Max optimal depth on air, narcosis related

[elan]

I have a question to those who did many dives past 100' and observe others at those depth. According to your experience what would be the max depth on air you would suggest to set as a limit. So far I have not been below 100' though did dives in 90' range in cold water. I was able to do math calculations fairly quick so I think I was not narced.

Would it be wise to limit the depth to 100' and just get the training for using HE mixes if necessity to go past 100' arises (like diving Arabia @ Tobermory). The depth is not interesting for me now. Most of the time so far I tend to work on my skills at this time but do not forget about the fun part.

Thanks a lot.

 

[SailNaked]

many dives have been made to 200' on air, it is not usually done any more. not sure what the question is? lets assume you are just curious about deep diving, if you have been to 100 then 110 or 130 would not be much different and yes you would need to be certified to safely dive any deeper. As I understand it the learning curve gets steep after 130 and should not be taken lightly. if you wish to learn about it, contact your local tech diving instructor and he/she will line you out, SB is not a certifying agency.

 

[elan]

Sorry if I have not put the question clear, what I was trying to ask is
"out of real experience at what depth does an average Joe start experiencing narcosis"

I think this has nothing to do with certifying agency and certifications etc, that's the nature of how our body behaves. And if I talk to one instructor it's just one person that is much less than a lot of those people on SB who has experience.

I understand that everyone is different and I also understand the fact that rec limit is 130' but I have heard many people saying having narc in a range of 110',

Is there any statistical data is available ?

 

[Sinbad the Diver]

If you are trying to figure out what limit to set to avoid being narced...there is no hard answer. The effects are different between people and between dives. One dive you might feel fine at 120' another day you get freaked at 90'. I went to 110' one morning and was fine. Went to 90' that afternoon and was narced big.

 

[Selachimorpha]

Nitrogen Narcosis varies a lot between individuals. It can also change for one person between different dives, even if the depth is the same.

 

[muddiver]

Sinbad the Diver is correct, there is no definate answer because diving physiology, just like medicine, is not an exact science due to people having different physiological makeups.

One agentcy I trained through reccomends a maximum depth on air of 99 feet (30 m) based on the statistical/theoretical effect of Nitrogen at a partial pressure of 4.0 ATA causing narcotic affects.

Personally I have been to 135 feet (41 m) once and I can't say as I notice any affect. I also dive to the 100 foot to 120 foot (30 m to 37 m) range regularly on air, but I am always staying focused on my gas level, computer display, camera and the mission I have set for myself. Staying focused helps reduce the effect of narcoses but does not prevent it.

 

[Blackwood]

To me, there is a definite correlation between comfort and susceptibility to narcosis.

In particular, if I'm uncomfortable (i.e. cold) I get narced easier (shallower).

Shallowest I can remember recognizing impairment was around 80-90 feet on EAN32. That was in a 7mm wetsuit and I was rather cold.

but I am always staying focused on my gas level, computer display, camera and the mission I have set for myself. Staying focused helps reduce the effect of narcoses but does not prevent it.

There is (for me anyway) a fine line between "focused" and "fixated." As I've remarked before, usually my first indication that I'm narced is a fixation, often on my gauges (and an associated difficulty remembering what they said).

 

[elan]

Sinbad the Diver is correct, there is no definate answer because diving physiology, just like medicine, is not an exact science due to people having different physiological makeups.

One agentcy I trained through reccomends a maximum depth on air of 99 feet (30 m) based on the statistical/theoretical effect of Nitrogen at a partial pressure of 4.0 ATA causing narcotic affects.

That's kind of answer I was looking for.

 

[SailNaked]

I remember a dive that like blackwood said I would look at my gauges and not be able to remember what I saw or why I looked, I think it was at about 70 ft,(I was nervous because I did not have a computer as was not keeping track of my dives, I know better now). and I have a few dives to 110 and no noticeable effect, everything was as it should be and I was relaxed and aware of all about me.

we have not heard from the old school divers that would go to 200 and at what depth they knew they were narced and were dealing with it.

 

[DevonDiver]

Narcosis susceptability varies from person to person and from day to day, and other psychological (i.e. pre-existing nervousness) and physical (cold, exertion) factors have an impact upon this.

Most recreational agencies set a max depth of 5ata (40m) for properly trained and equipped divers. GUE state a maximum narcotic depth of 30m. These limits seem quite reasonable to keep 99% of divers away from debilitating effects of narcosis.

Technical agencies allow diving (on air) down to 45-50m, but this assumes greater familiarity with diving at depth. However, there is an increasing trend for the use or normoxic trimix to reduce the narcotic depth back to the 30-40m range.

From my own personal experience, 40m is a safe and sensible maximum depth for the 'average Joe' - if they are comfortable with the conditions of the dive, in good fitness and capable in the water. It is also important to exercise personal responsibility, a proper risk asssessment and personal awareness to reduce that maximum based on your state of mind, physical condition and water conditions.

I've dived on air to 260ft on several occasions - from those experiences, I firmly believe that it takes considerable experience and mental focus to keep a dive running smoothly and safely. The level of narcosis below 50m rises rapidly every extra meter and can be debilitating.