Pony and/or buddy

In another topic the point/suggestion was made that, at least for certain
deeper dives, one should have EITHER a good/experienced buddy OR a pony.

(A "pony" is a small -- 13-30 cuft -- air cylinder with its own SCUBA.)

I suggest that because the "rule or thirds" is not typically followed
in open water diving, a pony may be necessary/desirable regardless of
your buddy's skill.

The "rule of thirds" referes to cave diving. Although it can be more
complicated with different size air cylinders, it basically sas that
1/3 of my air is for me going in to the cave, 1/3 for me going out,
and the final 1/3 as an emergency backup for my buddy. This rule
ensures that either diver in a buddy team will have enough air for
BOTH divers to exit safely at any point in the dive.

In open water this may not always work out to "thirds" because, unlike
a cave, it is alwasy possible in open water, NDL diving to ascend
directly to the surface.

However, common open water practice is for each diver to ensure only
that he/she has enough air remaining for him/herself to ascend.
So, for example, it is unlikely that at the end of a 20min, 100ft
dive that either diver will have enough air for both to ascend safely.
Thus a catastrophic loss of either divers air would leave them short
of air for a safe ascent.

I can only see three ways to overcome this:

1) Follow the "rule of tirds", modified as appropriate.

1A) This could be done by shortening the dive duration, but nobody
wants to do that.

1B) Larger air cylinders could also be used, but in may cases AL 80s
are the default and may be the only cylinders available.

2) Cary a pony tank.


1A is probably not going to happen.

1B has problems transporting a large tank for travel.

1B and 2 both entail the cost of a larger or "extra" cylinder.


So what do all you boys and girls think about this?
--
Charlie Hammond -- Hewlett-Packard Company -- Ft Lauderdale FL USA
(hammond@not@peek.ssr.hp.com -- remove "@not" when replying)
All opinions expressed are my own and not necessarily my employer's.