I have recently completed my trimix training and was fortunate to be Billy's
buddy on the first DIR only dive on the Birchgrove Park - a 50m Sydney
wreck. 

I had been using 40% and some Pyle stops for my deco prior to mix training.
I was becoming interested in starting my deco deeper and coming up the last
20 to 25 m a lot slower. On my mix training we used 60% for deco, one deep
stop and a 10 mpm ascent to deco at 9 m - I felt wacked after those dives. 

On the Birchgrove Park dive I had some predive discussion with Billy as to
profiles and I was happy to go to 50% to commence 2 mins deco at 21m after
stops at 40m - 1 min and 30m - 1 min. Therafter stops at 12m, 9m, 6m and 3m.
The 21m stop at PPO2 of 1.6 got my deco going and allowed some cushion for
the shallower stops. I can only say that I felt on top of the world after
this and similar dives. I like this method as it keeps the ascent rate from
depth under control and opens up the oxygen window well down.

Regards
Steve Bliim

-----Original Message-----
From: Simon Murray [mailto:simonm@ho*.co*.za*]
Sent: Tuesday, 6 June 2000 21:23
To: billy@bd*.co*.au*; Tech Diver
Subject: Re: Deco gas selection


Billy,

I agree completely.  Since I started using Decoplanner, standardised gasses
and an EAD of
30m I almost always feel superb after doing deco.   About two weeks ago, I
did a
reasonable 40m dive on Saturday, drove home almost straight afterwards
(about 3 hours) and
then cycled 100k's very hard on Sunday.  I felt full of energy after the
dive and
absolutely superb on the bike the next day.

This is in contrast to when I first started diving, when I would plan diving
trips for
periods when I wouldnt be training or racing because I knew that I my power
output would
be significantly less for a couple of days afterwards.

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.


Regards,

Simon


----- Original Message -----
From: <billy@bd*.co*.au*>
To: Simon Murray <simonm@ho*.co*.za*>; Tech Diver
<techdiver@aquanaut.com>
Sent: Thursday, June 08, 2000 12:49 PM
Subject: Re: Deco gas selection


> At 10:43  5/06/00 , Simon Murray wrote:
> >Billy,
> >
> >Maybe something interesting will come out of the dr buttcrack thread.
> >
> > > I also
> > > fill my deco cylinder with 50. You, being ignorant about advanced
> > > diving, will be surprised to learn that 50 is the optimal
decompression
> > > gas for dives down to 60 metres, beyond which the addition of a
> > > sling of 02 makes the ideal deco combination for dives to 90 metres.
> >
> >I have also noticed that when using software that uses gf's to control
ascent (in my
case
> >Decoplanner), the software will give you a shorter deco using 50% rather
than 100% in,
for
> >example, a 30min 40m dive.  I assume that this is primarily because you
open up the o2
> >window earlier in the dive when you get on to the 50% and because you are
starting deco
> >deeper due to the gf settings.
>
> Deco is a lot more organic than any of the planners and algorithms allow
> for. So I just use the three principles of good deco on all my dives.
>
> I run a straight Buhlmann 12, and when Im writing up my tables, I stick
> in a one minute deep stop every ten metres to 21, where I add a 2 minute
> stop on 50. Then I resume the straight Buhlmann.
>
> In the water, the result is a much lighter, friskier feeling on the
shallow
> stops. There, the better I feel, the more inclined I am to decide to
shorten
> the shallow stops by about the same amount of time that I manually added
below
> 21.
>
> Or if I feel heavy or fatigued or unfit, I just leave the shallow stops as
> they are.
>
> This is a noticeably easier-on-the-system deco procedure than any other I
> have tried.
>
> I've recently been diving with someone who was formerly decoing on 80, but
> after using 50 from 21 metres instead, he says all the usual post-dive
fatigue
> has just disappeared.
>
> If I hadn't found out about deep stops from Richard Pyle and trimix and
> good, intelligent deco practises from George and the WKPP, I doubt I would
> still be deep diving. Like I said, the organic approach feels much nicer.
>
> rgds billyw
>
>
> >However I have always choose to use 100% as my first deco gas (adding in
50% and 35% as
I
> >move deeper or stay longer).  The reasons are primarily the same as those
for not using
> >80% as a deco gas.
> >
> >Am I missing something missing here ?
>
>
>
> >Simon Murray
> >South Africa
>
>

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