I was taught all of that failure stuff and was supposed to memorize them all. I believe it is all too complicated. Once you have the main idea, it all can be summarized in a few common sense sentences anyone can understand.
Manifold failure - what should you do?
- Thread starter Daniel Dilley
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I was taught all of the failure modes and in my TDI class it was a timed event doing a valve drill. I did it, but it was a frustrating endeavor because you end up doing it by muscle memory to clear the time limit, but not really taking the time to properly sort out where a possible failure might be.
The most beneficial procedure was in my cave courses, where the procedure was not time based, but situation based, where you were judged on your ability to respond CORRECTLY, rather than how fast you could do the rote procedure. Then, when those happen during the actual exit portions of the training dives, you correct the issue without even having to think about the physical motion, because you understand the problem and how to solve it. When the isolator failure came up, and you did go through the procedure to determine location of failure, turn the dive, and breath as much of your gas as you can until you have to share the long hose on the way out. I found it all much more intuitive, and much more beneficial from an understanding of failure modes. It also prevents a student from shutting off both of their gas supplies if they forget a step.
The most beneficial procedure was in my cave courses, where the procedure was not time based, but situation based, where you were judged on your ability to respond CORRECTLY, rather than how fast you could do the rote procedure. Then, when those happen during the actual exit portions of the training dives, you correct the issue without even having to think about the physical motion, because you understand the problem and how to solve it. When the isolator failure came up, and you did go through the procedure to determine location of failure, turn the dive, and breath as much of your gas as you can until you have to share the long hose on the way out. I found it all much more intuitive, and much more beneficial from an understanding of failure modes. It also prevents a student from shutting off both of their gas supplies if they forget a step.
I have a lot of problems with the valve drill as done by every agency I know. If I were in charge, I would do it differently.
We seem to forget that there is never any time that we will do the valve drill in its entirety in a real situation. The purpose of it is to show that you can get to any valve quickly in an emergency. Going through the whole routine for total speed time (as required by some agencies) or through the beauty and precision of the movements (as required by others) is really pointless.
It makes me think of the fin pivot and the reason that PADI dropped it from OW instruction. The purpose of the fin pivot was very simple: students were supposed to learn from it that inhaling made you ascend and exhaling made you descend. That's it. A fin pivot itself is not something you ever do in diving. Instructors began to obsess over the form of the fin pivot, not passing students until they were perfect in the way they did it. Once PADI realized that instructors had lost sight of the reason for the exercise, they realized thy had to do away with it altogether.
We seem to forget that there is never any time that we will do the valve drill in its entirety in a real situation. The purpose of it is to show that you can get to any valve quickly in an emergency. Going through the whole routine for total speed time (as required by some agencies) or through the beauty and precision of the movements (as required by others) is really pointless.
It makes me think of the fin pivot and the reason that PADI dropped it from OW instruction. The purpose of the fin pivot was very simple: students were supposed to learn from it that inhaling made you ascend and exhaling made you descend. That's it. A fin pivot itself is not something you ever do in diving. Instructors began to obsess over the form of the fin pivot, not passing students until they were perfect in the way they did it. Once PADI realized that instructors had lost sight of the reason for the exercise, they realized thy had to do away with it altogether.
diver42
Contributor
I hope this adds a bit:
1. Most failures aren't catastrophic, which is to say that a few extra seconds won't make you lose all your gas. And as many people pointed out, closing the manifold won't do anything in most circumstances, so that's usually wasted time (gas). You can figure out most leaks. If the gas is rushing from one side, close the valve and purge the reg. If it doesn't stop, shift. Gas is still coming from the same side? Then close the manifold. But you may want to reopen the valve and breathe that tank down, since you're losing the gas anyway, unless you're someplace where the rush of bubbles will cause other problems (e.g., percolation/silt). If you've dinged your isolator or manifold, you probably can identify exactly when it happened. (Right before you yelled, "Oh sh!t," followed by, "[ding].")
2. Doing an exit on a closed valve is annoying. I recently did a one-hour scooter exit with a closed right post, after a reg failure. Depth changes were a real pain. If you can avoid it, it may be more pleasant to let the gas go. It all depends on the situation.
3. If you're in a cave, it may not be so simple to just turn and exit before solving or at least identifying the problem. If you have a problem that has caused you to lose too much gas to exit safely, now is the time to coordinate with your buddy—not when you run out on the way back, which will create an all new emergency. If it's your leak, you'll probably want to be up front in a two-man team or in the middle of three (in case you didn't happen to be already). Plus, a rush to exit may cause other cascading problems. You don't want to get turned around. One thing at a time. Don't rush.
1. Most failures aren't catastrophic, which is to say that a few extra seconds won't make you lose all your gas. And as many people pointed out, closing the manifold won't do anything in most circumstances, so that's usually wasted time (gas). You can figure out most leaks. If the gas is rushing from one side, close the valve and purge the reg. If it doesn't stop, shift. Gas is still coming from the same side? Then close the manifold. But you may want to reopen the valve and breathe that tank down, since you're losing the gas anyway, unless you're someplace where the rush of bubbles will cause other problems (e.g., percolation/silt). If you've dinged your isolator or manifold, you probably can identify exactly when it happened. (Right before you yelled, "Oh sh!t," followed by, "[ding].")
2. Doing an exit on a closed valve is annoying. I recently did a one-hour scooter exit with a closed right post, after a reg failure. Depth changes were a real pain. If you can avoid it, it may be more pleasant to let the gas go. It all depends on the situation.
3. If you're in a cave, it may not be so simple to just turn and exit before solving or at least identifying the problem. If you have a problem that has caused you to lose too much gas to exit safely, now is the time to coordinate with your buddy—not when you run out on the way back, which will create an all new emergency. If it's your leak, you'll probably want to be up front in a two-man team or in the middle of three (in case you didn't happen to be already). Plus, a rush to exit may cause other cascading problems. You don't want to get turned around. One thing at a time. Don't rush.
Yeah, there's more than one way to skin this cat. The bottom line is that if you're going to get into an overhead environment on a back mounted twin set then you need to be able to isolate and shut down a free flow like your life depended on it. It does.
Of course, this is yet another reason that makes side mount very attractive.
I just want to say that it is exactly this advice, repeated in so many places, that has once caused me so much grief in learning to reach my valves. It makes intuitive sense, but perhaps it does not work the same way for everyone. At least in my case, the exact opposite seemed to work best: not to look down, not to mess with loosening harness straps, and not to mess with trim.
Not everyone works the same and that's OK. Elena has to have a tail weight to stay trim. I've heard instructors trying to shame her out of using it, but it's what works for her. No shame in that. The point is, you should figure out what works for YOU before the crap flies. Then when someone is having a problem, share what works for you. For the most part, I dive sidemount when I need/want doubles so the process is incredibly simplified. I still dive back mounted doubles from time to time, like off of most boats, but I rarely need doubles then.
Bubbles where bubbles don't belong? (Ie, somewhere benind your head)
As mentioned previously, you should be able to hear what side they are coming from.
Step 1: stop
Step 2: listen and determine what side you hear bubbles.
Step 3: turn off that sides valve while signalling your buddy/team/sea lion.
Step 4: breath down and switch to a working regulator/or purge the regulator (ie, your breathing from the right valve, and you shut down the left valve, purge the left valve reg).
Step 5a: do you still hear bubbles?
Step 5b: shut off isolator (while signalling that sea lion).
Step 6: ask the sea lion to check out the side you shut down/bubbles
Step 7-a bunch:
-sea lion verifies regulator you're breathing.
-bubbles? Make sure isolator is closed.
-open up closed valve on regulator to either recreate the issue, or verify it is working properly.
-if that bubbles, shut it off and purge. Try to fix it 3 times.
-if fixed, open valve all the way (as well as isolator if it closed and bubbles have ceased)
-purge now working regulator (unclip if clipped off), and let them know it's good to switch and no issues.
-if broken, tell them it's broken.
Last steps:
Flow check, making sure that open valves are open, and anything broken is closed
Check gas, and decide on action (carry on, ascend on SMB, ascend on line, etc)
Now if you misdiagnosed where the problem was (ie, shut down right regulator, switched to left regulator, still heard bubbles and closed the isolator):
Sea lion verifies you're breathing the left reg. sees bubbles from left reg.
Open up right reg, tell them to switch.
Once switched, turn off left reg, purge and try to fix.
If bubbles just from the reg, open up the isolator.
If reg is fixed, purge that reg I front of the diver.
If reg is non fixable, tell diver.
Flow check and determine next action (carry on, head home)
-R
As mentioned previously, you should be able to hear what side they are coming from.
Step 1: stop
Step 2: listen and determine what side you hear bubbles.
Step 3: turn off that sides valve while signalling your buddy/team/sea lion.
Step 4: breath down and switch to a working regulator/or purge the regulator (ie, your breathing from the right valve, and you shut down the left valve, purge the left valve reg).
Step 5a: do you still hear bubbles?
Step 5b: shut off isolator (while signalling that sea lion).
Step 6: ask the sea lion to check out the side you shut down/bubbles
Step 7-a bunch:
-sea lion verifies regulator you're breathing.
-bubbles? Make sure isolator is closed.
-open up closed valve on regulator to either recreate the issue, or verify it is working properly.
-if that bubbles, shut it off and purge. Try to fix it 3 times.
-if fixed, open valve all the way (as well as isolator if it closed and bubbles have ceased)
-purge now working regulator (unclip if clipped off), and let them know it's good to switch and no issues.
-if broken, tell them it's broken.
Last steps:
Flow check, making sure that open valves are open, and anything broken is closed
Check gas, and decide on action (carry on, ascend on SMB, ascend on line, etc)
Now if you misdiagnosed where the problem was (ie, shut down right regulator, switched to left regulator, still heard bubbles and closed the isolator):
Sea lion verifies you're breathing the left reg. sees bubbles from left reg.
Open up right reg, tell them to switch.
Once switched, turn off left reg, purge and try to fix.
If bubbles just from the reg, open up the isolator.
If reg is fixed, purge that reg I front of the diver.
If reg is non fixable, tell diver.
Flow check and determine next action (carry on, head home)
-R
Reku
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Awesome stuff in this thread, here's my 2 psi.
All of these things are why I just SM and have no intention of going back to BM. When I see bubbles just shut it off and switch. When I need to switch back just do it and feather the valve.
All of this isolate that and twist that after the thinger has done what it does while you turn the left tree counter clockwise toward the third arm of the sun while subsequently chanting some ancient spell is just too much work for me lol. More power to you guys though
If it works for you then don't stop doing it just because some random koala thinks it's voodoo witchcraft.
and besides BM doubles are dang heavy for me.
All of these things are why I just SM and have no intention of going back to BM. When I see bubbles just shut it off and switch. When I need to switch back just do it and feather the valve.
All of this isolate that and twist that after the thinger has done what it does while you turn the left tree counter clockwise toward the third arm of the sun while subsequently chanting some ancient spell is just too much work for me lol. More power to you guys though
If it works for you then don't stop doing it just because some random koala thinks it's voodoo witchcraft.and besides BM doubles are dang heavy for me.
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