Reduntant air supply? on stoney dive!

"No. If it's an emergency reserve you take it home with you along with
your ordinary 50 bar reserve. Otherwize you're just diving an 18L.
If you're diving "an 18" you're probably solidly busting the NDLs so a
pony is a bit suspect as a reserve. When something breaks you're
going to get bent."

This is good advice.

My pony gets checked before each dive, and then packed away neatly after the
dive. Apart from practice deployments/shutdowns etc in the pool, it has yet
to be used, and God Willing it won't be. It's the one piece of kit I was
happy to pay money for and NOT use.


--
Gareth Burrows



"Nigel Hewitt" <nigelh@REMOVETHISnigelhewitt.net> wrote in message
news:bp37fl$bnk$1@titan.btinternet.com...
> Sean Houlihane wrote:
> > OK, so we've accepted that redundancy is good, and that there are a
> > couple of mounting options for a pony. How about some suggestions on
> > using it and potential problems?
> >
> > If it makes any difference, I'm using it with a 15l tank, and just
> > air at the moment - and I've got a proper gauge on the pony.
> >
> > I'm assuming that a 3l pony ought to be enough air for a controled
> > surface from any non-deco dive?
>
> Some people will say no but they do it by quoting 'panic' breathing
> rates and if you have a pony you don't need to panic quite so badly.
>
> > Does that extra air make any difference to how much I can budget to
> > use? Surfacing with 50x15 + 200x3 seems generous,
>
> No. If it's an emergency reserve you take it home with you along with
> your ordinary 50 bar reserve. Otherwize you're just diving an 18L.
> If you're diving "an 18" you're probably solidly busting the NDLs so a
> pony is a bit suspect as a reserve. When something breaks you're
> going to get bent.
>
> > how does this compare with how you'd plan using a twinset?
>
> Um... On the twins I normally budgeted to bring one third back . A
> third (rule of thirds) is an old cave diver trick that allocated gas
> as one third to get there, one third to get back, one third to bring your
> buddy back. If I'm doing proper gas usage calculations I reckon on
> gas to do the dive then twice the deco so, again, I have as much as
> it would take to pull my buddy out from the worst point in the dive.
>
> nigelH
>
>

> My pony gets checked before each dive, and then packed away neatly after
the
> dive. Apart from practice deployments/shutdowns etc in the pool, it has
yet
> to be used, and God Willing it won't be. It's the one piece of kit I was
> happy to pay money for and NOT use.

One thing it is good for is those dives where you spend a long time
travelling at 4-6m. In Stoney, that would be around to the plane or the
galleon, where you spend 10-15 minutes just swimming around at 6m (I don't
like surface swims!). On the way back I don't see any harm in using the
pony if you're getting a bit low on air, since there's a direct route to
surface within a minute even at conservative ascent rates. You could
happily drain the pony, and still keep a good reserve in the main cylinder
without any real risk, and just makes the dive last that bit longer without
having to surface swim back. Of course if you're back on your main cylinder
then thats fine, but if needed i'd use the pony rather than ascent and swim
back with a full pony and 50bar in the main tank.

David