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In message <34CC8700@uk*.uk*.se*.co*>, "David Shimell (shimell)"
<shimell@se*.co*> writes
>
>Jim
>
>I agree with your other points that I have snipped but have some views on
>your points on the pressure gauge:
>
>> -How do you check the pressure of your pony while underwater?
>> -If you use a gauge, how do you have the gauge rigged?
>
>Why put a pressure gauge on the pony cylinder in the first place. This
>is a point of failure. Gauges are only needed on stages if they are
>breathed to thirds - you have to know the contents to know when to stop
>breathing from them.
Dave
Are you suggesting that a stage cylinder is OK minus a gauge if
'thirds' is not being applied?
>
>BSAC train the following practice. Breath your primary supply down to
>the reserve level (i.e. the pressure at which you planned to be back on
>the boat), then switch to the backup supply (pony in this case). This
>ensures that the reserve in your primary remains intact at this point and
>that the correct functioning of the pony is confirmed. Once on the pony
>it can be breathed down until breathing resistance is felt and then the
>switch is made back to the primary supply reserve.
Pony cylinders have a very limited application in non mandatory deco
diving at (dependant on your views) 0 to 30 metre range. They 'arrived'
on the scene as an emergency piece of equipment to enable a return to
the surface in the event of a total failure on the primary cylinder (we
are talking single cylinder, single pillar valve). Not sure where this
scenario you are advocating has come from - it sure looks like a recipe
for disaster to me and would smack of bad dive planning and conduct.
>
>The need for a pony pressure gauge is even more reduced if the diver
>adopts an incorrect procedure and breaths the primary dry before
>switching to the pony - you either have enough gas or you don't - a
>pressure gauge really doesn't help.
Hmmmm.... see my comment above on dive planning & conduct.
>
>The pressure gauge on the pony is a comforter and nothing else!
I thought the pony was the comforter!
>
>Now, just to counter my own point: I guess a poorly trained, poorly
>configured recreational diver (a Scubie Doo) may feel a bit aghast at the
>idea of doing a regulator switch or two in a stressed situation and even
>more aghast at not having the comfort of knowing the pony pressure.
Ah Ha - back to the old training issue - on the nail Dave!
Regards
Chris Hellas e-mail - chris@de*.de*.co*.uk*
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