Bill, to make matters worse, Mouth is telling this guy to use the 80% at
30 feet due to the higher po2. Well he just told us it was "safer" at 20
due to the lower po2? What gives? The fact is the while the 30 foot stop
shortens a tad, the oxygen window at 20, 15, 10 or any other depth on 80
is pitiful and amounts to wasting your time.

As you point out, if the deco is done correctly below this level, the
rest is merely effective management of the o2 window with the increased
gradient for speedy egress.

Mouth has gone to great lengths to do anything that is other than what
the most successful project in diving has learned. He just can't stand
the fact that we are the leaders in this kind of diving and he is not.

Also, the what they are doing with the fill pressures is actually to use
STEEL low prssure stages and then fill them to 3000 area, or whatever
they can to give them their 80%. The original genesis of Mouth's 80/20
stupidity was to get more gas for his hooves and to keep them from
toxing while bobbing and weaving at deco.


Bill Mee wrote:
> 
> >>When I have doplered EAN 50 we get significant bubbles, while we do use
> EAN
> >>50 in advanced eANx we prefer teh 80 for technical programs it is cleaner
> >>fro a bubble standpoint
> >>
> 
> Tom,
> 
> The use EANX 50 by itself has nothing to do with bubbles. The question is
> what were you doing before you got to the EANX 50 gas change? Like what
> gases were you breathing and what were your actual bottom times?
> 
> It is well known that the latter phase of the decompression is essentially
> worthless if you have not performed the deeper stops correctly, have not
> breathed the right gases for the correct times etc., etc., etc.  and all you
> are really doing is treating the symptoms.
> 
> We all know that you are trying to justify the use of 80/20 at the expense
> of doing the right right thing.  The original reason for using the 80/20 was
> to get more cubic feet of gas in the smaller 30 and 40  cf cylinders because
> you are running them up to 3500 psi instead of the pressure from the
> commercially supplied oxygen bottles.  May I call your attention to the
> original Baker's Dozen reasons for not using 80/20.
> 
> >>
> >>When I have doplered EAN 50 we get significant bubbles, while we do use
> EAN
> >>50 in advanced eANx we prefer teh 80 for technical programs it is cleaner
> >>fro a bubble standpoint
> >>
> 
> >>EAN 50 still provided significantly longer deco schedules and if you
> >doppler
> >>the diver you get more bubbles on longer dives.
> 
> What ? You have got to be kidding me. You mean we have been doing the wrong
> way all these years in the WKPP?
> Thanks for tellings us belatedly.
> 
> >>
> >>I have had great success in the use of EAN 80 and EAN 70 on normoxic mix.
> I
> >>do not know of any bends following these schedules nor any tox incidents.
> 
> >>There are several tox incidents on o2 at 6 m which was the original reason
> >>we went to eAN 80
> 
> Sure and several people who have been killed crossing the street were
> wearing red shirts on  Friday the 13th.   I always wear blue shirts to
> prevent this.
> 
> >>
> >>Respectfully yours,
> >>Tom Mount
> >>CEO IANTD World HQ
> >>http://www.iantd.com
> >>
> 
> Originally posted by George, 9/18/97:
> 
> -----------
> A (BAKER'S) DOZEN REASONS  WHY WE DO NOT USE 80/20
> 
> 1) This gas was introduced in an effort to overcome the inability of
> unqualified student "tech" divers to control their buoyancy in open
> water, and is as such is yet one more concession to doing things in a
> convoluted fashion to offset a self- inflicted set of problems brought
> on by the "doing it wrong" thinking that pervades diving today.
> 
> 2) A heavy sea is not a problem for a deco stop if it is not posing a
> lung-loading problem. Look at your depth guage in a heavy sea and "see"
> for yourself what the changes are - insignificant, and if they are not,
> you should either not have been diving or incurring a decompression
> liability of this magnitude in the first place. In the event of a change
> in conditions during the dive, see below where the 80/20 becomes a
> liability rather than an assett.
> 
>  3) In the interest of using a standardized set of gases for which you
> can permanently mark your bottles , it is a poor concession to inability
> to sacrifice the benfits of pure  O2 to accomodate a real or percived
> lack of skill - learn to dive before taking up techdiving.
> 
>  4) In this same interest you will find that when you graduate to real
> diving, as in caves,  you will not want to accellerate your ppo2 at
> lower depths while still being faced with a long decompression at
> shallower depths, and making bizarre mixes  to do this is a dangerous
> mistake (just like the fantasy of holding an accellerated ppo2 on a
> rebreather throughout a deco). I am anticipating the thinking that the
> 80/20  crowd would then go to an additional oxygen in cave without
> accounting for total exposure, and subject themselves to the risk of tox
> in the final deco steps. Tox you do not get out of - bends you do.
> 
>  5) The 80/20 mix is in fact totally useless and contraindicated as a
> deco gas. At thirty  feet  it is only a 1.52 ppo2 ( the real 1.6 ppo2
> gas would be 84/16) and as such  does not either   provide the right
> oxygen window, nor does it does it work as well as pure oxygen without
> an inert gas at any depth. The gas mixing in your lungs has already
> lowerd the effective ppo2 enough to prevent spiking at 20 feet anyway
> with the use of pure oxygen - in other words, we aer dealing with a
> simplisitc misunderstanding here, or "old wives tale" that is typical in
> diving.
> 
>  6) If 100% oxygen is a percieved buoyancy control risk at 20 feet, then
> why is the  same ppo2  ( intended) not a risk at 30 feet? This shows the
> total lack of reasonable logic involved in the decision to use this gas,
> as well as a lack of understanding of the whole picture ( see the rest
> of this discussion).
> 
>  7) Along those lines, all we hear is howling about "oxygen cleaning"
> above 40% mixtures,  and dive shop proprietors on here complaining about
> scuba tanks with oxygen in them  being filled in their shops. With a
> pure oxygen system, the tank only ever gets filled with  oxygen from
> oxygen tanks, not from every dive shop compressor it sees. Again , this
> shows  the total inconsistency of agency thinking, and reveals that the
> true reason for this gas   is to pretend to lower liability for teaching
> incompetents to dive, which is bull, and to attempt to accrue some
> inventive accomplishemts to the dive agency pundits who themseleves
> prove  that they do no real diving by making this recommendation
> in the first place. This is like the  colored regs, the stages on either
> side, the quick-release buckle, and the poodle jacket: nonsense of the
> most obvious nature developped through one-dimesional thinking by those
> whose universe of understanding is not only severly limited, but blinded
> by the hubris of not being the "inventor" of the techniques that work.
> 
>  8) Any perceived decompression benefit of using a higher ppo2 at 30
> feet with 80/20  is then given back  by the lowered ppo2 at 20 feet, not
> to mention the fact that the presence of the inert gas in the  breathing
> mixture defeats the purpose of using  oxygen in the first place ( see
> the Physiology and  Medicine of Diving) .   The ppo2 of 80/20 at 20 feet
> is 1.28, not much of an oxygen window, and at 10 feet it is 1.04 -
> useless for deco. To make matters worse, you can not get  out from your
> 30 foot stop in an emergency ( not doing the other stops)  on  the 80/20
> mix without really risking a type 2 hit.
> 
>  9)  This is a dangerous method to achieve a greater total volume of gas
> for the bad breathers (another obvious reason the gas is in vogue), who
> should not be incurring these decos, and even that benefit of having
> more gas is lost since it is breathed at 30 feet, and then has to last
> for the other stops. The fact is that gas is effecively saved by using
> the lower deco  gas up to this point, relying on the pressure gradient
> to both achieve the deco and provide a break from high the previous
> gas's higher PPO2 prior to going to pure oxygen  where the spike could
> be a problem on an extreme exposure without an adequate low ppo2 break (
> again this shows that the 80% user is a neopyte diver with no real
> experience or   understanding of the true risks of these dives) .
> 
> 10) The 20-30% longer 30 foot time on the lower ppo2 is not only
> overcome on the pure oxygen at the next stops,  the breaks do not come
> into play until the initial good dose of pure oxygen has been absorbed,
> since you are not spiking from a  high pervious dose without a break
> that is effectively achieved on the previous gas. These things need to
> be understood and taught by the agencies, not some superficial
> convolution that is designed to obfuscate the problem rather than
> openly acknowledge and deal with it in a responsible fashion.
> 
> 11) In an emergency situation, getting onto the pure O2 for 20 minutes
> or so (for long dives something approximating the bottom time or a any
> decent  interval)  would  give you a real good shot at getting out of
> the water having missed the rest of  your deco and living through it
> with pain hits only. You have to think these things all the way though,
> not go for the transparent superficial thinking of those who merely are
> trying to "make their mark" with some "great" idea they can call their
> own. The acid test is , as always, is the caliber of the divers who
> adopt these practices.
> 
>  12) If there is some problem with your deco or you otherwise develop
> symptoms and need oxygen either on the surface or back in the water, it
> is silly to have not had it there all along. 80/20 is a joke for that
> purpose, unless you have asthma, in which case any accellerated oxygen
> mix would be a nightmare. This is again part of the "thinking it all the
> way through" phiosophy which is obviously mising from the 80/20
> argument.
> 
>  13)  Only a card-carrying stroke would do somethng like this, and
> showing up with 80/20 is no different than wearing a sign on your back
> saying "I am a stroke, and have the papers to prove it". It announces to
> all the world that you have no clue, kind of like wearing clip-on
> suspenders or having dog dirt on your shoes.
> 
>   George Irvine
>   Director, WKPP
>   "Do It Right" (or don't do it at all)
> --
> ...
> 
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