Quinn,

Here I go, responding to something that was said on scuba-l because the
topic is worth discussing...  The original question was about a doubles
setup.  Ron followed up with some dangerous, misleading, and wrong
advise so, after much thought, I decided to followup here on scuba-se.

I normally do not respond to anything on scuba-l but since I KNOW you're
also on scuba-se, well, you would have been far better off asking it
there as all the technically savy people have moved over.  Ron (Fuller)
is *NOT* one of these people even though he speaks brave words.

> At 10:59 AM 7/3/00 -0400, Quinn wrote:
> >Anyone on the list diving doubles? I'm looking for recommendations and
> >advice for what type and brand of manifold to plan for. What
> >recommendations for tanks?

It depends on the application.  For open water ocean work, use double
80's.  For cave diving, double low pressure steel tanks of size
typically
either 95 or 104 cu ft each.  The 120's are typically too large for most
people to be comfortable with and shouldn't be necessary anyway.

The combination of twin lp steel tanks and a wet suit is what
contributed
at least partially to a triple drowning a while back in Florida.  If you
are extremely negative you must have redundant bouyancy - and that does
NOT
mean bungee wings with 2 bladders - that means a dry suit.  In the ocean
it's a good idea to also carry a lift bag.  It can be used as a marker
as well and many other things as well.

The manifold - well, there's *plenty* of information out there on
manifolds - take a look at the gue web site www.gue.com and/or wkpp.org
...

I believe that Halcyon now makes a manifold.  The Dive Rite manifold
of a few years ago was very good (not sure about the current one).
Replace any plastic knobs with rubber ones (the rubber won't crack and
break on impact).

> >The rig would be used prinmarily for wreck and archeological diving, but
> >some cave also.  I am not planning any extreme exploration in the near
> >future.
> >
> >Thanks,
> >
> >Quinn
> Sure I do, twin 14's. :0
> Ok, no not any more, more bottom time was one of the compelling reasons for
> my going the (home assembled) rebreather route. My rig ready to go, with
> those twin 14's, weighs less then an aluminum 80. The price wasn't all that
> much more* then a couple high capacity low pressure steel cylinders and
> high end regulators + the manifold. (*and maybe less then some)

Ron doesn't have a clue as to *why* you would have doubles instead of
one
large single.  The fact that having redundant gas (i.e. doubles with an
isolation manifold) is one of the primary reasons for doubles, plus,
one reg comes from each primary post, is beyond his reasoning ability.

> I wouldn't bother assembling a pair of aluminum tanks, if I was doing it
> again. The cost of all the rest of the equipment is still the same and  the
> capacity of a pair of so called 80's isn't that much more then some of the
> single high pressure steel cylinders available today.  (this isn't to say I
> haven't made up a quick set of doubles out of material available, for a
> specific dive, that inclined twin 80's)

High pressure steel tanks pretty much suck anyway.  If you really wanted
ONE
single large tank for god knows whatever reason I'd opt for a single
lp steel 120.  But, stick with the double 80's for uniformity of gear
configuration
in all environment.

> So big steel tanks full of breathing mixture, isolating manifold, twin
> regulators, a stainless steel back plate (doesn't really matter whose) high
> lift wings and . . .  a hernia.  (not  joking, it happened to a dive buddy
> of mine) All add up to quite a bit of cost.  Consider the costs to the
> benefits carefully.

First, you almost would NEVER use the twin steel tanks AND a SS
backplate!!!
You should NOT need "high lift wings" unless you're doing some heavy
staging,
something that needs perhaps a 72 cu ft O2 bottle - and THAT means that
it
is most likely NOT an ocean dive because if you need MORE O2 than you
can put
in a 40 something is wrong!!!

>                                                 Best Regards
>                                                       Ron in San Diego
>
> Diving in San Diego
> http://www.diegoweb.com/diving
> [log in to unmask]

Carl