Peter

Excuse me for responding to this thread which is so old it must be
thread-bare.  Your original question related to the procedure for gas
switching in the ocean whilst doing drift deco, and probably in cold
conditions.  Your question for DIR divers was as follows:

>When you move from 50% to 100%: then you have 2 hoses to look after. It's
>the gas switch procedure I am interested in.

I did a few dives back in the UK and wanted to try out some ideas in more
comparable conditions.  The following is the procedure I have adopted.  So,
you're ascending on 50% and get to your 6m stop, do the following:

Switch the DSMB reel to the right hand.
Switch off venturi on 50%.
Remove 50% regulator from mouth with left hand and let it drape down your
front.
Use left hand to go to your backup (bottom gas).
Turn off 50%.
Unclip the waist clip of the 50% cylinder and pull around and forward to make
the cylinder more accessible.
The cylinder remains attached to the diver by the neck clip.
Transfer the clip and tail of rope from left to right hand which is still
holding the DSMB reel.
Remove 50% regulator from around the neck with left hand.
Re-stow the 50% hose under the inner tubing on the cylinder.
Transfer clip and tail of rope on 50% cylinder from right to left hand.
Re-clip the 50% cylinder to the waist D-ring.
Re-pressurise 50% and confirm it is switched off.
Un-stow O2 regulator with left hand and spit out the backup.
Insert O2 regulator into mouth with left hand.
Verify cylinder MOD markings (on the neck) and turn on O2.

I tried this with three finger mitts in 12-14 deg C conditions with no
problems.  I also did this on the descent as my deco gas was used for travel.
Stowing the regs was much easier.  Perhaps in really cold conditions it may
be more difficult but the ease of re-stowing hoses may offset the increased
difficulty of clipping to the hip.  IMHO, re-stowing is the act which
requires greater dexterity.

In practice, I used my primary as the temporary regulator but now feel the
backup would be a better choice as it is more easily identifiable and
accessible than the clipped-off primary.  It is also the regulator least
likely to free flow.  Obviously, on a travel gas descent I would still use
the primary so as to avoid a further regulator switch from the backup to
primary.

Comments?

David Shimell
Project Manager, Sequent Computer Systems Ltd., Sandton, South Africa.
Email: shimell@se*.co* <mailto:shimell@se*.co*> 

-----Original Message-----
From:	Jess Armantrout [SMTP:armantrout@wo*.at*.ne*]
Sent:	Wednesday, May 19, 1999 2:23 PM
To:	Cost effective home improvement
Subject:	Re: Gas shifting

oh. ok, I see.  What I do is unclip the bottle I am breathing completely,
top and bottom, and push it out in front of me.  (It is never too heavy or
too light to still hold in my teeth by the reg, and usually is pretty
neutral).  I pull the next reg, check the next bottle, turn the tank on,
swap regs, stow the hose on the old bottle and usually move it to the hip
d-ring.


Jess

-----Original Message-----
From: Peter Fjelsten <fjelsten@ma*.st*.dk*>
To: Jess Armantrout <armantrout@wo*.at*.ne*>
Cc: Cost effective home improvement <freeattic@co*.ci*.uf*.ed*>
Date: Wednesday, May 19, 1999 7:56 AM
Subject: Re: Gas shifting


>Den 07:42 19-05-99 -0500 skrev du:
>>Numbers on the neck?
>
>Of the deco bottles. Then you don't have to unclip from the bottom D-ring
>which _can_ be a small hassle to reclip to with heavy mitts.
>
>>The short hose is bungeed, the long hose is clipped to the right checst
>>d-ring, the hose on the deco/stage bottle goes around my neck and into my
>>mouth.  What hoses tangled?
>
>When you move from 50% to 100%: then you have 2 hoses to look after. It's
>the gas switch procedure I am interested in.
>
>Do you take the 50% out of your mouth, park it and _then_ unpark the 100%?
>Or do you unpark the 100% before you've parked the 50%?
>(Park: put the deco reg hose under the bungy on the deco bottle)
>
> Hilsen (That's "regards" for you English speaking folks),
>
> Peter Fjelsten
>
>
>


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