I think everyone's made some really good points in this thread. But I am
nonetheless compelled to put in my $0.02. Some of the boats here in the NY
/ NJ area list a redundant air supply as *required* equipment if you want
to dive off the boat -- along with equipment that I think you agree is
necessary, such as a reel, lift bag, cutting implement, etc. Do you suggest
that if I want to dive with a single tank, I should not dive off of one of
those boats? Do none of the boats in your area have equipment requirements?

To my knowledge, the Wahoo does not require a redundant air supply. But
when I was a brand-new wreck diver, I didn't dive off the Wahoo much
because at the time, they mostly went to the Oregon and the San Diego. I
didn't feel ready at the beginning to dive the Oregon, and, well, I like a
little variety, so I was diving on other boats, too (which required the
redundant air supply) in order to visit wrecks such as the Lizzie D, Stolt,
Algol, Iberia, etc. 

When dive season begins again here, I will probably spend April doing what
I did last April: diving with a single. It's just way too cold for me to
want to stay down long enough to incur deco, and my hands just don't work
real well in super-cold water, so I'm not interested in penetrating the
wreck (yes, Virginia, there are things to see on the outside!) -- neither
of which I would do without doubles. And I freely admit that climbing the
boat ladder with a single tank (with or without a pony) in the heavy seas
of the early season is a lot easier than doing it in doubles. 

No matter what I do, I seem to be powerless to prevent people on the same
boat as me from diving solo and / or failing to manage their own gas supply
properly. If some giant hoover runs out of air and grabs the reg out of my
mouth, I'm not so sure that there would be enough gas for us to return to
the anchor line, ascend slowly and do a reasonable safety stop. What if I'm
all the way at the other end of the wreck and this guy has a consumption
rate five times mine (not an unreasonable assumption)? Perhaps the OOA
diver is not a hoover per se, but is a fairly new diver and freaked out
enough by the situation to use more air than normal. 

So here are my options as I see them:
(1) Stop using the pony, and practice the tried and true rule of "my air is
my air." 
(2) Skip diving when the water is too cold for me to want to do dives that
require me to use doubles. 
(3) Maybe I should only get in the water when everyone else is on the boat? 
(4) Stop diving off boats that accept giant hoovers, people who don't
manage their gas and buddyless divers. (No such boat exists to my
knowledge. As far as those that require buddy diving, it's a little hard to
control what the buddies do once they get in the water.)
(5) Dive with doubles anyway. But wait, according to my limited
understanding of "DIR," diving with extra unnecessary equipment (did you
say "Christmas Tree?") is just as much of a sin as having wrong or
improperly configured equipment. 
(6) Manifold a couple of 45's -- like you suggested -- for my early-season
single-tank diving. That would give me redundancy the "right" way, but it
still wouldn't solve the hoover problem. 
(7) Calculate my thirds as a hoover would, yielding 7 minutes of bottom
time instead of 30.
(8) Use a 120 cu. ft. tank and calculate my thirds as the hoover would,
yielding 10 or 11 minutes of bottom time.

Is it me, or do all these seem like impractical solutions?

As far as the 6 cu. ft. bottle goes, well why not just carry a Spare Death
instead? 

You made a lot of really good points in your bulleted list. But I just
can't see the disadvantages outweighing the advantages.

>If you can't reach the surface with the air that's in your tank after
you've had a LP hose failure you should not be diving.
I can't add much to what Lisa said about this. However, because of some
kind of paranoia I have (I'm sure its complete strokery and perhaps you
will instruct me on this), I prefer to get back on the boat with 500 psi of
air in my tank. If I have the pony bottle, and all kinds of stuff has gone
wrong, I don't have to worry about sucking my main tank dry.

>You get a DIN valve to get rid of the "oring failure phobia".
I already have DIN valves on everything. I'm really happy to learn having
DIN valves means that nothing can possibly go wrong.

>How about inspecting your gear before you dive in? Oh, to hell with that,
I've got a PONY.
If inspecting my gear before I dive means that nothing can possibly go
wrong with it, then why bother with redundancy at all, ever? 

>So you're telling me that you can strap a 40lb piece of lead to the side
of your BC and not feel it? 
>Oh, come on, it's downright comical to see the ponyboys stagger around the
deck with their silly 
>jacket BCs half pulled off from the pony bottle.
Thanks to the wonders of modern technology, pony bottles are available in
sizes other than 6 cu. ft. and 40 cu. ft.! 
My pony bottle is 19 cu. ft. According to my calculations, it provides more
than enough gas for me to ascend slowly from 130 ft., do a 5 min. safety
stop at 15 ft and get back on the boat with plenty of air left over. Off
the top of my head, I don't know what the buoyancy characteristics of an
aluminum 19 cu. ft. tank is, but I can honestly say that it is not
noticeable in the water compared to my light, which, when used with a
single, DIR-style, is pretty unbalancing. (Since I don't carry the "right"
kind of light, my light is only 1 1/2 pounds negative in the water.)  Maybe
I should carry a hand-held light if I'm doing single tank diving.

Furthermore, in the unlikely event that all hell broke loose and I lost all
my gas instantly I could ascend directly to the surface on one breath. But
I'd really rather have the option of heading back to the anchor line and
doing a safety stop. This is probably due to some unreasonable phobia of
mine, or didn't I hear somewhere that "all diving is decompression diving."

I will admit it, on two occasions I have needed to use my pony bottle. Both
times were in no-deco situations, and I didn't have enough gas in my tank
to complete my safety stop without draining my main tank below 500 psi.
This was due to complete and unforgivable strokery on my part. I made a
mistake. And I learned from it.

All things considered, I think I'll carry the pony for single tank diving.
Hopefully I will never *need* it.

Now pardon me while I retreat back into my shell.

Maggie;
Maggie, who seems to be a northeast-wreck-diving-geek-using-stroke-gear
mmowens@pa*.co*
http://www.panix.com/~mmowens
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