Jim,

I don't think that the problem is with recreational nitrox.  I think that
the problem is the way that it is taught by the agencies.  I proudly hide my
tdi nitrox shingle and hope no one ever asks to see it.

When I took the course, they said:
-always use a bottom p02 of 1.6 except on unusually cold or strenuous dives
(then use 1.4)
-in this area all dives are cold with current and you are used to it, so
there is no problem always diving p02 of 1.6

This is too stupid.  I didn't realize that at the time (I was 17 yrs old).
That was only a couple problems with the course.  They also encouraged
carrying a bottle of ean39 beyond its MOD for use as a bailout gas.  Where
have we heard this crap before???

Nitrox shouldn't be used to avoid a few minutes of deco, but can be used to
increase safety.  A lot of people diving at altitude dive ean as air to
increase safety on recreational dives.

The problem isn't with an 80 full of nitrox... The problem is how the
industry teaches its use.

ss

-----Original Message-----
From: Jim Cobb [mailto:cobber@ci*.co*]
Sent: October 10, 2000 10:13 PM
To: klind@al*.ne*; dmdalton
Cc: dwiden@ho*.co*; donburke56@ne*.ne*; 'Paul Braunbehrens';
techdiver@aquanaut.com
Subject: Re: rec trimix


Kent-

I guess I was a little obscure. What I am saying is the nitrox presumption
that you can avoid deco for certain profiles by cranking up your PP02 to 1.5
or even 1.6.

So I would not agree with the diver who does your hypothetical dive who,
instead of using air and getting out of the water at 20 mins, mixes a 40
nitrox to stay in for 40 mins. Personally I would prefer do 5 mins of deco
on 02. This limits your overall exposure to to the high PP02's from 40 mins
at 1.44 to 5 mins at 1.6 while at rest. In tech diving reserving your high
PP02 for deco gives you the opportunity to do air breaks and give your lungs
a rest, something you can't do at the bottom.

   Jim
 -------------------------------------------------------------------
 Learn About Trimix at http://www.cisatlantic.com/trimix/

> From: "Kent Lind" <klind@al*.ne*>
> Reply-To: <klind@al*.ne*>
> Date: Tue, 10 Oct 2000 16:37:53 -0800
> To: <cobber@ci*.co*>, "dmdalton" <dmdalton@qu*.ne*>
> Cc: <dwiden@ho*.co*>, <donburke56@ne*.ne*>, "'Paul Braunbehrens'"
> <Bakalite@ba*.co*>, <techdiver@aquanaut.com>
> Subject: RE: rec trimix
> 
> Jim:
> 
> Maybe I'm missing the point of your post.  But I do what you describe all
> the time.  Not the working PP02 over 1.2 but using nitrox to reduce or
> eliminate deco time.
> 
> Here's a hypothetical.  What gas would you use for say a 1 hour cave dive
at
> 85' max depth?  That's a pretty typical profile.  Are you going to use
air,
> trimix, or something simple like nitrox 32 which you can get pumped out of
> banks at the local shop?
> 
> 
> -----Original Message-----
> From: Jim Cobb [mailto:cobber@ci*.co*]
> Sent: Monday, October 09, 2000 10:55 AM
> To: dmdalton
> Cc: dwiden@ho*.co*; donburke56@ne*.ne*; 'Paul Braunbehrens';
> techdiver@aquanaut.com
> Subject: Re: rec trimix
> 
> 
> I know this is going to piss off a lot of rec divers but I believe that
> increasing your bottom PP02's for the purpose of avoiding a deco
obligation
> is a really stupid idea. It is typical of our sport that this principle is
> embraced by almost everybody. Even to the point of calling potentially
> deadly hyperoxic mixes "safeair".
> 
> I think there should be an industry-wide ban of bottom or working PP02's
of
> anything over 1.2. And if you need to spend more time down there then you
> need to do it right with doubles and a deco plan. The idea of "standard"
> trimixes with 02 of 32 or 36 or greater is inverse to common sense.
> 
> Jim
> 
> On Monday, October 9, 2000, at 01:20 AM, dmdalton wrote:
> 
> David, Don & whomever else,
> 
> Why does this need to be a gas that "tracks" air? Anyone who would be
> interested in the minimal extra training necessary for a recreationally
> oriented Trimix would either already be Nitrox trained or certainly
capable
> of it. As was already pointed out a Tri-Ox course could easily make Nitrox
a
> thing of the past. If we are talking about "no stop dives" then wouldn't
it
> make sense to boost the O2 level to get some increased bottom time? A
21X24
> @ 130 ft for 5 minutes calls for 1 min at 30, 20 & 10 (Deco Planner GF -
lo
> 25/hi 90). While a 28 X 35 gives you 10 min @ 130 and only adds 1 min at
40
> ft to the above. Nitrox has it's limits and so would Tri-Ox. I would
venture
> to say that an individual breathing Tri-Ox of 28 X 35 would be far less
> likely to ignore the 130 ft limit than someone breathing EAN 28.
> 
> As for the Rec Agencies, I think they will be the ones to embrace this mix
> which would be one more specialty that they could get into their
curriculum.
> They certainly have all embraced devil gas, I'm sorry, Nitrox. Yeah, I
know
> it took a while but when Tri-Ox hit's for real they will all jump on it
like
> a chicken on a June bug. The gentleman I took Nitrox from ( a former NOAA
> Nitrox Diver of 14 years) was talking about standardized Tri-Ox 32 &
Tri-Ox
> 36, 3 years ago when I took the course.
> 
> I believe the bigger challenge is the few shops that pump Trimix. In the
DC
> area I know of only one shop that pumps it and I understand that they are
> getting in the neighborhood of $80 for a single tank of Trimix.
Outlandish,
> but then I understand that in NY you can get hit up $20 for a single of
> Nitrox.
> 
> Dave Dalton
> 
> 
> ----- Original Message -----
> From: David B. Widen <dwiden@ho*.co*>
> To: <donburke56@ne*.ne*>; 'Paul Braunbehrens' <Bakalite@ba*.co*>;
> <techdiver@aquanaut.com>
> Sent: Sunday, October 08, 2000 2:53 PM
> Subject: RE: rec trimix
> 
> 
>> Don
>> 
>> Good thought. It will be hell to get the rec agency to support.
>> I ran some of the numbers through Deco Planner and some other
> calculations.
>> 
>> To more closely track air and without penalties a 21x24 works with END of
> 80
>> IAW DecoPlanner and END of 90 if you calc with N2 & O2 as narcotic gases.
>> Without building the whole tables w/SIT and repet groups. There are
> several
>> general mixes that would work well. The Normoxic value would serve the
>> uninformed or hard headed person who exceeds 130. It would also support
> and
>> assist in the transistion of new divers to this type of dive gas and
idea.
>> 
>> Type Cost: 21x24 $.215/cuft 21x30 $.252/cuft
>> AL80 21x24 ~$17 21x30 ~$20
>> ST95 21x24 ~$21 21x30 ~$24
>> 
>> Cost increase 3 to 5 times without over fills.
>> 
>> David
>> 
>>> -----Original Message-----
>>> From: Don Burke [mailto:donburke56@ya*.co*]
>>> Sent: Sunday, October 08, 2000 7:56 AM
>>> To: Paul Braunbehrens; techdiver@aquanaut.com
>>> Subject: Re:rec trimix
>>> 
>>> 
>>> Comments scattered within
>>> 
>>> --- Paul Braunbehrens <Bakalite@ba*.co*> wrote:
>>>> I think that this is where trimix computers come in.
>>>> Even if it's a
>>>> good "drop in" gas, I'd still like to track what I'm
>>>> really using.
>>> 
>>> Certainly. It isn't rocket science in any case. I
>>> haven't worked out _every_ possibility so the He
>>> content may have to be backed off a couple of points
>>> to stay inside the air tables.
>>> 
>>> A set of rec-tri tables wouldn't seem to be too hard
>>> to make up for repetitive diving, although PADI would
>>> probably have to actually come up with a new set of
>>> surface interval numbers to allow for He instead of
>>> the Xerox solution used for the surface intervals on
>>> the PADI EAN tables.
>>> 
>>> 
>>>> Also, because of O2 Tox there would have to be some
>>>> kind of an
>>>> "orientation class" at the least. If you go down to
>>>> 160 on air and
>>>> come back up right away you're stupid, but you won't
>>>> tox on O2. A
>>>> "drop in" gas would need some serious warning if it
>>>> has a higher O2
>>>> content.
>>> 
>>> Yeah, the orientation would be:
>>> 
>>> "Remember when I told you to stay shallower than 130?
>>> Well this time I mean it."
>>> 
>>> You didn't mention the CNS clock, but since we are on
>>> the subject of O2, I haven't figured out a way to run
>>> out the clock with 28% O2 without going well into deco
>>> stop diving or going below 130. I doubt there is one.
>>> 
>>>> Don Burke wrote:
>>>> ~
>>>>> As variation on the same theme, how about 28/35 as
>>>> a "drop-in" replacement for air?
>>>>> 
>>>>> It is good to 130 feet under any conditions a rec
>>>> diver will see.
>>>>> 
>>>>> The no stop times are longer than for air.
>>>>> 
>>>>> The END at 130 feet is about 80 feet.
>>>>> 
>>>>> The only downside is cost.
>>>>> 
>>>>> Don Burke
>>>>> Chesapeake, Virginia
>>>>> 
>> 
>> --
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