>  (Sidetrack: What is a scuba and what is not a scuba, exactly, by current
>word usage? (I am English and was brought up to use the word "aqualung" for
>open-circuit sets.) The word started as USA naval for "Self Contained
>Underwater Breathing Apparatus" and at first seems to have meant frogmen's
>oxygen rebreathers. A USA sport diving manual that I read in England in the
>1960's talked about "air scuba" (= open-circuit with a regulator) and
"oxygen
>scuba" (= rebreather). But recently I have seen a tendency to use the word
>"scuba" for open-circuit sets only.)


SCUBA in the USA is a (mainly) archaic term differentiating
a free swimming (IE Untethered) diver from a surface supplied
diver, nothing more. "Aqualung" was/is the trade name for US Divers
open circuit SCUBA, and for trademark reasons was/is not generally
used here as a generic term. Interestingly, the Russian name for
SCUBA equipment  is 'Akwalung' so take trademarks for what they
are worth!


> I am certainly less agile in the water with a modern aqualung with up to 5
>hoses radiating from the cylinder top (2 regs, to stab, to drysuit, to
>pressure gauge) and a cylinder boot giving the cylinder a square back end,
>and a stab with irregular surface contour causing yet more drag, than with
my
>first 1960's Submarine Products aqualung with one long thin cylinder with a
>round back end without boot and no stab.


George Hoffman, late Captain of the Sea Lion, who was my mentor, dove
the most arduous wreck in the NE clad in a 3/16 wetsuit, fins, gloves,
twin 72 set with a reg and pressure guage, depth guage and watch, and
8 pounds of lead. That was it. He added a poney for long deco dives and
a line reel for off-anchor deco. He was -sleek- long before sleek was in
vogue.
So as the equipment manufacturers used the word 'safety' to sell more and
more gear, we got fatter and fatter with our rigs. There is a quick point of
diminishing
returns here, though. We have gotten away from poney bottles and gone back
to
what essentially are twin 72's (we call them 104's now and pump the shit out
of them), with ideal manifolds, creating a system that looks more like
George's
'Ur-Rig' than the overloaded wreck divers of 10-15 years ago. So the more
things
change, the more they stay the same. The only people thinking that this is
something
new are the guys who only saw the sport 10-15 years ago compared to today.
If
they had seen the rigs 20-ish years ago they would immediately recognize
it's
simplicity and beauty and would be able to compare it to the (equally
elegant)
way that we usually rig now.

-But-, and I mean this sincerely, there are more than one way to do all of
this,
and for -some- diving applications drag is not nearly the issue that it is
for
others. A scootering diver going into a cave requires absolute minimum drag.
A boat wreck diver can very likely stand a lot more, especially if his
diving is
based on excavation of a small area of a sand-filled wreck. He really only
swims the length of the boat to the anchor line, descends, makes his way to
a site where he might spend an hour not moving more than two feet and
then back to the anchor line. So once again, use the correct tool to hit the
correct nail. A Cave-divers gear is 80% common in rigging and use as a
deep wreck divers gear. But that 20% difference should be recognized as
a valid change for environmental changes. Carriage of tools is not a cave
divers mission. Nor is setting up an 'off anchor-line' deco system. But
I'm not nearly as dependant on lights as a cave diver. And I deal with a
much
less benign entry/exit situation, so my gear must be tight to work in the
splash-zone. There are many small changes, but the core techniques are the
same.


> I have dived with a naval frogman type oxygen
>rebreather and with a 40-minute duration oxygen rebreather called a Salvus,
>and the improvement in underwater agility is astonishing.

Which is why several of us are using such equipment now. I'm replacing
my O/C gear with a mixed gas rebreather, and am doing my shallow stuff
with a pure 02 rebreather not all that different from the old Salvus.

The more things change, the more they stay the same.



 >Sorry, but in diving what is DIR? (except an MS-DOS computer command)

It's a new name for what the thoughtfull divers have been doing for years.
No-protruberance rigs. Thoughtfull practice. Redundancy without complexity.
Doing it Right. Problem is that a minority believe that the DIR system
should
not be fluid and allow changes for differeing circumstances, and it's these
dogma laden folks that make it miserable for people specializing in diving
in
areas that their critics are inexperienced in by telling the specialists
that they are
stupid for applying the correct technique to the correct situation.

Hey, I -can- drive a tack with a sledgehammer. But since I have a
tack-hammer
too, why not use it when it's needed?


Dave Sutton



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