I suggest you consider some independent study on the subject.  Most divers
do their first deco dives unintentionally, by overstaying their no deco time
or by exceeding their planned depth.  It's kind of nice to know what to do
if that happens to you.  It's not exactly rocket science.

Lee

Do the dive on air and do it for 35 minutes instead of the NDL of 25
minutes... It'll then be a deco dive... The question was how much deco time
are you going to be hit with and at what depths... Or in other words, how
much did that extra 10 minutes really cost you... Now, if you can do
something useful during that deco (e.g. drift along a decreasing depth reef,
read a book, or whatever), maybe it makes for a longer useful dive... All in
all, hanging on an anchor line with nothing to do / read gets boring...

the last I read there is no physiological effect of Enriched Air.  There
may however be a psychological one.

The way I read this, you said for EAN36 . . .you should conservately stay
BELOW 100ft.  Ergo, the rest of your sentences seemed to read oddly, if you
consider the "context".

Yes - you wrote stay below 100 ft when you mean stay above 100'  I knew
what you meant

Cool.  Internet site available?  I'm on my way to Arkansas this morning.
This might make interesting reading in the hotel.

Lee

Narcosis is subjective and even with Nitrogen, it's actual mechanism
for manifestation is UNKNOWN. A couple of medical doctors concluding that
O2 is not good for anesthesia doesn't mean sh.t for narcosis or it's
effects on divers.

Whether or not O2 is narcotic is irrelevant. What *IS* important is whether
Nitrox is less narcotic than Air. The plain truth is that the Nitrogen
necessary to induce narcosis MAY BE far below the amounts present in the
richest of recreational nitrox mixes.

BTW, it *remains* a "hypothesis". A hypothesis that remains a hypothesis
after 85 years, is MORE suspect, not LESS.

The *fact* is, that neither I nor my wife, can detect any reduced level
of narcosis using nitrox vs. AIR. Neither can ANYONE ELSE. It is subjective
and there is no possibility of making a concrete determination.

The *fact* is, that the WORST narcosis in my experience was in just 80 feet
breathing EAN36. This, while having significant experience over 100 feet and
as deep as 160-170 with no difficulties.

It is just plain silly for anyone, anywhere to presume that Nitrox is
less narcotic than air.

First, there is no value to the conclusion, unless you plan to attempt a
dive on Nitrox that you would not attempt on air due to narcosis effects.

Second, the presumption that Nitrox is just as narcotic as air costs
*NOTHING*, and has the benefit of preventing you from attempting anything
as stupid as the first objection.

safe diving,

bullshark

A couple of notes:

You are not "recompressed to a PPO2 of 2.8".

If and only if you are subjected to a table 6 (generally for type II),
then you will be recompressed in AIR, to a depth/pressure of 60fswg/26.72 PSIG,
where you will breathe O2 from a mask with a resultant PO2 of ~2.8.

This may seem nitpicky, but it is not. It's like saying a plane ascends
to a PO2 of 0.043. The PO2 in the chamber at the T-6 initial compression,
is 0.59. Were it a table 6A then everything it's all different (165 fswg).

Two: To the best of my knowledge, there are no attempts made in the
course of "tens of thousands" of hyperbaric treatments to assess the
mental acuity of the patient before, during, or after the treatment
beyond conscious/not and comfortable/not. Inside tenders do not breathe
O2 on standard T-6, so nothing is gained by their examination in this respect,
though AFAIK nothing is done, and inside tenders are presumed impaired
(One of the reasons internal tenders do not operate the machinery).

Narcosis at 60 fswg (2.82 ata), though present and detectable, is not
severe, even in air. Obvious/severe narcosis which is easily detectable
at 100+ fswg (4+ ata) is a little hard to test on O2. Even the most sadistic of
researchers is not likely to ask subjects to perform/complete mental acuity
and dexterity tests in pure O2 at 4 or 5 ata. It's not likely that the
subject would complete the exam and repeat assessments would not be likely
either; at least not voluntarily.

Nitrogen narcosis requires Nitrogen of course. The absence of nitrogen in
breathing gas does not dismiss all nitrogen from the body, and not all
nitrogen in solution is removed when passed by the lungs.

Breathing pure O2, it would take about 5 days to remove all the N2 in
your body. Leaving the surface and becoming compressed, you have significant
amounts of Nitrogen in circulation that will remain that way regardless
of what you are breathing.

There is no body of proof anywhere that I know of that will substantiate
any claim to reduced narcosis using Nitrox.

Since Paul Bert noticed it all those years ago, no one has yet defined
the physiological etiology of inert gas narcosis. All the hypothetical
crap is just that.

I don't really care whether O2 is narcotic or not. What I do care about is
that in my experience there is no reduction in narcosis using Nitrox vs. Air.

Personally, I believe the reason for this is that the reduction of available
N2 using recreational mixes is probably insignificant with respect to the
amount of N2 necessary for narcosis to instantiate. Using the richest mix,
the N2 reduction is, after all, only 24%. If you can't accurately measure
narcosis in the first place, how can you measure 3/4 narcosis? Using EAN32
(likely in depths where narcosis is markedly evident in everyone) the advantage
is 14%...can anyone here really claim to be only 86% narc'd or able to observe
14% less narcosis?

Nitrox divers are just as narc'd as air divers. The narcosis event itself
is highly subjective. You've been narc'd lots of times at a certain depth.
According to you, only once(or so) was it "dark". My worst narc ever, was
at a piddling 80 feet breathing EAN36, not breathing air at 150...

I think the discussion of O2 narcotic potential is moot and not really
relevant to whether or not Nitrox is less narcotic.

safe diving,

bullshark

We find you amusing too! Although a bit naive.

   Fair enough, thank you.

   Surely you are aware of the trait of doctors, engineers and the like who
because they have extensive knowledge in a specific area, they believe they
are experts on everything they do.

Curtis