----- Original Message -----
From: "Carl" <[log in to unmask]>


> Mike,
>
> > > I understand things from Draeger's literature and through speaking
with
> > > their representatives and Dolphin users, there are still a few
negatives.
> >
> > There are negatives with EVERY rebreather out there.
>
> Ok, give me the negatives that are life threatening on the Halcyon.

It's a rebreather.

Seriously, I don't know what they are. I have not spent a lot of time
studying the Halcyon because it's not likely that I'll win the lottery and
be able to afford one anytime in the very near future. I have no doubt that
it is considerably safer to dive than the Dolphin, but I also have no doubt
that there are ways to kill yourself just as dead with one.


>
> > > First, you are betting your life on your O2 analyzer, not just on just
the
> > > oxygen toxicity side, but also, as Carl pointed out, on the hypoxia
side.
> > > The more stress you are under or the more vigorously you move the
lower
> > the
> > > PO2 and consequently the oxygen available to your brain.
> >
> > You are betting your life on your O2 analyzer for any gas dive, be it
open
> > or closed circuit.
>
> What?!  If I do an OC gas dive the O2 analyzer is *NOT* used in a life
> support manner.

It most certainly is if you analyze your gas prior to your dive, and I know
that you do that. You are betting your life on that analyser and the O2 cell
in it.


>I *mix* the gas and I already *KNOW* what percentage
> the O2 is.

You *KNOW* what % it is if you didn't fuck up the blend.


> That O2 analyzer is only used to *confirm* what I already
> know.

Again betting your life on the fact that you didn't fuck up the mix and that
the analyser is correct.


>
> In some CCRs the O2 measuring system is used to determine how to mix the
> gas FOR you or provides you with information that YOU must use to mix
> the gas manually.  This is information that that you have NO WAY to
> confirm independantly.  Systems like the Dolphin are only *SINGLE*
> measurement systems.  From that perspective at least other units
> (like the Cis Lunar) have a triple redundant measurement system.

Yep.


>
> Plus, if one of the O2 measurement cells "sticks" (which must be
> detected
> by the user!) there are methods of "clearing" that stick such as blowing
> diluent across them (I believe this method is available on the CL).
> No such "manual" method of clearing a stuck device exists on the
> Dolphin.

Yep...


>
> > I have a bail out system that I use so drive bottle  size does not
matter...
>
> But you have to *realize* that there's a failure.  That realization is
> NOT
> guaranteed, however, I bet dollars to donuts you WOULD recognize a
> continuous
> shortening of breatheable air (which is how the Halcyon reacts to an
> out of gas situation).

Yep.


>
> > Wrong. The Dolphin  has three orifices for gas.
>
> 3 orifices!  That's even better for the kinky people out there :^)

Why you think I like it?  :-)


>
> > Have not heard a noisy belch yet. Unit does release bubbles, but it is
not
> > particularly noisy, much less so than open circuit and a smaller amount
of
> > bubbles also.
>
> It's not as noisy as OC but it is definitely still there, however, once
> you become "complacent" you tend not to hear it anymore.  I found that
> happening as soon as my 2nd dive on the thing.

I won't argue that. OC bubbles don't bother me anymore either.


>
> > Don't know about your experience with it, but I find that I am able to
get
> > much closer to the fishies with the Dolphin vs Open circuit...
>
> I don't doubt that you can get *closer* but it's still not optimum.

Never said it was.


> Now,
> pretend you're at 66'.  With a Halcyon not ony would you have the
> reduced
> gas due to recirculation but that volume would be further cut down by
> a factor of roughly 3 at that depth.

It's a damn nice unit. No arguement.


>
> > Ditto with every other breather out there...
>
> Yep, most serious rebreather divers take along bottles of O2 and He with
> them, or, have them shipped ahead of time.  This isn't a "cheap" way of
> diving.

Duh... :-)


>
> > >         Of course, because of the counter lung, it is much more
difficult
> > to
> > > control one's depth and consequently to approach fish smoothly and
> > > naturally.
> >
> > Excuse me? I found that after 4 or 5 dives on the unit, buoyancy control
was
> > a non issue.
>
> I agree entirely here.  The RB only amplifies bad bouyancy.

Yep..


>
> > > Moreover,
> > > because of the insidious nature of hypoxia and the structure of
Draeger's
> > > technology, I believe Carl's insistence on an Oxygauge is well
founded.
> >
> > I agree that it's well founded also. I don't agree that it's a toy or
should
> > only be dived in ones bathtub.
>
> Ok, I'll add the shower in too and the shallow end of the pool.

You da man. I knew I'd get you to cave and admit that it some use other than
the tub..... :-)

Mike


>
> Carl
>