Just to clarify, before I get in the water and do it!

Essentially, for shallow, bounce type dives say bottom time up to 30 mins and
depth up to
50m (165ft), a fit diver would be better off using 50% as opposed to 100% and
extending
the 21m stop generated by Decoplan.

Would it be correct to say that using 50% rather than o2 reduces your margin
for error on
deco, because you dont have the o2 window wide open at 6m to help you with any
'cleanup' ?

I assume that o2 is always close at hand i.e. either staged or in the boat and
ready to
come down should the need arise.

Thanks,

Simon Murray
South Africa

----- Original Message -----
From: Trey <trey@ne*.co*>
To: David Chamberlin <dwc@na*.co*>
Cc: Simon Murray <simonm@ho*.co*.za*>; <billy@bd*.co*.au*>; Tech Diver
<techdiver@aquanaut.com>
Sent: Thursday, June 08, 2000 1:11 PM
Subject: Re: Deco gas selection


> Yes, but in practice for a fit diver, 50 is better as you take less
> beating if you can deco from the gradient successfuly, which I can. I
> use no deco gas if possible at all.
>
> David Chamberlin wrote:
> >
> > I'd also be interested in hearing some comments on this.  A while ago,
> > when asked about single gas usage, I could've sworn JJ responded that
> > for shorter dives in the <50m range, O2 would be the choice.  I always
> > found that curious since JJ and G seem to try and clear out their deco
> > as early as possible, which would indicate 50/50 would be the better
> > choice.  Then when trying to find the message I was thinking of, I
> > stumbled across this post from JJ:
> >
> > > If I were to be using one bottle it would be the 50. Depending on the dive
> > > I may carry two small bottles which I do a lot. On occaision we do the 50%
> > > on the first dive and if its a repet we would do the 50 and then both on
> > > the second dive.
> >
> > And then G replied:
> >
> > > JJ will answer , but he and I always choose the deep stops over the
> > > shallow, and having the better gas deep is not only in keeping with
> > > getting that part done right, it conforms to our experience. Most of my
> > > ocean dives are one gas dives - I do not generally see the need for the
> > > oxygen at all on a short hop first dive, and prefer not to take the
> > > beating of using it for not reason. On the second dive, I would take
> > > both gases. The oxygen window explanation is the correct one in this
> > > context of doing the deeper stops as well.
> >
> > But like Simon, I assumed that for a shortish, shallowish dive, O2 would
> > be the better choice for many of the reasons in the Baker's Dozen.
> >
> > Lest I be smote, I hasten to add I'm not in any way trying to impune G's
> > experience/knowledge, I would just like a clarification on what the
> > "best" single gas to use would be for a shallowish (<=50m) shortish (say
> > <= 30min) dive.
> >
> > Thanks,
> > Dave
> >
> > Simon Murray wrote:
> >
> > > I would be interested in the feedback of any other people as to choosing
to use 50%
from
> > > 21m instead of o2 as a deco gas on shallower (say up to 50m) dives.
> > --
> > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
> > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
>
>

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