what reasons have you seen people not pass certifications?

[hypertech]

From the 2010 manual pages 44-45 (and it hasn't changed since I was an instructor).:

14. Respond to air depletion by signaling “out-of-air” in
water too deep in which to stand.

5. Respond to air depletion by signaling “out of air,” and
securing and breathing from an alternate air source
supplied by a buddy. Continue for at least one minute
while swimming.

Right, but that doesn't say anything about shutting off the tank. One could "respond to air depletion," by an instructor pointing at you and saying "You are out of air," and the student responding appropriately. I can think of many ways to do that from signaling, to spitting out the reg and holding it in your hand, to blowing off most but not all of your air to shutting off the tank completely.

 

[Diver0001]

When I teach the OOA exercise, I don't shut the student's air off completely, because it teaches nothing. Instead I shut it off and crack it slightly open, watching the gauge until I see it wavering near zero. The diver will feel that it is hard to breathe rather than simply go out of air.

I turn it off completely for the simple reason that it's a better approxmimation of reality. In reality modern regs are so good that they'll breathe completely normally until the tank is to empty that you can crack open the tank valve and hold in whatever air is still inside by covering the hole with your finger. Believe me, i've tried it.

What i want students to take away from that exercise is the awareness that if they don't check their air regularly then their gear (especially if the reg is a "high end" one) isn't going to give them *any* advanced warning that the tank is empty. One breath.... two if you're lucky. That's what they need to learn from that exercise and experiencing the reg getting "harder", while relevant to older unbalanced pistons is no longer relevant for modern balanced 1/2nd stages like many of the better regs on the market now.

Once again, high-end regs don't get harder... they just suddendly stop working. I'm sure some wise a$$ who has never run a tank dry is going pipe up that I'm full of it etc etc but my advice would be to go and try it (IN PROPERLY CONTROLLED CIRCUMSTANCES). I did it sitting on the couch watching TV and that's a good enough test to see what I'm talking about. The simple fact is, that if you're unaware enough that you let your tank become empty without noticing then it's highly probable that when it does happen it will come as a complete surprise. In my couch test my first warning that the tank was empty was about 2 breaths before it wouldn't deliver any air. In contrast, I repeated the test with an old unbalanced piston I have around and it did become noticably stiffer a minute or two before it wouldn't deliver air anymore.

Either way I believe the value of the excercise isn't to experience the fact that the reg stops working (lor gets stiffer) when the tank is empty but to see how quickly it happens so you can drill it into them that they must constantly be aware of their air-supply. YYMV

R..

 

[Diver0001]

Right, but that doesn't say anything about shutting off the tank. One could "respond to air depletion," by an instructor pointing at you and saying "You are out of air," and the student responding appropriately. I can think of many ways to do that from signaling, to spitting out the reg and holding it in your hand, to blowing off most but not all of your air to shutting off the tank completely.

PADI is usually pretty literal about the wording of these things. To my way of thinking your air isn't "depleted" if the tank is still open and you can breathe. I don't see the point in pretending to have their air depleted when it's a simple matter to ensure that it really is.

Moreover, it's my personal conviction that students should experience these things (if ever) in controlled circumstances with an instructor ready to help them if needed. The worst thing you can do to your students with respect to these skills is to pretend that the air is depleted, allow them to keep breathing while they're doing the OOA protocol and then set them loose on the world unprepared for the fact that if it ever *does* happen for real that it will happen completely differently than you taught them.

That's how I see it, at least.

R..

 

[hypertech]

I agree that its a good skill to practice. I was more commenting that I was surprised it wasn't more explicit in the standards when I went to go look for it. If that's what they really want for all students to experience, I would have thought it would have said something more explicit like, turn off air, perform out of air drill when depleted.

 

[halocline]

P1/V1 = P2/V2
Pressure in the tank is P1 Outside pressure is P2....

I tried to quote what I think was your response (in red) to boulderjohn's comment about intermediate pressure but it didn't work. Anyhow, if what you meant to say was that IP is a constant 140 PSI, that is incorrect. IP is 140 (or X) over ambient pressure. That's depth compensation and no regulator would work without it. IP is the amount of pressure it takes to close the first stage so that no more air from the tank gets into it. That's how it supplies this constant pressure to the 2nd stage. Because part of the 1st stage is exposed to ambient pressure, as you descend this pressure acts in opposition to IP, and results in a corresponding increase in the amount of pressure needed to close the 1st stage. Piston and diaphragm 1st stages have a different anatomy but the basic working principle is the same.

I have a feeling you understand this and there is just some miscommunication here.

 

[ronbeau]

While we're on the subject of not passing, can I ask about the written final exam?

I'm not a numbers guy and was somewhat nervous about the PADI written exam because sometimes I struggled with repetitive dive planning via the Dive Tables. So I asked my Instructor several times how many questions I could afford to miss but still pass.

He never gave me a straight answer. Instead I got "You'll do fine," "We'll review the exam as a group when everyone's finished" etc.

If I remember right, it was a fifty question test and I missed two, neither of which had anything to do with the Dive Tables. A minor miracle.

But I couldn't help but get the feeling I could have missed all 50 of them and still passed the exam, although I'm sure that can't be true. If anyone knows the answer, I'd love to know.

My open water instructor is a NAUI Course Director.
He required a grade of 90% or better on the written exam to pass.

If someone was close to 90% he would go over the questions they got wrong to determine whether the student actually knew the correct answer but got it wrong because of how the question was worded.

The minimum NAUI requires to pass is 70%. NAUI sets minimum standards and encourages their instructors to exceed those specifications.

I took the other NAUI courses with one the other instructors who is also a NAUI Course Director and he has the same requirements.

In fact, I challenged a few of the questions in my rescue and master diver exams and explained my reasoning.

I had more than 90% in both cases without challenging the questions. I did so based on principle.

 

[Bogie]

I saw two divers refuse to make the 2nd dive of the day because they were just too cold. Some of those rental wet suits don't fit correctly and the new divers get cold fast.

 

[FWADIVER]

Yes, def seen that, I did open water with my wife and another couple. the other female got her chest below the waterline (51 degrees) and started gasping and couldn't breathe. Ended up sitting all the dives out, and is planning to re-do when the water gets warmer.

 

[Fish in a Barrel]

With regard to breathing a tank out of air, I did an unscheduled version of this in my pool session. I was sucking air like a madman and just ran out as we were getting out of the pool. Maybe I just didn't have enough experience to notice it, but there was no change in breathing that I could sense until I suddenly had no air. It was a Mares Prestige 12 reg, for what it's worth.

I definitely learned a lesson about frequently checking my gauges.

 

[Diver0001]

With regard to breathing a tank out of air, I did an unscheduled version of this in my pool session. I was sucking air like a madman and just ran out as we were getting out of the pool. Maybe I just didn't have enough experience to notice it, but there was no change in breathing that I could sense until I suddenly had no air. It was a Mares Prestige 12 reg, for what it's worth.

I definitely learned a lesson about frequently checking my gauges.

This is exactly what I was trying to get across a few posts ago. Thanks for posting your experience.

R..