In a nutshell:

Its a cheap, easy way to make a shit dive gas that does nothing really well.

Its basis for existence is compromise.

Scott


----- Original Message -----
From: "Sidney Brock Frederickson" <Bfrede1615@em*.ms*.co*>
To: <ScottBonis@ao*.co*>; <RDecker388@ao*.co*>; <mhkane@pr*.ne*>
Cc: <techdiver@aquanaut.com>
Sent: Saturday, August 05, 2000 7:10 AM
Subject: Re: Heli-air


> Scott:
>     Yesterday after reading parts of the extensive catfight on rec.scuba
> over recreational tri mix,
> I emailed the OTHER Scott at Hoodsports, esssentially asking who, what,
> when, where, and how.
> Scott replied he would contact a local blender and see if he could arrange
a
> try-dive for me.
> I'm fortunate in that I'm actively mentored by a commercial diver with a
lot
> of mixed gas experience, but, all the same last night we were throwing
about
> various conditions and scenarios, including forced deco, bail out, extreme
> cold (argon vs back gas for suits) emergency bounce dives past MOD, stage
> bottles, travel mix, etc. In other words all those nasty real world things
> that can screw up nice day.
>     Mentor Mikes experience has been with surface supplied heliair as
taught
> by Ocean Corp., who stressed the use of a travel mix even then, reserving
> Hypoxic mixes for true saturation diving. The use of any trimix with out a
> travel mix struck him as unusual, so if and when this try dive comes
along,
> he'll be there asking all those "how come" questions.
>     My point being - Ok Heliair, hotX, Normoxic trimix, Hotmix sounds like
a
> good thing. I narc easily so Nitrox is good,as I explained to Scott, being
> able to keep that clear head past 110 would be better. Heliair seems ideal
> for that purpose, with the understanding of possible longer deco, extra
> bottles, etc.
> But as you have noted there seems to be some arbitrary bottoming out on
> depth limits. Ive heard MODs of 150, 180, 200, 230 fsw. Also alot of
ranting
> about various agencies forcing useless jumping thru hoops on what should
be
> a simple learning curve ( that I agree with- I still can't make heads or
> tails of IANTD or TDI's "progression' other than charging a lot of money).
> Maybe I'm just spoiled by having answers a phone call away.Our conclusion
> was IF heliar is the best of all possible worlds for MOST diving, IF it
can
> be used on more extreme depths- then why not as an all purpose back gas?
>
>     Just looking to learn. We've some excellent diving here in the 100 to
> 250 ft range, and I'd like to take advantage of it.
>
>     Dive Safe
>     Brock
>
> ----- Original Message -----
> From: <ScottBonis@ao*.co*>
> To: <RDecker388@ao*.co*>; <mhkane@pr*.ne*>; <techdiver@aquanaut.com>
> Sent: Friday, August 04, 2000 12:50 PM
> Subject: Heli-air
>
>
> > Hi Mike and Bob,
> >
> > On the Scuba Chat on AOL last evening, we had just started to talk about
> the
> > concept of using the heli-air trimix blends as possible bottom mixes
> instead
> > of other blends of trimix, when time ran out.  Now previously you had
> > written...
> >
> >  RDecker388@ao*.co* or mhkane@pr*.ne* (I'm not sure which) wrote:
> >
> > << I often have these discussions, and generally what I do is focus
on a
> few
> > simple concepts.  In that I suggest that at least we [DIR] are
presenting
> > something.  Many seem to want to just argue the anti- *anything*
approach.
> > I always suggest let's go line by line.  What do you believe in your
> system
> > is better than what we believe in the DIR system and why???  I have
> little,
> > if any, tolerance for someone who just wants to argue for the sake of
> > agrguing.  If you have a position, put it forward and let's discuss the
> > merits. >>
> >
> > I am not arguing against anything.  I have learned a great deal from
> studying
> > about, analyzing and adopting various DIR techniques.  I would like to
> > understand why the apparent objection to using heli-air.
> >
> > I see one important (to me extremely significant) advantage for heli-air
> and
> > one other nice feature.  The significant advantage is that at any time,
I
> can
> > use an oxygen sensor and determine exactly what is in my tanks.  This is
> not
> > true with other trimix blends.  And the nice feature is that because I
can
> > analyze my blend, I can have confidence in topping off my half filled
> tanks
> > after each dive, with Helium and then air to optimize the mix for my
next
> > dive.
> >
> > In both of these cases I am not dependent on the accuracy of any
> compressor
> > pressure gauges or the conscientiousness of fill station operators or
any
> > other personnel, in determining exactly what I will be breathing.  And
> when I
> > need a bunch of tanks for a dive team, this becomes IMHO, particularly
> > important.  I teach my students that it is real risky to dive using any
> tank
> > (nitrox or trimix) that they haven't personally analyzed with an
> instrument
> > that they have personally calibrated.
> >
> > As far as the use of heli-air as a bottom mix is concerned, I don't
> > understand the objections.  It's just like other trimix blends but with
a
> > somewhat lower oxygen content.  I pick an acceptable END and that then
> > defines the mix.  Typically the PP(O2) comes out to a little below 1 ATA
> at
> > depth and remembering that we are talking here about bottom mixes and
not
> > deco mixes, a slightly lower PP(O2) would not necessarily seem to be
such
> a
> > bad thing.  And of course for any mix for a dive of less than say, 400
> feet,
> > once I am down to 20 or 30 feet, the mix is no longer hypoxic, so I
don't
> > "need" a travel mix.
> >
> > So could you please explain, in slow and simple terms, what problems are
> > being created?  Have I missed something?  Since I obviously would have
> deco
> > gasses available for any required surface swimming, why is 18/50/32 so
> much
> > better of a mix than 10/50/40 for a say, 250 foot dive?
> >
> > I'm not trying to start any kind of argument here, but I would like to
> > understand the rationale for precluding the use of these heli-air mixes.
> I
> > have attempted to explain "What do you believe in your system is better
> than
> > what we believe in the DIR system and why???"  Although I would not use
> the
> > word "better" but rather "different."
> >
> > I understand that this subject has been discussed previously on this
list,
> > but I have not been able to find the answers to my questions.  The
> previous
> > discussions seems to concentrate on Richard Pyle and Sheck Exley using
> > heli-air, calling heli-air "poor man's trimix" (which as an aside, I had
> > thought only referred specifically to the 17/17 blend obtained from
> putting
> > 500 psi of Helium in an Al 80 tank), saying that oxygen should be
> available
> > for mixing, and arguing that if you can mix heli-air then you should be
> able
> > to mix trimix.  But I cannot find any discussion of why heli-air should
> not
> > be used.
> >
> > Thank you very much for your time in answering my question.
> >
> > Take care and safe diving,      Scott
> >
> > --
> > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
> > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
>
>
>
> --
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