hg frogman
Contributor
Limits for air diving from my personal experience
Diving air down to 45 meters/150 feet in open water dives (no penetration) I am not worried by narcosis. This attitude comes from my inner perceptions (no symptoms of narcosis) and from no significant evil specific to narcosis ever arising at this range of depth in my experience (about 200 air dives deeper than 40 meters/130 feet). Some of my buddies experienced mild symptoms (eg music in their mind) while diving with me at 40 meters, but they behaved all right. Also we did some mistakes when we had less experience - like not stopping at 40 meters/130 feet to perform a narcosis test before getting any deeper.
Between 45 meters/150 feet and 55 meters/183 feet I take air diving very seriously - I never felt impaired but I tell myself that I am most probably significantly slowed down. So I only do open water (no penetration) air dives to these depths, and only with buddies I know well, and with everything in good conditions (sea, viz, temperature, currents, buddies and myself: fit, slept well, not stressed, well hydrated, no alcohol ...). And systematically we stop at 40 meters/130 feet to perform a test of narcosis before going deeper (or not).
I did a handful of air dives between 55 meters/183 feet and 65 meters/215 feet. I didn't feel impaired (that's subjective, objective testing probably would have shown severe slowing down) apart from a over-cautious sort of mild paranoia. I think it's a bit too much on the edge (akin from South Col to the summit of Everest) for the amount of risk I am ready to take. Twice I had dive buddies impaired and I had to assist them to go up. Same criteria than above (but even more adamant) about buddies, conditions and narcosis test. But I try to keep these dives exceptional.
Deeper than 65 meters/215 feet I never went (and I don't want to) with air. I have no idea of the subjective effects of narcosis on me at this depth (it's like drugs, I am not interested in knowing these effects anyway) but OxTox risk scares me enough to not go. I know fellow divers who dive deeper than that with air, but for very very short bounces. I have been amazed to read about those air divers penetrating a submarine at 220 feet : I'd never do that !
Limits for air diving from a law perspective
- In France it's 60 meters/200 feet (if you are adequately certified) with your deco also on air (or on Nitrox if you have this additional certification)
- In Great Britain it's 50 meters/165 feet (or more ?) for BSAC
- For TDI it's 55 meters/183 feet
- For DSAT it's 50 meters/165 feet
- In Egypt it's 40 meters for recreational certs (and 55 meters for tech certs, eg TDI, if I am not wrong)
Limits for air diving from an historic and environmental perspective
- SCUBA diving began around 1943 with Jacques Cousteau in the Mediterranean sea, where the interesting dives (especially for the fixed fauna) are mostly 40 meters/130 feet to 60 meters+/200 feet+ deep. Deco (air) diving has been the norm there for decades. That has set (and still does) the kind of training, and the limits for air diving, in Europe.
- In the Caribbean there is plenty of stuff to see in shallow waters. That, plus the RSTC agencies philosophy (which is not the topic here), has set the limits for air diving shallower (eg 40 meters/130 feet) for the so-called "recreational divers" (a notion that doesn't exist in Europe : all leisure divers, even those diving with Heliox rebreathers, are called "recreational" there).
- In France many divers still dive air down to 60 meters/200 feet (for open water dives) but there is a growing minority of French divers systematically using Trimix for (no penetration) dives deeper than 50 meters/165 feet. They often tend to use less helium than in some other places, though (typically Tx20/25 for a 60 meters/200 feet open ocean dive, with an END = 40 meters/130 feet).
- French cave divers and French divers penetrating wrecks (that's not all wreck divers) have their own set of rules.
Conclusion
I am probably a bit optimistic about narcosis, given I come from a country where diving is not felt and done the same way than, for example, most North Americans do. And also given that my diving experience has limits (mostly temperate and tropical waters with decent viz). On the other hand, many North Americans are likely to be a bit pessimistic about narcosis. And in any country these things evolve in time. So finally I would say, deep air diving begins at 40 or 45 meters (130 or 150 feet) and finishes at 55 or 60 meters (183 or 200 feet) from where in most cases it's better to dive trimix in my opinion (and it may well be a good idea to add some Helium as soon as 45 meters/150 feet if one can afford it). Same than for rock climbing : pioneers climbed with nailed shoes but we don't have to do the same - but in the other hand diving the Doria with only 100 dives under one's belt because one uses trimix is probably tempting the devil, as DCBC rightly says - and air diving, unlike nailed shoes for climbing, isn't so bad finally, it's simple and light, provided one doesn't go behind one's and buddies' limits.
Last comment
In several threads from this board I found that those who are against "deep air diving" are much more normative than their antagonists. Anyway, thanks to the OP for giving us an opportunity for clarifying what we mean by "deep air".
Diving air down to 45 meters/150 feet in open water dives (no penetration) I am not worried by narcosis. This attitude comes from my inner perceptions (no symptoms of narcosis) and from no significant evil specific to narcosis ever arising at this range of depth in my experience (about 200 air dives deeper than 40 meters/130 feet). Some of my buddies experienced mild symptoms (eg music in their mind) while diving with me at 40 meters, but they behaved all right. Also we did some mistakes when we had less experience - like not stopping at 40 meters/130 feet to perform a narcosis test before getting any deeper.
Between 45 meters/150 feet and 55 meters/183 feet I take air diving very seriously - I never felt impaired but I tell myself that I am most probably significantly slowed down. So I only do open water (no penetration) air dives to these depths, and only with buddies I know well, and with everything in good conditions (sea, viz, temperature, currents, buddies and myself: fit, slept well, not stressed, well hydrated, no alcohol ...). And systematically we stop at 40 meters/130 feet to perform a test of narcosis before going deeper (or not).
I did a handful of air dives between 55 meters/183 feet and 65 meters/215 feet. I didn't feel impaired (that's subjective, objective testing probably would have shown severe slowing down) apart from a over-cautious sort of mild paranoia. I think it's a bit too much on the edge (akin from South Col to the summit of Everest) for the amount of risk I am ready to take. Twice I had dive buddies impaired and I had to assist them to go up. Same criteria than above (but even more adamant) about buddies, conditions and narcosis test. But I try to keep these dives exceptional.
Deeper than 65 meters/215 feet I never went (and I don't want to) with air. I have no idea of the subjective effects of narcosis on me at this depth (it's like drugs, I am not interested in knowing these effects anyway) but OxTox risk scares me enough to not go. I know fellow divers who dive deeper than that with air, but for very very short bounces. I have been amazed to read about those air divers penetrating a submarine at 220 feet : I'd never do that !
Limits for air diving from a law perspective
- In France it's 60 meters/200 feet (if you are adequately certified) with your deco also on air (or on Nitrox if you have this additional certification)
- In Great Britain it's 50 meters/165 feet (or more ?) for BSAC
- For TDI it's 55 meters/183 feet
- For DSAT it's 50 meters/165 feet
- In Egypt it's 40 meters for recreational certs (and 55 meters for tech certs, eg TDI, if I am not wrong)
Limits for air diving from an historic and environmental perspective
- SCUBA diving began around 1943 with Jacques Cousteau in the Mediterranean sea, where the interesting dives (especially for the fixed fauna) are mostly 40 meters/130 feet to 60 meters+/200 feet+ deep. Deco (air) diving has been the norm there for decades. That has set (and still does) the kind of training, and the limits for air diving, in Europe.
- In the Caribbean there is plenty of stuff to see in shallow waters. That, plus the RSTC agencies philosophy (which is not the topic here), has set the limits for air diving shallower (eg 40 meters/130 feet) for the so-called "recreational divers" (a notion that doesn't exist in Europe : all leisure divers, even those diving with Heliox rebreathers, are called "recreational" there).
- In France many divers still dive air down to 60 meters/200 feet (for open water dives) but there is a growing minority of French divers systematically using Trimix for (no penetration) dives deeper than 50 meters/165 feet. They often tend to use less helium than in some other places, though (typically Tx20/25 for a 60 meters/200 feet open ocean dive, with an END = 40 meters/130 feet).
- French cave divers and French divers penetrating wrecks (that's not all wreck divers) have their own set of rules.
Conclusion
I am probably a bit optimistic about narcosis, given I come from a country where diving is not felt and done the same way than, for example, most North Americans do. And also given that my diving experience has limits (mostly temperate and tropical waters with decent viz). On the other hand, many North Americans are likely to be a bit pessimistic about narcosis. And in any country these things evolve in time. So finally I would say, deep air diving begins at 40 or 45 meters (130 or 150 feet) and finishes at 55 or 60 meters (183 or 200 feet) from where in most cases it's better to dive trimix in my opinion (and it may well be a good idea to add some Helium as soon as 45 meters/150 feet if one can afford it). Same than for rock climbing : pioneers climbed with nailed shoes but we don't have to do the same - but in the other hand diving the Doria with only 100 dives under one's belt because one uses trimix is probably tempting the devil, as DCBC rightly says - and air diving, unlike nailed shoes for climbing, isn't so bad finally, it's simple and light, provided one doesn't go behind one's and buddies' limits.
Last comment
In several threads from this board I found that those who are against "deep air diving" are much more normative than their antagonists. Anyway, thanks to the OP for giving us an opportunity for clarifying what we mean by "deep air".
Last edited: