dive a 1.6PO2 for an entire 3 hour dive, others may start experiencing tox syptoms far sooner.

hold on there m8 ,i never said or posted, Some one should dive on a gas with a ppo2 of 1.6 for 3 hours ,
i said i deco out at 1.6 ppo2, but if your read my post, i do say, keep an eye on you're CNS .. i did not say what i run my CNS to ,, i did not say run you cns clock to over 400% as you would do if you swam round for 180mins sucking on a gas with a ppo2 of 1.6 .. fooking madnass after all,

i posted the ppo2s that i dive on ,, and have done forsome time ..
one guy says its not safe to run more than a 1.2 ppo2 and i say that s bollox i dive 1.3 or 1.4 , and 1.6 for deco, i have done over a thousand dives on said ppo2 s to back that info up ,,
i also said we should all pick a ppo2 some place in the middle and be safe ..

Through experience I know what my limitations are. At a PO2 of 1.6 I start experiencing tox symptoms at 12-14 min. Scary when you start convulsing at 20' while breathing O2 for 12min. After all someone said I should be safe until the 15 min. gas break. Not being the brightest in the bunch I still thought I should be safe at a 1.6 for 15 min, so lets try it again. Sure enough next dive same results. My CNS clock was not filled in fact it was only at around 50%. Through trial and error this happened 3 more times. Then I got smart and moved to CCR. Now I can run "cooler" breathing mixtures and still make it to the surface with the divers on OC. Now I run a 1.1-1.2 on the bottom and deco with 1.25-1.3. Knock on wood no more O2 toxicity = happier Chris.

experiencing tox symptoms now that's something you dont get to hear
Most just tox ,, if you feel you're in danger of having a tox when you CNS clock hit only 50% and you're ppo2 is up over 1.3 i would think you may need to talk with a diving Doc,,, it ant the norm ,, please if you have seen a DOC what did he say

I would feel really bad if I gave someone the advice that said, in Europe O2 toxicity doesn't affect people the same way because we're on the other side of the ocean. Only to hear they later toxed while deco'ing at a PO2 of a 1.6.

yes so would i
,, that's why i said keep you're eye on you're CNS clock
and we all know that you should not push it passed 80% says so in the book

if other diver run CNS s to well over 200% and are just fine , on matter ..

As has been said over and over, decompression is an art not a science. You have to find what works best for you.

my post were not about telling someone to dive on a said ppo2 or deco ...
i was posting to make a point , point was get all the infomation about mixgas diving , then make your choice ,, dont take it as fact just cos some guy says it s so on the internet ,, that go's for what in my post to , im v happy to see divers use what ever ppo2 they want , but im not happy when some one pops in and says diving a ppo2 above 1.2 is unsafe ,, remember this post was about a chap wanting to dive ccr in about 50m with limited deco ,,
the next new bunch of trimix diver, will be on the boards soon telling us all its not safe to dive a ppo2 above .9...
until a few of them passout in 6m or less ,,

100.000 divers, doing just fine, if one guy has a hit on a ppo2 of 1.3+ are we all then fooked is that it ,,,

thousands of scuba diver on holiday in the reasea / meldives right now swimming round on a nitrox 36% in 30m of water ,,, are they all dancing the jig ,

convulsing at 20' while breathing O2 for 12min.

worrying shit m8
so whats you're run time,s on your dives end CNS tell me more,,
how do you manage you're dives ,,, do you use a full face mask ,
even a 120min dive at 1.2ppo2 will put you're cns count over you're 50% so what do you do ..
tell us about you're tox symptoms number of time you have had them ...
how long can you last on a ppo2 of 1,5 ( .83 much better than 2,2 )
can you run a full 80%/100% cns clock on 1.2/1.3 ppo2 ,
is it just the 1.6 you cant hack ..

ps
I see you're in Honolulu, so no need to worry about o2 hit chris ,
them big Tiger Shark,s will get you first ,,

interesting post by the way, best reply to date,

tekdiver170 · 17th February 2008, 03:02

I wasn't trying to say you were preaching the know-all-end-all. It's unfortunate we have people who will read something and assume it right (for them) no matter where the info comes from. Maybe it's because I live in lawsuit happy America. I mean when we have people fill out Liability Releases for dive classes out here we have them first sign a Liability Waiver saying they won't sue us for getting writers cramps or carpel tunnel.

Now tiger sharks, are those the fury ones? They're kind'a cuddly.

A little about my tox experiences.

All of my O2 tox issues have happened on OC to date (knock on wood). They occurred on a variety of different dive profiles. The first being a dive to :30min dive to 150 on 25%, then 50% at 70' and 100% at 20'. I don't remember the exact profile we used for deco something around 6min at 70' 4min at 60' 1min at 50 1min at 40 3min at 30' and then switch to O2 @ 20' for 12min with a 3min planned ascent. O2 symptoms for all cases were the same. Diaphragm contractions/convulsions. Best way to describe it, you have no control over your breather pattern, your body just does what it wants and it's usually small short breaths. Immediate response was to switch to lowest PO2 (backgas) and try not to aspirate water.

Over the next year or so it happened another 4 times, most of them on a little bit deeper profile. Something like 200' on 18/45 for 25min. Switch to 35/25 at 120' for 2min every 10' until 70' switch to 50% for 8min at 70' 6min at 60' 2 min at 50 2min at 40 and 3 min. gas break at 30' and O2 at 20' for 15min and a 5 min ascent (Ascent=gas break). (Tox symp started on 100% at 20' 12-14 min.)

The worst case was a dive to 230' for :25 on 16/45. Switch to 35/25 at 120 3min every 10' until 80' 3min. gas break on backgas. At 70' 50% for 12min. 60' for 6min 50' for 3min 40' for 3 min 6min Gas break at 30'. By this time I started to believe in taking earlier gas breaks to the plan called for 10min on and 5 mins off O2 at 20' for 25min with a 5 min ascent.

I never made it to the 20' stop able to use this idea. I experienced the most severe contractions to this day 5 min into my 60' stop. Switched to backgas until 40' stop then back to 50%. Gas break at 30', then tried to go back on 02 at 20' only to have symptoms again after 4 1/2 min. I then did the rest of my deco doing 3min on and 3 min off O2, extending my deco time at 20 by 10min.

After this dive I did not do another deco dive until I got comfortable on my Rebreather. As I said knock on wood I have not had issues since, but I am super paranoid about it happening again and practice, practice, practice bailout techniques just in case.

There was a post by a guy last year who had the same type of O2 symptoms but he stayed on his loop a little too long and loss consciousness after less than a min of diaphragm convulsions. He was lucky and had a great buddy who was right there to assist. He lived. I tried to contact him for some further info but he declined to answer back.

tekdiver170 · 17th February 2008, 05:36

Quote: (Originally Posted by Gobfish1)

,,, do you use a full face mask ,
even a 120min dive at 1.2ppo2 will put you're cns count over you're 50% so what do you do ..
tell us about you're tox symptoms number of time you have had them ...
how long can you last on a ppo2 of 1,5 ( .83 much better than 2,2 )
can you run a full 80%/100% cns clock on 1.2/1.3 ppo2 ,
is it just the 1.6 you cant hack ..

I have not gone as far as a full face mask. On my Rebreather I have done dives in the 150 min. range at a 1.3 in shallower water < 100' and so far have not had an issue. But I have not yet pushed the limits at 1.3.

This leads me to believe 2 things. One is that my body just doesn't like PO2 at a 1.6, or maybe it's diving at deeper depths that leads to my issues at a higher PO2. Most of my deeper dives have bottom times in the 30 min. range. I dive with OC divers so this is what they're able to do with the tank sizes we dive out here in Hawaii.

It's funny even though I've done 150 min+ dives on my Rebreather in shallower water with a PO2 of a 1.3 but it's our deco dives I get more nervous about an O2 hit while on my deco at a 1.25 for only around an hour.

Abbo · 17th February 2008, 10:47

Gobfish,
I would assume that if we had results of tests on how many people ox toxed at what depth, we would see a bell curve. Right in the middle, at the peak occurance, would be the average PO2 at which people started break dancing. At that PO2, half the people would be safe and half would not. One standard deviation below that average, 84% of people would be safe. Two standard deviations below and 98% of people would be safe. What percentage of people would die using the PO2 you use? - because that percentage is never zero. The question is 'what fatality rate is acceptable?' Don't ask the diver: ask his wife. And don't ask me, as I wouldn't want those people on my conscience.

I would love to see those statistics, though, if anyone knows where to get them: what is the PO2 tolerance limit for the average person, what is one standard deviation, and is the relationship a normal distribution?

I don't know what my PO2 tolerance is -I've never had a hit - and I don't have much of a feeling for what the day-to-day variation is. I don't like taking risks where the effect is unknown. As I see it, with PO2s the benefits of taking those risks are negligible. But I'm sure you're right that I'm probably a very long way inside my tolerance limits.

***EBT*** · 17th February 2008, 11:04

Theres a cracking book, "oxygen and the diver" by kenneth donald..... he did research into O2 tolerance. Theres an excerpt of it HERE

The long and short of it is tolerance varies widely between individuals and even for the same individual over time. So we tend towards conservative limits, to reduce the % chance of a problem. Of course this means you can get away with higher limits, but with higher risk. Its a balancing act......

14th February 2008, 23:20	#21 (permalink)
Moray Brown CCR Training - MR Diving Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2006 Location: WMUK Posts: 261	Re: How much Deco Confused Surely anyone carrying 50% will know to be on it from 21m and not 6m... Quote: (Originally Posted by Gobfish1) No braging m8 , just saying what i see with the divers i dive with .. IANTD and all the other outfits only tell the great unwashed to dive with a low set point to keep them away from 02 at 6m ,, and i will tell you why ( they cant hold a stop that,s it ,,) all well and good, but we end up with divers that are worried shitless about having o2 with a ppo2 of 1.6 in the ccr , maybe that,s why you see lots of ccr divers passing out in 6m or less ,, LOW ppo2 kills as well , so best we all dive some place in the middle , but you need infomation to know were the middle is even ap say 1,3 for air dives on a ybod ,, OC and ppo2 as for diving OC the numbers started at 1.5ppo2, less .5 for diving in cold water less, .5 for a hard work .. and 1.6 for deco , we all know it is the best ppo2 to be on ,, for deco , keep you're eye on the cns clock , i can do that on the fly as i dive, its not hard ,,, well it could be hard if you only got a book to look them up in ,,, cos you were never told how to work out your cns per min .. yes we have computers to work out are CNS, but they cant look a head as you dive , i see 100s of divers swimming round in 30 40m with a ali 80 of 50% , same dive could be done with a half full 3L cylinder of o2, its not the divers fault that,s how he was told to do it ,, ppo2 of 50% at 6m= useless, for deco ,,, but hay all the word love's it ,,, its v safe if you cant hold a stop ,,, good for the mass , good for selling nitrox card, but its crap for deco,, you need twice as much deco gas .. all needs humping around = more shite hanging of a diver, more drag, more work, more gas used ,, and that,s be4 we even get to do the deco,, just my 2p i will stick with my ppo2 numbers, thank you ,, ccr 1.3 and 1.6 for deco . OC 1.4 / 1.45 max ppo2 on bottom deco 1.6ppo2 with well over a thousand dives on said numbers , i dont see why a should change now dive safe,
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15th February 2008, 00:08	#22 (permalink)
Gobfish1 RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Join Date: Apr 2005 Location: Manchester UK Posts: 410	Re: How much Deco Quote: (Originally Posted by Moray Brown) Confused Surely anyone carrying 50% will know to be on it from 21m and not 6m... only when you run a 1,6 pp2 for deco , if you run with the 1.2 bollox you wont be sucking on you're 50% at 21m will you ... you miss the window and spend the rest of your deco on a low ppo2 that ant much good for deco ,, this thread has a depth limit of 45 to 50m so one deco cylinder .. Yes and most of the deco is at 6m, Yes __________________ Steve G Apparently not the only gay diver in the village http://drinkingliberally.org/blogs/o...nzee-glock.gif http://www.scubatunes.com/audio/vol01/mp3/HiTech.mp3 Last edited by Gobfish1 : 15th February 2008 at 20:20.
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15th February 2008, 10:29	#23 (permalink)
Moray Brown CCR Training - MR Diving Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2006 Location: WMUK Posts: 261	Re: How much Deco I take your point, but your statement is a bit broad. Maybe they are MOD1 trained and are not experienced in raising set points for deco? If you are relating to O/C divers, maybe they only have a 50% ticket. If you relate of OC and CCR Trimix divers - who knows why they do it, but they do and if works for them then fair play. Quote: (Originally Posted by Gobfish1) only when you run a 1,6 pp2 for deco , if you run with the 1.2 bollox you wont be sucking on you 50% at 21m will you ... you miss the window and spend the rest of your deco on a low ppo2 that ant much good for deco ,, this thread has a depth limit of 45 to 50m so one deco cylinder .. Yes and most of the deco is at 6m, Yes
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15th February 2008, 16:52	#24 (permalink)
Gobfish1 RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Join Date: Apr 2005 Location: Manchester UK Posts: 410	Re: How much Deco MOD1 trained and are not experienced in raising set points for deco? big green button , simple i would think ,,, O/C divers, maybe they only have a 50% tick ,, yes ,, but should that stop then from thinking, my last post on this , im board with it ,, __________________ Steve G Apparently not the only gay diver in the village http://drinkingliberally.org/blogs/o...nzee-glock.gif http://www.scubatunes.com/audio/vol01/mp3/HiTech.mp3 Last edited by Gobfish1 : 15th February 2008 at 17:23.
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16th February 2008, 01:20	#25 (permalink)
tekdiver170 RBW Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Jan 2007 Location: Honolulu, HI Posts: 88	Re: How much Deco Quote: (Originally Posted by Gobfish1) think you will find you're only talking for divers over the pond .. all the divers i know run with 1,45 max bottom OC and 1,6 deco CCR run 1.3 or 1.4 and 1.5 1.6 deco on dives in less that 50m all this crap about low ppo2 is just for the unwashed ,, i have been diving nitrox and mix gas for 15 years ,, never had a problem with my ppo2 s or my deco .. IANTD used to teach the facts , but have had to throw in some bull shit to sell it's nitrox and mix bollox to the mass ,, just cos you were told by some guy it's so , dont make it fact ,,, as for deco tables i have about 8 of them on my computer plus a shit load.s of books with tables in take your pick they all give you a dif frigging number for a said dive ,,, i said play with the numbers for fun not to dive on in the other post ,, and i said you will get longer bottom time , like to see you do 60min at 50m on a set of 12L twins i never said a word about how much deco would be needed the art of diving mixgas seems to get's more diluted as the years pass bye ;;; knobs teaching knobs teaching knobs = BS Send three and four pence, we're going to a dance. It's good you have found a decompresssion plan that works for you, but you also have to take everything with a grain of salt before pushing that plan on everyone. The so called "Safe" PO2's were put in place base upon the % of people who were experiencing O2 tox symptoms in a chamber. One person may be a freak of nature and be perfectly fine to dive a 1.6PO2 for an entire 3 hour dive, others may start experiencing tox syptoms far sooner. Through experience I know what my limitations are. At a PO2 of 1.6 I start experiencing tox symptoms at 12-14 min. Scary $hit when you start convulsing at 20' while breathing O2 for 12min. After all someone said I should be safe until the 15 min. gas break. Not being the brightest in the bunch I still thought I should be safe at a 1.6 for 15 min, so lets try it again. Sure enough next dive same results. My CNS clock was not filled in fact it was only at around 50%. Through trial and error this happened 3 more times. Then I got smart and moved to CCR. Now I can run "cooler" breathing mixtures and still make it to the surface with the divers on OC. Now I run a 1.1-1.2 on the bottom and deco with 1.25-1.3. Knock on wood no more O2 toxicity = happier Chris. I would feel really bad if I gave someone the advice that said, in Europe O2 toxicity doesn't affect people the same way because we're on the other side of the ocean. Only to hear they later toxed while deco'ing at a PO2 of a 1.6. As has been said over and over, decompression is an art not a science. You have to find what works best for you. __________________ Diving is my therapy... keeps the voices in my head from getting louder. Good thing rebreathers have no bubbles, now I can hear them again. - Chris Liles www.oahuscubadiving.com www.hawaiitechnicaldivers.com
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16th February 2008, 03:22	#26 (permalink)
Gobfish1 RBW Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Join Date: Apr 2005 Location: Manchester UK Posts: 410	Re: How much Deco Quote: (Originally Posted by tekdiver170) It's good you have found a decompresssion plan that works for you, but you also have to take everything with a grain of salt before pushing that plan on everyone. The so called "Safe" PO2's were put in place base upon the % of people who were experiencing O2 tox symptoms in a chamber. One person may be a freak of nature and be perfectly fine to dive a 1.6PO2 for an entire 3 hour dive, others may start experiencing tox syptoms far sooner. hold on there m8 ,i never said or posted, Some one should dive on a gas with a ppo2 of 1.6 for 3 hours , i said i deco out at 1.6 ppo2, but if your read my post, i do say, keep an eye on you're CNS .. i did not say what i run my CNS to ,, i did not say run you cns clock to over 400% as you would do if you swam round for 180mins sucking on a gas with a ppo2 of 1.6 .. fooking madnass after all, i posted the ppo2s that i dive on ,, and have done forsome time .. one guy says its not safe to run more than a 1.2 ppo2 and i say that s bollox i dive 1.3 or 1.4 , and 1.6 for deco, i have done over a thousand dives on said ppo2 s to back that info up ,, i also said we should all pick a ppo2 some place in the middle and be safe .. Through experience I know what my limitations are. At a PO2 of 1.6 I start experiencing tox symptoms at 12-14 min. Scary when you start convulsing at 20' while breathing O2 for 12min. After all someone said I should be safe until the 15 min. gas break. Not being the brightest in the bunch I still thought I should be safe at a 1.6 for 15 min, so lets try it again. Sure enough next dive same results. My CNS clock was not filled in fact it was only at around 50%. Through trial and error this happened 3 more times. Then I got smart and moved to CCR. Now I can run "cooler" breathing mixtures and still make it to the surface with the divers on OC. Now I run a 1.1-1.2 on the bottom and deco with 1.25-1.3. Knock on wood no more O2 toxicity = happier Chris. experiencing tox symptoms now that's something you dont get to hear Most just tox ,, if you feel you're in danger of having a tox when you CNS clock hit only 50% and you're ppo2 is up over 1.3 i would think you may need to talk with a diving Doc,,, it ant the norm ,, please if you have seen a DOC what did he say I would feel really bad if I gave someone the advice that said, in Europe O2 toxicity doesn't affect people the same way because we're on the other side of the ocean. Only to hear they later toxed while deco'ing at a PO2 of a 1.6. yes so would i ,, that's why i said keep you're eye on you're CNS clock and we all know that you should not push it passed 80% says so in the book if other diver run CNS s to well over 200% and are just fine , on matter .. As has been said over and over, decompression is an art not a science. You have to find what works best for you. my post were not about telling someone to dive on a said ppo2 or deco ... i was posting to make a point , point was get all the infomation about mixgas diving , then make your choice ,, dont take it as fact just cos some guy says it s so on the internet ,, that go's for what in my post to , im v happy to see divers use what ever ppo2 they want , but im not happy when some one pops in and says diving a ppo2 above 1.2 is unsafe ,, remember this post was about a chap wanting to dive ccr in about 50m with limited deco ,, the next new bunch of trimix diver, will be on the boards soon telling us all its not safe to dive a ppo2 above .9... until a few of them passout in 6m or less ,, 100.000 divers, doing just fine, if one guy has a hit on a ppo2 of 1.3+ are we all then fooked is that it ,,, thousands of scuba diver on holiday in the reasea / meldives right now swimming round on a nitrox 36% in 30m of water ,,, are they all dancing the jig , convulsing at 20' while breathing O2 for 12min. worrying shit m8 so whats you're run time,s on your dives end CNS tell me more,, how do you manage you're dives ,,, do you use a full face mask , even a 120min dive at 1.2ppo2 will put you're cns count over you're 50% so what do you do .. tell us about you're tox symptoms number of time you have had them ... how long can you last on a ppo2 of 1,5 ( .83 much better than 2,2 ) can you run a full 80%/100% cns clock on 1.2/1.3 ppo2 , is it just the 1.6 you cant hack .. ps I see you're in Honolulu, so no need to worry about o2 hit chris , them big Tiger Shark,s will get you first ,, interesting post by the way, best reply to date, __________________ Steve G Apparently not the only gay diver in the village http://drinkingliberally.org/blogs/o...nzee-glock.gif http://www.scubatunes.com/audio/vol01/mp3/HiTech.mp3 Last edited by Gobfish1 : 16th February 2008 at 06:45.
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17th February 2008, 03:02	#27 (permalink)
tekdiver170 RBW Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Jan 2007 Location: Honolulu, HI Posts: 88	Re: How much Deco I wasn't trying to say you were preaching the know-all-end-all. It's unfortunate we have people who will read something and assume it right (for them) no matter where the info comes from. Maybe it's because I live in lawsuit happy America. I mean when we have people fill out Liability Releases for dive classes out here we have them first sign a Liability Waiver saying they won't sue us for getting writers cramps or carpel tunnel. Now tiger sharks, are those the fury ones? They're kind'a cuddly. A little about my tox experiences. All of my O2 tox issues have happened on OC to date (knock on wood). They occurred on a variety of different dive profiles. The first being a dive to :30min dive to 150 on 25%, then 50% at 70' and 100% at 20'. I don't remember the exact profile we used for deco something around 6min at 70' 4min at 60' 1min at 50 1min at 40 3min at 30' and then switch to O2 @ 20' for 12min with a 3min planned ascent. O2 symptoms for all cases were the same. Diaphragm contractions/convulsions. Best way to describe it, you have no control over your breather pattern, your body just does what it wants and it's usually small short breaths. Immediate response was to switch to lowest PO2 (backgas) and try not to aspirate water. Over the next year or so it happened another 4 times, most of them on a little bit deeper profile. Something like 200' on 18/45 for 25min. Switch to 35/25 at 120' for 2min every 10' until 70' switch to 50% for 8min at 70' 6min at 60' 2 min at 50 2min at 40 and 3 min. gas break at 30' and O2 at 20' for 15min and a 5 min ascent (Ascent=gas break). (Tox symp started on 100% at 20' 12-14 min.) The worst case was a dive to 230' for :25 on 16/45. Switch to 35/25 at 120 3min every 10' until 80' 3min. gas break on backgas. At 70' 50% for 12min. 60' for 6min 50' for 3min 40' for 3 min 6min Gas break at 30'. By this time I started to believe in taking earlier gas breaks to the plan called for 10min on and 5 mins off O2 at 20' for 25min with a 5 min ascent. I never made it to the 20' stop able to use this idea. I experienced the most severe contractions to this day 5 min into my 60' stop. Switched to backgas until 40' stop then back to 50%. Gas break at 30', then tried to go back on 02 at 20' only to have symptoms again after 4 1/2 min. I then did the rest of my deco doing 3min on and 3 min off O2, extending my deco time at 20 by 10min. After this dive I did not do another deco dive until I got comfortable on my Rebreather. As I said knock on wood I have not had issues since, but I am super paranoid about it happening again and practice, practice, practice bailout techniques just in case. There was a post by a guy last year who had the same type of O2 symptoms but he stayed on his loop a little too long and loss consciousness after less than a min of diaphragm convulsions. He was lucky and had a great buddy who was right there to assist. He lived. I tried to contact him for some further info but he declined to answer back. __________________ Diving is my therapy... keeps the voices in my head from getting louder. Good thing rebreathers have no bubbles, now I can hear them again. - Chris Liles www.oahuscubadiving.com www.hawaiitechnicaldivers.com
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17th February 2008, 05:36	#28 (permalink)
tekdiver170 RBW Member Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Jan 2007 Location: Honolulu, HI Posts: 88	Re: How much Deco Quote: (Originally Posted by Gobfish1) ,,, do you use a full face mask , even a 120min dive at 1.2ppo2 will put you're cns count over you're 50% so what do you do .. tell us about you're tox symptoms number of time you have had them ... how long can you last on a ppo2 of 1,5 ( .83 much better than 2,2 ) can you run a full 80%/100% cns clock on 1.2/1.3 ppo2 , is it just the 1.6 you cant hack .. I have not gone as far as a full face mask. On my Rebreather I have done dives in the 150 min. range at a 1.3 in shallower water < 100' and so far have not had an issue. But I have not yet pushed the limits at 1.3. This leads me to believe 2 things. One is that my body just doesn't like PO2 at a 1.6, or maybe it's diving at deeper depths that leads to my issues at a higher PO2. Most of my deeper dives have bottom times in the 30 min. range. I dive with OC divers so this is what they're able to do with the tank sizes we dive out here in Hawaii. It's funny even though I've done 150 min+ dives on my Rebreather in shallower water with a PO2 of a 1.3 but it's our deco dives I get more nervous about an O2 hit while on my deco at a 1.25 for only around an hour. __________________ Diving is my therapy... keeps the voices in my head from getting louder. Good thing rebreathers have no bubbles, now I can hear them again. - Chris Liles www.oahuscubadiving.com www.hawaiitechnicaldivers.com
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17th February 2008, 10:47	#29 (permalink)
Abbo Nicholas Smith Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 460	Re: How much Deco Gobfish, I would assume that if we had results of tests on how many people ox toxed at what depth, we would see a bell curve. Right in the middle, at the peak occurance, would be the average PO2 at which people started break dancing. At that PO2, half the people would be safe and half would not. One standard deviation below that average, 84% of people would be safe. Two standard deviations below and 98% of people would be safe. What percentage of people would die using the PO2 you use? - because that percentage is never zero. The question is 'what fatality rate is acceptable?' Don't ask the diver: ask his wife. And don't ask me, as I wouldn't want those people on my conscience. I would love to see those statistics, though, if anyone knows where to get them: what is the PO2 tolerance limit for the average person, what is one standard deviation, and is the relationship a normal distribution? I don't know what my PO2 tolerance is -I've never had a hit - and I don't have much of a feeling for what the day-to-day variation is. I don't like taking risks where the effect is unknown. As I see it, with PO2s the benefits of taking those risks are negligible. But I'm sure you're right that I'm probably a very long way inside my tolerance limits.
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17th February 2008, 11:04	#30 (permalink)
*EBT* Apprentice Luddite Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: UK, Brighton Posts: 2,115	Re: How much Deco Theres a cracking book, "oxygen and the diver" by kenneth donald..... he did research into O2 tolerance. Theres an excerpt of it HERE The long and short of it is tolerance varies widely between individuals and even for the same individual over time. So we tend towards conservative limits, to reduce the % chance of a problem. Of course this means you can get away with higher limits, but with higher risk. Its a balancing act...... __________________ Eagles May Soar, but weasels don't get sucked into jet engines! RBW Terms of service
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