200' on air for 5 min bottom time?

[Ste Wart]

Deep air will always be around as a way of diving as will Cave, Wreck, Ocean, and Lake divers.

Amen to that

. So far I've been lucky with deep air and having no trimix training, but deco gases have sure made my dives much easier to stand.

You know how big of a contradiction this whole thread is?
Yes, I agree that your physiology may have contributed and your attitude definetly did, but ruling out the breathing gas is pretty damn nonchalant. Its like saying my fringed nerves after the binge drinking was caused by not remembering what I did and not the alcohol..
Then you go on and say you make a good plan and follow that plan. Then why the hell did you put yourself in a position where you nearly freak out in the first place? That does NOT sound like good planning, although the recovery was obviously good given youre still here.

Tigerman, your profile states that you are AOW. Do you really think this is the correct thread to be posting in and advising others on 'deep air' diving? If you have some actual experience of deep air diving then feel free to contribute. Otherwise Jared's comments were about as real as deep air gets. Sometimes its good, sometimes it's not so good, sometimes it kills you. Pretty much like all other forms of diving.

 

[Kevrumbo]

Wayne -- Thank you.

Now, what about "un-adaptation" -- does it occur too or is it "like riding a bicycle" -- once learned (experienced), forever there?

Peter "un-adaptation" occurs, however not in the same way as adaptation. It is like riding a bicycle in some ways. If someone hasn't ridden in a couple of years, they will likely still be able to ride, but not as well as they once did. I believe that the adaptation process is primarily mental attitude/state-of-mind. There are physical properties such as cold, exertion, etc., that affect narcosis, yet we believe that non-physical factors like light also have an affect. If everything was physical, it would be more likely that a person would react in a similar way under repeated exposures. We know that this is not the case, as the same person can react differently to narcosis at different times. This isn't scientifically understood, so I can only speak to the reaction and not the cause.
. . .<snip>

On adaptation to Deep Air and Nitrogen Narcosis:

"Moreover, our results suggest that experienced divers can discriminate between the behavioral and subjective components of narcosis. . .It has been proposed that the intensity of narcotic symptoms could be used by divers to gauge the extent of performance loss (10). The present results indicate that this advice is inappropriate for adapted divers because the two components of narcosis [behavioral and subjective] uncouple in a direction that could lead to an overestimation of performance capabilities --a potentially dangerous situation. On the other hand, the question arises as to whether adaptation confers any benefits on the diver, since performance efficiency is not directly improved and could be overestimated. In this regard, it could be argued that a reduction in symptom intensity reduces the possibility that attention will be focused on subjective sensations rather than the task at hand." [i.e. Subjective, sensations awareness vs. Situational, objective task-at-hand awareness??]
From:
p.9, Hamilton K, Laliberté MF, Fowler B. Dissociation of the behavioral and
subjective components of nitrogen narcosis and diver adaptation. Undersea Hyperb
Med. 1995 Mar;22(1):41-9. PubMed PMID: 7742709.

​

 

[Slamfire]

Ratio Deco Method had the hard stops begin at 100'/30m, linearly for one minute every 10'/3m to 20'/6m, and then a slow 3fpm/1mpm ascent to the surface. (Slightly different deco profile shaping) see link back:

http://www.scubaboard.com/forums/advanced-scuba-discussions/455535-200-air-5-min-bottom-time-4.html#post6759370

For ratio deco, the determination of your first hard stop is based only on maximum depth, right? In other words time at that max depth is not considered when determining that first stop, is it?

This is a fairly short bottom time. Hence why it looks like the deco obligation is not that big of a deal. The message I wanted to convey was that at these depths, you don't have much margin for deviating from your original plan. Just plain staying 3 minutes longer increases your ceiling from 60' to 80'. Increase in deco obligation with the consequent increase in required gas is another vital issue to consider.

In short, you don't have a margin for error or to be complacent about your situational awareness. And saying that your mind was too fogged by narcosis to be totally disciplined in the execution of your plan will not change the reality that you will still have to pay for that lack of discipline. Hopefully the price won't be too high.

 

[Tigerman]

...
Tigerman, your profile states that you are AOW. Do you really think this is the correct thread to be posting in and advising others on 'deep air' diving? If you have some actual experience of deep air diving then feel free to contribute. Otherwise Jared's comments were about as real as deep air gets. Sometimes its good, sometimes it's not so good, sometimes it kills you. Pretty much like all other forms of diving.

I see now that theres a typo in the post I made that you quoted, it should be "post" instead of thread"..
That said. I didnt know you needed a rocket science degree to see that saying the gas and being narced is related and that its a contradiction saying you put yourself in a dangerous position and saying you always make a good plan..

 

[flots am]

Thanks for calling me a Debbie downer. Whomever, ya you right I just don't like people dying or killing someone else with an avoidable plan.
There are agencies that train deep air, etc... Go to them
I also ran the plan with an al80 as the tank and a "normal" newbie ish SAC rate of .75ish and guess what .... Empty tank at surface with the plan originally proposed.

You must be a hoover.

I ran the plan and had 150PSI left.

flots.

 

[oldschoolto]

You must be a hoover.

I ran the plan and had 150PSI left.

flots.

Any diver can go from having a very good air consumption to " HOOVER " in short order.....

Jim...

 

[flots am]

Any diver can go from having a very good air consumption to " HOOVER " in short order.....

Jim...

I think you missed the ""

 

[drbill]

As for adaptation, the following is based strictly on my own personal experience and should not be extrapolated to anyone else.

As I've stated, I dove deep (160-200 fsw) on air for a fairly extended period of time when I was filming for an episode of my show on "'Deep' Ecology." Since I would only do this solo (not wishing to risk another diver's safety), I was very conscious of any changes in my perception. By slowly increasing my depth over a period of about two months, I was able to do many dives to these depths without appreciable narcosis (yes, as judged subjectively). I remember one day I averaged 180 fsw on three dives (200. 180 and 160 respectively).When I no longer needed to continue this filming, I returned to shallow depths (preferring bottom/filming time over depth). On my next dive to any appreciable depth (151 fsw on the wreck of the Infidel) months later, I was as narced as I've ever been in my life. I even got noticeably narced at 107 fsw a while later.

It is my opinion based on my experience that any adaptation to elevated nitrogen levels only remains as long as a diver continues to undertake "frequent" deep dives on air. I cannot say this is scientifically proven, nor that it applies to everyone.

 

[oldschoolto]

Sorry.......:blinking:

Jim...

 

[Kevrumbo]

For ratio deco, the determination of your first hard stop is based only on maximum depth, right? In other words time at that max depth is not considered when determining that first stop, is it?

This is a fairly short bottom time. Hence why it looks like the deco obligation is not that big of a deal. The message I wanted to convey was that at these depths, you don't have much margin for deviating from your original plan. Just plain staying 3 minutes longer increases your ceiling from 60' to 80'. Increase in deco obligation with the consequent increase in required gas is another vital issue to consider.

In short, you don't have a margin for error or to be complacent about your situational awareness. And saying that your mind was too fogged by narcosis to be totally disciplined in the execution of your plan will not change the reality that you will still have to pay for that lack of discipline. Hopefully the price won't be too high.

In general, time and depth are determining factors of your first deep stop in Ratio Deco; this hypothetical dive to 200'/60m for 5 minutes is special case -more like a quick abort of an attempted tech dive (like a mis-drop on a wreck which turned out not to be there; This happened to me at 150'/45m trying to find the F4 Phantom Jet outside Subic Bay)- so you simply come up to half your max depth and do 30 second stops & 30 second moves every decade depth (triad depth in meters) to 20'/6m, and then an optional 3fpm/1mpm slow ascent to surface, all on backgas.