One-hand or two-hand valve drills (back mount doubles)

[halocline]

I hear what you're saying. This is, I guess, part of the very question. Is there something about the one-hand drill that gives rise to better line control, buoyancy control, etcetera? The only advantage to the one-hand drill that I can think of (given what I know) is that one can still manipulate a light while performing a shut-down. You can't do that with a two-hand drill.

Are you confusing the valve drill with an emergency procedure for a free flow in doubles? There is a difference, in an emergency the first step is to try to ascertain where the leak is coming from, and signal your teammates that you have an emergency. If it's obvious where the leak is coming from (i.e the 2nd stage in your mouth or the one on the necklace) then you just shut down that post.

The valve drill is simply about developing a methodical way of manipulating each valve while maintaining good buoyancy, trim, and light management. It's not directly an emergency procedure. The skills developed are useful in a real leak, but steps in the procedure are different. In my cave classes I learned both.

That said, imagine you have a sudden leak in a cave or some other technical dive where you can't surface immediately and you must control your buoyancy and trim. Do you really want to be manipulating both valves at the same time? You definitely want to avoid shutting off both valves simultaneously. Even a severe leak will give you several minutes of remaining gas, and since you are diving with correct gas management, your team has enough gas to get you to the surface even if you lost everything in both tanks. So a few seconds is not life-or-death. But failing to adequately signal your team-mates and accidentally closing both your valves could certainly be problematic.

 

[boulderjohn]

Here is a thought about the "do it fast" approach.

The PADI tech course I teach requires back mount valve drills to be done in under 45 seconds and sidemount to be done in under 30 seconds. One day I was curious about the sidemount requirements, and I timed myself using my sidemount tanks. I could not do it in under 30 seconds, and I was standing in my garage with both tanks sitting on a platform in front of me at shoulder height. The valves I had simply took too many turns to be done that quickly. I later changed the valves, and it was completely different.

It reminded me of when I was first learning it backmount, using a spare set of doubles from my instructor before I bought my own. It took forever, and the instructor was very critical. Then he had to do something on his own, using those tanks, and he could not do it either. Not even close. The valves were just too hard to turn.

 

[inquis]

Do you really want to be manipulating both valves at the same time?

Shutting the isolator and suspected problem post simultaneously could be useful in a real scenario. The applicability probably ends there.

 

[Imla]

I completely agree. I had insufficient gas in my tanks the last time I needed to shut down my left-post valve. If I had started by dutifully purging my necklace regulator, shutting down my right-post valve...I would have run out of back gas.

This does, however, still leave open the question: what on earth do I practice in the pool in Calgary, Alberta, for the next 4 months? What's the best approach to practicing in advance of emergency situations? Taking what I've learned from Scuba Board today, what's the approach that (a) helps the diver think about the hierarchy of priorities for a given situation (and that hierarchy will change according to the situation) and that (b) helps the diver maintain (all other things being equal) good buoyancy control, line control, situational awareness, communications, etcetera? I really do want to be super competent at this part of diving. It feels like a challenge to become fitter and to think smarter. It's like practicing arpeggios and scales on the piano. You know you'll never play a four scale arpeggio in a real performance situation, but, if you can do the arpeggio in an artificial situation, you just know you'll be able to handle the real situation. Anyway, I think that's what I'm looking for.

This is where you mistake the DIR valve drill for a DIR valve failure procedure. The Drill starts with right post manipulations and continues via iso and on to left post. This is to teach motions. The failure procedure also includes listening and identifying the most likely valve to have a failure and then closing that valve first. IE. If you hear bubbles on the left, you don't start with the right post. You start with the left post and continue over to Iso if closing of left post didn't stop the bubbles. If closing those two valves still did not help, you may a) have a non-fixable ISO leak or b) have misidentified the side of the leak, but then you have signaled your team who will check what you are breathing on, perform a flowcheck and possibly fix the problem. If b) was the case, they will open the left post, have you switch regs, and then close the right post.

 

[lukas_manthony]

Here is a thought about the "do it fast" approach.

The PADI tech course I teach requires back mount valve drills to be done in under 45 seconds and sidemount to be done in under 30 seconds. One day I was curious about the sidemount requirements, and I timed myself using my sidemount tanks. I could not do it in under so seconds, and I was standing in my garage with both tanks sitting on a platform in front of me at shoulder height. The valves I had simply took too many turns to be done that quickly. I later changed the valves, and it was completely different.

It reminded me of when I was first learning it backmount, using a spare set of doubles from my instructor before I bought my own. It took forever, and the instructor was very critical. Then he had to do something on his own, using those tanks, and he could not do it either. Not even close. The valves were just too hard to turn.

Oh, that is very interesting. I didn't know that valves could be easier or harder to turn. Is that caused by maintenance or manufacturing? I was also wondering if companies make valves that don't require so many turns. I have to turn each of my valves five or six times before they open or close. (I imagine you don't want a valve that's too easy to close down.)

Part of my question pertains to an upcoming PADI tech course of mine. Right now, I can do a two-hand drill in 60 seconds and a one-hand drill in 180 seconds (without dry gloves). I wasn't sure if I should try to fine-tune my two-hand or one-hand drill for the course.

 

[boulderjohn]

Oh, that is very interesting. I didn't know that valves could be easier or harder to turn. Is that caused by maintenance or manufacturing? I was also wondering if companies make valves that don't require so many turns. I have to turn each of my valves five or six times before they open or close. (I imagine you don't want a valve that's too easy to close down.)

Part of my question pertains to an upcoming PADI tech course of mine. Right now, I can do a two-hand drill in 60 seconds and a one-hand drill in 180 seconds (without dry gloves). I wasn't sure if I should try to fine-tune my two-hand or one-hand drill for the course.

It can be both maintenance and manufacturing.

You should be able to do it one handed in under 60 seconds. You will be required to do it in 45 before you are done.

Here is another bit of information on the difference in valve drill ease and time.

Years ago a teenager was trying to set some sort of bicycle speed record on the Boulder Creek bike path, and he took a sharp turn on the inside (wrong) lane, where he ran head on into me, shattering my collarbone and breaking a number of ribs. My recovery took a long time. I asked the surgeon who put my collarbone back together again when he thought I would be able to dive, and I scheduled a two week technical diving trip to Cozumel and the Yucatan caves for two weeks after that.

As the time approached, I grew concerned about the lack of mobility in my broken shoulder. As soon as he cleared me to dive, I got in my drysuit and got in a pool with my doubles. Nope. Couldn't do it. Not even close. I had a few therapeutic massage sessions and went to Cozumel filled with trepidation.

The Cozumel dive shop I used (Deep Exposure) wisely suggested that I do a recreational level dive first, using technical equipment, to see if I could handle it. I put on my 3mm wetsuit and hopped in the water for the first dive. I immediately tried a valve drill. Holy cow! I had never before had such an easy time doing a valve drill. Reaching those valves was ridiculously easy. I felt like I was cheating.

 

[inquis]

I was also wondering if companies make valves that don't require so many turns

XS Scuba makes a 1.5 turn valve.

XS Scuba Modular Pro Valve

XS Scuba's Valves are designed and manufactured for long life and heavy use. The Modular Pro Valve is no exception. Valve is made of marine grade brass with triple bright chrome plating for long life p

www.scuba.com

 

[crofrog]

XS Scuba makes a 1.5 turn valve.

XS Scuba Modular Pro Valve

XS Scuba's Valves are designed and manufactured for long life and heavy use. The Modular Pro Valve is no exception. Valve is made of marine grade brass with triple bright chrome plating for long life p

www.scuba.com

Quick turn valves have their own issues with things like roll off.

 

[crofrog]

This is where you mistake the DIR valve drill for a DIR valve failure procedure. The Drill starts with right post manipulations and continues via iso and on to left post. This is to teach motions. The failure procedure also includes listening and identifying the most likely valve to have a failure and then closing that valve first. IE. If you hear bubbles on the left, you don't start with the right post. You start with the left post and continue over to Iso if closing of left post didn't stop the bubbles. If closing those two valves still did not help, you may a) have a non-fixable ISO leak or b) have misidentified the side of the leak, but then you have signaled your team who will check what you are breathing on, perform a flowcheck and possibly fix the problem. If b) was the case, they will open the left post, have you switch regs, and then close the right post.

Just to reinforce your point the valve drill is 3 separate excerises that are done sequentially.

1. Right post shut off, then reset
2. Isolator shut off, then reset
3. left post shut off, then reset
4. Flow check to verify all valves are where they should be at the termination of the drill...

In the failure procedure if the left post fails you shut off the left post. It you incorrectly judged the failure and there are still bubbles you continue down the failure procedure.



As far as maintaining trim and buoyancy if you can't maintain those while shutting the valve down then you need to question if your skill is suitable to be in an environment where your loss of buoyancy control can endanger you with either descending below the MOD of you gasses, ascending beyond your deco ceiling, or creating a loss of visibility or damage to the environment.

 

[Alaskan Scuba Dude]

Anyone can walk across a plank suspended seven inches off the ground. The risk is low. It's another thing to walk the same plank when it's suspended 800 feet off the ground. The risk is high. The fear factor would overwhelm your average pool bunny trying to shut down a free-flowing regulator below 330 feet. If you cannot do it in less the 10 seconds, you have have a few minutes (maybe) to make it to the next gas switch. If you don't freeze up. Real tech divers spit out the regulator when practising real simulations before switching to the backup and shutting down the offending valve.