How deep to you dive on air diluent?

nskdrs · 22nd January 2008, 07:51

I chose OC when He was not available, trip on short notice, tried one week to find He, that was 2 dives a day, 50m+, 30min BT,
something I really try to avoid.

Mark Chase · 22nd January 2008, 07:53

As above.

There are only a few who have addressed the real issue, which is, how deep are you prepared to go if Helium is not available?

Most agree that if it is, then use it.

However as i understand the thread the real underlying question is, why are you concerned about using helium? It sounds as if you do have access to helium but don't want to use it.

The fact that some of us will venture deep on air if needs must doesn't detract from the fact its dangerous. I had a very bad narcosis hit when I thought my buddy was trying to kill himself. I was on OC air at about 60m in clear blue water off Gozo. It was a horrible experience.

When the dive is going well deep air is easy and even fun but when things get serious its a bloody awful gas to be on.

If the question is, at what max depth do you consider Air to be a safe gas?

25-30m in the UK and similar conditions 35-40m in the blue stuff.

Deeper than that and i wouldn't do any sort of challenging dive.

ATB

Mark

grazie42 · 22nd January 2008, 10:24

One of the biggest factors in my decision to go CCR was that He becomes an "every dive gas"...

What finally tipped me over was spending the summer doing 150ft dives on OC air and then splurging on mix for a 180ft dive and finding the dive so easy that it felt like "cheating"...Granted, bottom temps here are about 4-6C year-round and it´s basically a night dive but still...I just decided that I wasn´t going to keep cheating myself out of good dives because I was to cheap to pay for the gas...

Everyone is different but I don´t find that He is too cold as a ds-gas until +40% and even then it isn´t that bad...On OC it was more that I didn´t want to waste expensive gas on keeping my ds wrinkle-free than anything else...

In blue, warm water I´d propably go beyond 150ft but not much...never if He was available...just do a dive on mix with someone OC or CCR and see for yourself!

**PhilSiswick** · 22nd January 2008, 10:51

Quote: (Originally Posted by grazie42)

One of the biggest factors in my decision to go CCR was that He becomes an "every dive gas"...

What finally tipped me over was spending the summer doing 150ft dives on OC air and then splurging on mix for a 180ft dive and finding the dive so easy that it felt like "cheating"...Granted, bottom temps here are about 4-6C year-round and it´s basically a night dive but still...I just decided that I wasn´t going to keep cheating myself out of good dives because I was to cheap to pay for the gas...

Everyone is different but I don´t find that He is too cold as a ds-gas until +40% and even then it isn´t that bad...On OC it was more that I didn´t want to waste expensive gas on keeping my ds wrinkle-free than anything else...

In blue, warm water I´d propably go beyond 150ft but not much...never if He was available...just do a dive on mix with someone OC or CCR and see for yourself!

I may be more prone to narcosis than others, or just feel less happy about it, but I decided that I wasn't happy to go deeper than 40m in the UK on air after some 'interesting' dives to 45 and 50 (50+ dives). Nothing major, just a continual sense of 'I don't want to be here' that spoilt the dive.

That decided me for mix, but the logistics (and less importantly, the cost) put me off. So, I went CCR so that I could use mix on every dive. I'm only a year or so in, so have little experience yet, but the difference to my diving in the 40+ bracket has been stunning. More enjoyable, more memorable, more relaxed overall.

Can't recommend it enough. I'm not saying I'm ready for deeper dives yet, but I'm happy as Larry in the 45-50 bracket.

Cheers,

**Gill Envy** · 22nd January 2008, 15:33

Quote: (Originally Posted by Mark Chase)

As above.

There are only a few who have addressed the real issue, which is, how deep are you prepared to go if Helium is not available?

Most agree that if it is, then use it.

yes, and I'd still like to hear more responses to that.

Quote: (Originally Posted by Mark Chase)

However as i understand the thread the real underlying question is, why are you concerned about using helium? It sounds as if you do have access to helium but don't want to use it.

When I started this thread I figured it would quickly become a thread about the virtues of helium. In the course of reading through all the responses i'm being nudged over the threshold of resistance and have even contacted my instructor about possibilities. still, the places where I tend to dive the deepest are in warm blue water where there are lots of critters still to see and not much challenge...it's a few times a year at best, and access to helium will be particularly limited in those places. So I've asked what folks limits are when they can't get it because i'm getting the feeling that once I make the transition in thinking and training i'll be using it pretty much all the time I can get ahold of it.

the final hurdle will be dealing with the fact that when my wife and I first got into rebreathers, out of a desire to set some kind of limit, she made me promise her i'd never go there. Sounds absurd perhaps but that's life in partnership. If you think i'm resistant, you should hear her! the trimix mod 1 thread brought out the reality for me that had we been introduced to it as a gas that has benefits even within recreational limits (which many folks seem to experience), in the context of mod 1 both my wife and I might just have gotten past our mistrust. Seeing it as a deep and dangerous gas has probably been the stumbling block. I know it sounds crazy to anyone who has been using it, but for those who have not, there is still quite an air of fear and misunderstanding around it. we all come around to expanding our comfort zones in our own time.

Quote: (Originally Posted by Mark Chase)

The fact that some of us will venture deep on air if needs must doesn't detract from the fact its dangerous. I had a very bad narcosis hit when I thought my buddy was trying to kill himself. I was on OC air at about 60m in clear blue water off Gozo. It was a horrible experience.

When the dive is going well deep air is easy and even fun but when things get serious its a bloody awful gas to be on.

If the question is, at what max depth do you consider Air to be a safe gas?

25-30m in the UK and similar conditions 35-40m in the blue stuff.

Deeper than that and i wouldn't do any sort of challenging dive.

ATB

Mark

I'm getting that loud and clear, had plenty of experience on OC that concurs and very much appreciate the caution.

OceanOpportunity · 22nd January 2008, 18:04

I too can appreciate having had made a degree of promises to my other half. A consideration might be to stick with normoxic or slightly hyperoxic trimix diluents, so depth is still limited by virtue of high PO2's. This would of course be safer than diving air diluent to the same depths, and in reality a few percentage helium for 'short' dives isnt going to do much to your deco obligations...may even shorten them! OC Bailout to your dil is the same, no need to worry about hypoxia, and no need to worry about logistics for diluent gas switches to go very deep. Of course, what helium does do for me (and many) is afford such a clear head that taking a next step almost seems too easy. In general though, if you've made dives to say the 150-175 range with air diluent, and have decided that that is an acceptable maximum depth for the diving you do, incorporating hyperoxic/normoxic diluent is a smart step to ere on the side of caution.

Aside from that, the depth item is a matter of personal comfort and consideration. In warm, clear, stree-free diving, I have no problem with 165fsw, and have ventured to 180fsw on air dil. Cold dark water, I wouldn't even think about it as I know my narcotic threshold is much less than that to maintain a degree of competency.

Nailer99 · 22nd January 2008, 18:10

Quote: (Originally Posted by Gill Envy)

Nailer,
Now you've done it...you just had to go and invite me in on a class...the siren call is beginning to take hold

.

well we'll have to see how this unfolds. I'd definitely be up for a dive soon in any case. if you are interested, drop me a line.
g

PM Sent.

***EBT*** · 22nd January 2008, 18:59

No one said you had to use a hypoxic dil.... theres 21/35 (easily snaffled off oc buddies), 20/40 etc....

Ant Slegg · 22nd January 2008, 20:00

As a European waters diver with some experience in warmer, clearer waters (i.e. the Red Sea) I'm not convinced by the argument that being in the clear stuff means less narcs. I dived the San Francisco Maru in Chuuk OC on air with a max depth of 58m. the narcosis is still there it's just that in the cold, clear stuff (i.e. NW Scotland) there's a lot if stuff that niggles you i.e cold spots in undersuits, slight leaks and your general stress levels are higher. I feel all this makes narcosis feel worse. I dived a small cave called the Bottle in Gozo and despite the max depth (>50m) felt fine until we went inside (I did a cavern course in South Wales a little before that so it wasn't just being in the cave). The water inside was cold and the divers ahead of me had reduced the vis'. The narcosis hit me like a hammer.

For my money narcosis affects the brain but also has a start there. Not scientific just my experience...

The solution is He.

Dave Sutton · 22nd January 2008, 20:29

Quote: (Originally Posted by Mark Chase)

As above.

There are only a few who have addressed the real issue, which is, how deep are you prepared to go if Helium is not available?

Feet: Historically 220 in cold water, 250 in warm. Today? Maybe 200 and 220..... older and wiser (a little wiser anyway).

Dave

.

22nd January 2008, 07:51	#71 (permalink)
nskdrs New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Classic Kiss Not Bought Yet Join Date: Sep 2005 Location: germany Posts: 80	Re: How deep to you dive on air diluent? I chose OC when He was not available, trip on short notice, tried one week to find He, that was 2 dives a day, 50m+, 30min BT, something I really try to avoid. Last edited by nskdrs : 22nd January 2008 at 07:56.
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22nd January 2008, 07:53	#72 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,558	Re: How deep to you dive on air diluent? As above. There are only a few who have addressed the real issue, which is, how deep are you prepared to go if Helium is not available? Most agree that if it is, then use it. However as i understand the thread the real underlying question is, why are you concerned about using helium? It sounds as if you do have access to helium but don't want to use it. The fact that some of us will venture deep on air if needs must doesn't detract from the fact its dangerous. I had a very bad narcosis hit when I thought my buddy was trying to kill himself. I was on OC air at about 60m in clear blue water off Gozo. It was a horrible experience. When the dive is going well deep air is easy and even fun but when things get serious its a bloody awful gas to be on. If the question is, at what max depth do you consider Air to be a safe gas? 25-30m in the UK and similar conditions 35-40m in the blue stuff. Deeper than that and i wouldn't do any sort of challenging dive. ATB Mark __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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22nd January 2008, 10:24	#73 (permalink)
grazie42 Eager Newbie! Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Jun 2005 Location: Sweden Posts: 29	Re: How deep to you dive on air diluent? One of the biggest factors in my decision to go CCR was that He becomes an "every dive gas"... What finally tipped me over was spending the summer doing 150ft dives on OC air and then splurging on mix for a 180ft dive and finding the dive so easy that it felt like "cheating"...Granted, bottom temps here are about 4-6C year-round and it´s basically a night dive but still...I just decided that I wasn´t going to keep cheating myself out of good dives because I was to cheap to pay for the gas... Everyone is different but I don´t find that He is too cold as a ds-gas until +40% and even then it isn´t that bad...On OC it was more that I didn´t want to waste expensive gas on keeping my ds wrinkle-free than anything else... In blue, warm water I´d propably go beyond 150ft but not much...never if He was available...just do a dive on mix with someone OC or CCR and see for yourself! Last edited by grazie42 : 22nd January 2008 at 10:29.
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22nd January 2008, 10:51	#74 (permalink)
PhilSiswick WSKD 0001 Current Rebreather/s: Evolution Other Rebreather/s: Inspiration Vision Join Date: Apr 2006 Location: Oxford, UK Posts: 922	Re: How deep to you dive on air diluent? Quote: (Originally Posted by grazie42) One of the biggest factors in my decision to go CCR was that He becomes an "every dive gas"... What finally tipped me over was spending the summer doing 150ft dives on OC air and then splurging on mix for a 180ft dive and finding the dive so easy that it felt like "cheating"...Granted, bottom temps here are about 4-6C year-round and it´s basically a night dive but still...I just decided that I wasn´t going to keep cheating myself out of good dives because I was to cheap to pay for the gas... Everyone is different but I don´t find that He is too cold as a ds-gas until +40% and even then it isn´t that bad...On OC it was more that I didn´t want to waste expensive gas on keeping my ds wrinkle-free than anything else... In blue, warm water I´d propably go beyond 150ft but not much...never if He was available...just do a dive on mix with someone OC or CCR and see for yourself! I may be more prone to narcosis than others, or just feel less happy about it, but I decided that I wasn't happy to go deeper than 40m in the UK on air after some 'interesting' dives to 45 and 50 (50+ dives). Nothing major, just a continual sense of 'I don't want to be here' that spoilt the dive. That decided me for mix, but the logistics (and less importantly, the cost) put me off. So, I went CCR so that I could use mix on every dive. I'm only a year or so in, so have little experience yet, but the difference to my diving in the 40+ bracket has been stunning. More enjoyable, more memorable, more relaxed overall. Can't recommend it enough. I'm not saying I'm ready for deeper dives yet, but I'm happy as Larry in the 45-50 bracket. Cheers, __________________ Phil No comment on open circuit... it's an evolutionary dead end not really worth discussing here. Dave Sutton, 2007 I have always felt that the dive I am on is not nearly important as the dives I plan to be on the rest of my life. Tom Rose, 2007 www.hugsac.org.uk
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22nd January 2008, 15:33	#75 (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: How deep to you dive on air diluent? Quote: (Originally Posted by Mark Chase) As above. There are only a few who have addressed the real issue, which is, how deep are you prepared to go if Helium is not available? Most agree that if it is, then use it. yes, and I'd still like to hear more responses to that. Quote: (Originally Posted by Mark Chase) However as i understand the thread the real underlying question is, why are you concerned about using helium? It sounds as if you do have access to helium but don't want to use it. When I started this thread I figured it would quickly become a thread about the virtues of helium. In the course of reading through all the responses i'm being nudged over the threshold of resistance and have even contacted my instructor about possibilities. still, the places where I tend to dive the deepest are in warm blue water where there are lots of critters still to see and not much challenge...it's a few times a year at best, and access to helium will be particularly limited in those places. So I've asked what folks limits are when they can't get it because i'm getting the feeling that once I make the transition in thinking and training i'll be using it pretty much all the time I can get ahold of it. the final hurdle will be dealing with the fact that when my wife and I first got into rebreathers, out of a desire to set some kind of limit, she made me promise her i'd never go there. Sounds absurd perhaps but that's life in partnership. If you think i'm resistant, you should hear her! the trimix mod 1 thread brought out the reality for me that had we been introduced to it as a gas that has benefits even within recreational limits (which many folks seem to experience), in the context of mod 1 both my wife and I might just have gotten past our mistrust. Seeing it as a deep and dangerous gas has probably been the stumbling block. I know it sounds crazy to anyone who has been using it, but for those who have not, there is still quite an air of fear and misunderstanding around it. we all come around to expanding our comfort zones in our own time. Quote: (Originally Posted by Mark Chase) The fact that some of us will venture deep on air if needs must doesn't detract from the fact its dangerous. I had a very bad narcosis hit when I thought my buddy was trying to kill himself. I was on OC air at about 60m in clear blue water off Gozo. It was a horrible experience. When the dive is going well deep air is easy and even fun but when things get serious its a bloody awful gas to be on. If the question is, at what max depth do you consider Air to be a safe gas? 25-30m in the UK and similar conditions 35-40m in the blue stuff. Deeper than that and i wouldn't do any sort of challenging dive. ATB Mark I'm getting that loud and clear, had plenty of experience on OC that concurs and very much appreciate the caution. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°> Last edited by Gill Envy : 22nd January 2008 at 15:45.
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22nd January 2008, 18:04	#76 (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: 524	Re: How deep to you dive on air diluent? I too can appreciate having had made a degree of promises to my other half. A consideration might be to stick with normoxic or slightly hyperoxic trimix diluents, so depth is still limited by virtue of high PO2's. This would of course be safer than diving air diluent to the same depths, and in reality a few percentage helium for 'short' dives isnt going to do much to your deco obligations...may even shorten them! OC Bailout to your dil is the same, no need to worry about hypoxia, and no need to worry about logistics for diluent gas switches to go very deep. Of course, what helium does do for me (and many) is afford such a clear head that taking a next step almost seems too easy. In general though, if you've made dives to say the 150-175 range with air diluent, and have decided that that is an acceptable maximum depth for the diving you do, incorporating hyperoxic/normoxic diluent is a smart step to ere on the side of caution. Aside from that, the depth item is a matter of personal comfort and consideration. In warm, clear, stree-free diving, I have no problem with 165fsw, and have ventured to 180fsw on air dil. Cold dark water, I wouldn't even think about it as I know my narcotic threshold is much less than that to maintain a degree of competency. __________________ 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 January 2008, 18:10	#77 (permalink)
Nailer99 Vita Brevis Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jan 2007 Location: Seattle, WA, USA Posts: 201	Re: How deep to you dive on air diluent? Quote: (Originally Posted by Gill Envy) Nailer, Now you've done it...you just had to go and invite me in on a class...the siren call is beginning to take hold . well we'll have to see how this unfolds. I'd definitely be up for a dive soon in any case. if you are interested, drop me a line. g PM Sent. Last edited by Nailer99 : 22nd January 2008 at 18:21.
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22nd January 2008, 18:59	#78 (permalink)
*EBT* Apprentice Luddite Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: UK, Brighton Posts: 1,931	Re: How deep to you dive on air diluent? No one said you had to use a hypoxic dil.... theres 21/35 (easily snaffled off oc buddies), 20/40 etc.... __________________ Eagles May Soar, but weasels don't get sucked into jet engines! Rebreather World Terms of service Real diving t-shirts for real divers
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22nd January 2008, 20:00	#79 (permalink)
Ant Slegg Still Learning.... Current Rebreather/s: Ouroboros Other Rebreather/s: Ouroboros Join Date: Nov 2005 Location: Grevenmacher, Luxembourg Posts: 167	Re: How deep to you dive on air diluent? As a European waters diver with some experience in warmer, clearer waters (i.e. the Red Sea) I'm not convinced by the argument that being in the clear stuff means less narcs. I dived the San Francisco Maru in Chuuk OC on air with a max depth of 58m. the narcosis is still there it's just that in the cold, clear stuff (i.e. NW Scotland) there's a lot if stuff that niggles you i.e cold spots in undersuits, slight leaks and your general stress levels are higher. I feel all this makes narcosis feel worse. I dived a small cave called the Bottle in Gozo and despite the max depth (>50m) felt fine until we went inside (I did a cavern course in South Wales a little before that so it wasn't just being in the cave). The water inside was cold and the divers ahead of me had reduced the vis'. The narcosis hit me like a hammer. For my money narcosis affects the brain but also has a start there. Not scientific just my experience... The solution is He. __________________ Ant' S Learning to dive since 1990...
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22nd January 2008, 20:29	#80 (permalink)
Dave Sutton Membership Cancelled Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,637	Re: How deep to you dive on air diluent? Quote: (Originally Posted by Mark Chase) As above. There are only a few who have addressed the real issue, which is, how deep are you prepared to go if Helium is not available? Feet: Historically 220 in cold water, 250 in warm. Today? Maybe 200 and 220..... older and wiser (a little wiser anyway). Dave . Last edited by Dave Sutton : 22nd January 2008 at 20:31.
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