Valve Drill Logistics

[limeyx]

I can't accept the last step is "isolate and wait for buddy."

Well, obviously if your buddy is nowhere to be found, you aren't going to sit there waiting for them However, if they are not present then you are kind of running out of options assuming

- you already isolated
- cannot see the bubbles.

Yes, you can do stuff like look if the SPG is dropping, but it's mostly guesswork.
Much better to focus on catching up with your team (who should be looking for you anyway) and have someone that can actually see the bubbles take a look.

 

[limeyx]

Thanks for your 101 on GUE training practices...of which I am fully aware of...just don't follow that way of 'one size' fits all way of doing things. This is not a GUE thread as I read it.

do it easy, this is a good and interesting thread by the way.

You are welcome.

I dont think I brought GUE up in the first place-- just pointed out that the GUE way is that everyone does it the same way, not arbitrarily does whatever they "think is better" after the class.

 

[limeyx]

At this point, I don't think that I would change anything. I think the one thing that I learned was that valve drill and valve failure procedure are two different things, although in my mind, they should be the same.

Ideally they would be the same, but I think it's hard to do (hence the valve-drill and intensive "scenarios" in class)

To do the valve-failure procedure I think you really need a person behind you with an airgun (or a purged 2nd stage) throwing different scenarios at you, and that role really belongs to an instructor, not a buddy during practice.

Sometimes on a shallow dive I will pretend to have had a bubble problem and ask my buddy to look but this really only works for "non-isolation" cases and since I "know" the failure is not really for my benefit.

The solution to diving with new divers unfamiliar with doubles is
- do a practice dive first
- bring along a more trusted buddy that knows doubles as well
- treat valve failure like OOG and go on their long-hose

 

[limeyx]

To me it seems strange that people want to separate "the drill" from "response to bubbling"...
You can but to me it seems a waste not to "use" the drill to also build the muscle-memory of "response to bubbling"...


If you know where the bubbles are coming from then adress the known "offender" but if you don´t, go for the isolator...IMO...despite my rather limited diving experience I´ve seen at least three real failiures where the diver couldn´t identify the source of the leak...

ymmv...

GUE goes for the right-post because they deem it "most likely" to fail, because
- generally you breathe it more than the left
- you yank it around more in practicing OOA drills
- you yank it around more in modified S-drills

isolating 1st is a tradeoff. You may save 1/2 your gas, but in 1/3's thats still likely to end up with you on someone elses long hose at the end of the dive as you will breathe more gas on the exit than the entrance (although maybe not so in high-flow)

if you "guess right" (literally), you may (may) save way more than 1/2 and be able to exit on your own gas.

Of course, these things happen pretty rarely so getting reliable stats may be pretty difficult.

 

[limeyx]

About unidentified leaks uw:
I´ve seen a ds inflator hose unscrew enough to bubble significantly, the diver couldn´t locate it...
Another had a 2nd stage unscrew from the hose, resulting in a bubblebath (on a single-rig)...
Both on a 1-week liveaboard...I just don´t think "unknown failiures" are that rare...

ymmv

Second-stage coming off on a single is OOA
I also would like to hope that most of us could visually ID which second stage had a huge flow of bubbles coming off of it!

I've seen plenty of "leaking posts" but 99% are caught on the surface bubble check.
Almost all have been dirt in the DIN O-ring and easily fixed.

We had one 1st stage failure with a busted piston O-ring (open water) where the 1st stage (Scubapro MK25) stopped delivering gas at around 40 feet.
There were minor bubbles on surface but nothing that looked "dive-threatening"
Diver switched to necklace and we ascended.

plenty of leaking SPG hoses on deco bottles, but generally nothing that leaks a huge amount of gas and not really too much you want to do with a slow leak in a deco bottle for the kind of dives we are doing.

 

[grazie42]

Second-stage coming off on a single is OOA
I also would like to hope that most of us could visually ID which second stage had a huge flow of bubbles coming off of it!

But that´s the thing...the 2nd stage was bubble-less (the hose completely disconnected from the 2nd stage)...the hose was flapping aroung turning his world into a jacuzzi and since it was his backup he was pretty confused about were the bubbles were coming from...the look on his face as one buddy donated and another started turning off his air was pretty funny...anyway it would look pretty much the same way on doubles as singles (except for the OOA)...

I agree though...this is pretty much one of those academic discussions and as long as you are consistent in both your valve-drill and response to failiures, do whatever makes you happy...

 

[limeyx]

But that´s the thing...the 2nd stage was bubble-less (the hose completely disconnected from the 2nd stage)...the hose was flapping aroung turning his world into a jacuzzi and since it was his backup he was pretty confused about were the bubbles were coming from...the look on his face as one buddy donated and another started turning off his air was pretty funny...anyway it would look pretty much the same way on doubles as singles (except for the OOA)...

I agree though...this is pretty much one of those academic discussions and as long as you are consistent in both your valve-drill and response to failiures, do whatever makes you happy...

True, but how does your "isolate 1st and then right post" methodology help in the case of that diver (assuming they are on doubles) ?

 

[rjack321]

So far most people I have seen in training simulations (myself included) rarely are duped by the hardest failure to manage of all, left manifold leaking but shooting and theoretically sounding like its a right side (post or reg) failure. The way I've seen it simulated, the airgun actually had to be placed on the right side, then after the diver has shut down the right, switched to the backup, and isolated; the instructor has moved it to the leftish side so the buddy is forced to undo all the "errors".

There's no valve drill simulating real failure protocols cause it just not that hard to shut down the offending side then when the bubbles don't stop isolate. None of those have been vast masses of bubbles going everywhere, in which case you'll be needing a buddy's long hose soon enough regardless of whatever you manage to shut down first.

 

[grazie42]

True, but how does your "isolate 1st and then right post" methodology help in the case of that diver (assuming they are on doubles) ?

By saving half their gas, the third you need to get out?
Whatever post you try to close afterwards will tell you that there´s a problem with the backup. If you try to close the right post first and go to your backup and start sucking water...you´ll notice...If you close the left post the bubbling will stop...

 

[limeyx]

By saving half their gas, the third you need to get out?
Whatever post you try to close afterwards will tell you that there´s a problem with the backup. If you try to close the right post first and go to your backup and start sucking water...you´ll notice...If you close the left post the bubbling will stop...

well,

1) by always going to iso then right, you make everything the "unknown" case (you are guessing right instead of looking/feeling)
2) You only benefit in your case if a tank O-ring or burst disk goes. If you do not isolate first, you "gain" gas in all other situations (except where the isolator itself fails then we both lose as there is nothing you can do)

So essentially you are betting that a burst disk/tank valve/O-ring is more likely to fail than a 1st or second stage, and I am betting the other way. If a regulator goes (1st or 2nd) I have more than 1/2 gas left and more than in the isolate first case.