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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