Thanks for your replies Garf, its got me thinking
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| Originally Posted by Garf I said we can do nothing about the isolator. We can certainly do something about the manifold. By closing the isolator we can isolate leaks at the point where the isolator joins the right and left posts. A leak at one of these points will result in the los of all gas from one cylinder, but isolating limits it to one cylinder.  |
Ok, you know I already know this. I accept that other agency's teach isolate first because that way you will save maximum gas (in the side that is unaffected - if the isolater valve is the problem well you're gonna lose it all anyway). I also accept the DIR reasoning that the problem is more likely to be the post doing most work (so by isolating it you save more gas...). Ok I see that by shutting the RH post you haven't eliminated the RH manifold connection so you check that next..
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| Originally Posted by Garf "just F'n do it" is actually what we are trying to avoid. the DIR approach is to think about what might be wrong and diagnose the problem, rather than leaping in. Other approaches might then take a "OK, now calm down and diagnose the problem", I guess DIR just tries to do that from the first step. |
Ok the next time a kiddie runs out in front of my car I shall try diagnosing the problem rather than just doing the SOP drill - which has been well thought through well in advance - of the procedure known as an emergency stop....... why do I hear bang splat! in my head??
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| Originally Posted by Garf Becuase hopefully none of these failures will occur and we get to take advantage of having all that extra gas. It's the same logic as using thirds. Using thirds means a team of 3 divers comes up with a spare twinset of gas between them. How is that any different from us planning to keep enough to get two divers up to the next gas source? Using DIR's principle of minimum has means we always reserve enough gas to get outselves and another diver up to the next gas source, whether that be a gas switch or the surface. That's a calculation that tells us how much gas we need should one diver lose ALL their gas. It's just a gas rule like thirds is, with a little more refinement as it is calculated based on depth.
However, you've just got me thinking, and expect another thread on this subject imminently |
Following this through if you had only a single cylinder, you isolate it but rely on your buddies supplies. This logic only works for teams of three, and only for one failure - whats the risk of multiple failures? I dunno but its got to be a lot lower than the risk of a single one. If you depart from self-sufficiency surely this is the next logical step? And then...
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| Originally Posted by Garf When I had to go back and redo part of the TDI deco procedures course, I had to go back and do a valve drill. However, in Tech1 we stand or fall on our drills as a team. Whilst there is a team element to TDI training, and perhaps you emphasise it more than other instructors I have met, I do not believe the team element is as rigidly enforced as in GUE training. |
Why, if GUE stand or fall on teamwork, are you doing your own shutdowns / diagnosis? Surely it is more logical for the member who can see your manifold and see whats happening is going to be able to go straight to the problem?
(OK for the type of diving GUE was born out of, your team are unlikely to either be able to see or able to access your valves)
H'mmm, as always I find the GUE approach to be thought provoking.
Cheers, Paul