New to doubles

[Adobo]

he's taking Fundies as soon as the class is available, so he'll be learning properly, just trying to figure out the basics so he has some idea of what's going on.

That's kind of my point. The basics are, don't muck around with valve drills (until someone who knows shows you how) and failures (until you are in appropriate class). Put on the regs, make sure the isolator and posts are open (flow check) and dive the doubles like you were diving a giant single tank. That's the basics.

 

[rhuntley]

Different agencies teach valve drills differently. In the case of GUE, valve drills require two divers - the person who is doing the valve drill and a buddy who helps to make sure that the diver doing the valve drill doesn't find himself with both posts shut off. So it might be better to learn this stuff from/with someone who will be helping you do the valve drills anyway - be it GUE or IANTD or PADI DSAT. You learning this in the internet and teaching it to one of your dive buddies is a little close to the blind leading the blind.

I have indeed heard from the instructor that more than one person during the course will turn both of their posts off by mistake, or close their isolator and forget to open it, throwing them off for the next drill.

There are many benefits to diving doubles in recreational dives. However, by its very definition, a recreational dive means that if there is an emergency, the dive is over. You are not debugging failures and shutting down valves.

While I am not a technical diver, or obviously even a doubles diver at this point, I disagree. In my dictionary, in a technical dive there is no direct access to the surface. In recreational diving, there is. I don't believe that means you must take advantage of it. If there is a failure, and I am trained to handle it (which I plan to be), I am not going to be grabbing my buddies long hose without attempting to handle the situation.

Now, it may be that you want to use these doubles to do dives with technical profiles or overheads. In that case, it is indeed important to know how to debug failures and preserve gas so that you can exit the dive safely. In that case, a class might be the most appropriate setting to learn how to debug failures as there are far more considerations to sorting out failures than just figuring out which post/reg is leaking.
One last note... when diving back mount doubles with an isolation manifold, the notion of self reliance seems somewhat odd. You cannot definitively debug an issue by yourself as the manifold, posts and regs are behind your head. If your plan is to dive these tanks as more or less a solo diver, then perhaps instruction/advice on diving solo is more what you are looking for. And maybe rethink whether back mount doubles is the most appropriate configuration. Just a thought.

As said above, I plan to get in the next class available. I'll be diving doubles in the ocean before then, but I'll be leaving handling failures until with an instructor since as said above, its best to not develop bad habits. If a failure arises before I have instruction then yes, I would thumb the dive. I'd like to develop a degree of self reliance to handle a situation to the best of my abilities before resorting to my buddy intervening. I have no interest of solo in doubles. As shown by charters/liveaboards when they check certs, there is a difference between self reliant and solo.

Thanks for the advice

 

[tbone1004]

Adobo, we'll agree to disagree, if you follow the steps in the GUE valve drill, there is pretty much no way to fubar it since you are verifying everything after you do it. Did I shut it off? Well I purge or take a breath and the hose goes limp, so check. Did I turn it back on? Well I see or feel the hose pressurize, and I can breathe off of it, and I'm always breathing off of the other hose than the one I'm manipulating. Just not sure how you can screw a valve drill up following those procedures. I looked up the actual one in the GUE manual and it's like 13 steps, that are pretty idiot proof. Only time you can shut both off is if you just aren't doing it in the right order and verifying everything works before switching.

 

[Adobo]

Adobo, we'll agree to disagree, if you follow the steps in the GUE valve drill, there is pretty much no way to fubar it since you are verifying everything after you do it. Did I shut it off? Well I purge or take a breath and the hose goes limp, so check. Did I turn it back on? Well I see or feel the hose pressurize, and I can breathe off of it, and I'm always breathing off of the other hose than the one I'm manipulating. Just not sure how you can screw a valve drill up following those procedures. I looked up the actual one in the GUE manual and it's like 13 steps, that are pretty idiot proof. Only time you can shut both off is if you just aren't doing it in the right order and verifying everything works before switching.

Since you are using GUE as the example... do we even know why the valve drill is taught in fundies?

I was on a dive just yesterday where my GUE trained buddy did a valve drill. Either he did not check his backup reg for gas or I did not see it. In either case, he started turning off his right post so I stopped him just to be sure that he had a working reg to switch to.

Per GUE, it takes two divers to do a valve drill. If the OP has a trained buddy, that buddy should show him how to do the valve drill. In this way, the trained buddy can see if the the OP is doing the valve drill properly or if the OP is about to wind up with two posts that are turned off.

If the OP doesn't have a trained buddy, what is the point in learning the valve drill in the internet? Is the OP going to teach one of his friends to do the valve drill that he learned in the internet?

I guess I just don't see what the point is, especially when it is perfectly reasonable to dive doubles in recreational dives without introducing valve drills.

I suppose if I was pressed for "tips" for diving doubles prior to taking intro to tech or fundies or some sort of doubles primer, I would say, keep it simple.

---------- Post added November 10th, 2014 at 01:50 PM ----------

While I am not a technical diver, or obviously even a doubles diver at this point, I disagree. In my dictionary, in a technical dive there is no direct access to the surface. In recreational diving, there is. I don't believe that means you must take advantage of it. If there is a failure, and I am trained to handle it (which I plan to be), I am not going to be grabbing my buddies long hose without attempting to handle the situation.

Well, I can appreciate that different people have different opinions but I find it hard to get around the fact that if you have a post or manifold failure, it will take not one but two trained divers to deal with it under water. This has nothing to do with agencies and everything to do with the fact your eyes are not on the back of your head. So by virtue of you soliciting advice in scubaboard, I am inclined to think that there aren't many dive buddies around you that could help you debug a failure even if you had the training.

Regardless, in a single tank, if I have gas leaking from my first stage or the tank valve, the first course of action is not to get gas from my buddy anyway. I would get my buddy's attention, show him that I hear bubbles and then I would thumb the dive. On the ascent, I would monitor my SPG to see how fast I am losing gas. If I can, I will complete my ascent on my own reg.

Which is exactly what I would do if I were doing a recreational dive with doubles.

I don't want to be attached to my buddy sharing gas unless it is necessary.

Thanks for the advice

You're welcome.

 

[PfcAJ]

It doesn't require two divers to diagnose (or often fix) a failure. Its nice to have, but certainly not required.

 

[Adobo]

It doesn't require two divers to diagnose (or often fix) a failure. Its nice to have, but certainly not required.

I've been wrong many times before. Maybe I am wrong again.

But without a buddy (or a mirror) I can't figure out how I would determine what kind of failure I have on my post/manifold (post vs. manifold, fixable vs. non fixable, the correct post is turned off, I am breathing on the correct reg, the isolator should be on vs. off, etc.).

I also seem to recall that part of the process was supposed to be signalling to my buddy something along the lines of "you look, bubbles, this side".

What am I missing?

 

[PfcAJ]

GUE's process is a classroom thing to ingrain the relationship between your different valves and what connects to what.

In real life, the types of failures aren't limited to bubbles shooting out behind your head. 2nd stages freeflow, hoses come loose, stuff like that. Even if bubbles do start coming out behidn your head, you can self diagnose what the problem is. For instance, if you shut down your left post and the bubbles stop, the issue is downstream of the valve seat. If not, you either shut down the wrong post or its a manifold failure.

The buddy can come in and confirm, sure. Or maybe even attempt to fix. But as far as a practical diagnosis and inventory of what works, you can do that all by yourself.

 

[Adobo]

GUE's process is a classroom thing to ingrain the relationship between your different valves and what connects to what.

In real life, the types of failures aren't limited to bubbles shooting out behind your head. 2nd stages freeflow, hoses come loose, stuff like that. Even if bubbles do start coming out behidn your head, you can self diagnose what the problem is. For instance, if you shut down your left post and the bubbles stop, the issue is downstream of the valve seat. If not, you either shut down the wrong post or its a manifold failure.

The buddy can come in and confirm, sure. Or maybe even attempt to fix. But as far as a practical diagnosis and inventory of what works, you can do that all by yourself.

I agree that there are things that you can sort out without a buddy (like second stage stuff, lp inflator stuff, SPG stuff).

In terms of resolving the issue, no way that is happening for me if the problem is behind my head.

 

[tbone1004]

solution there is you can flip the doubles over your head and fix them, or do proper gear checks to make sure your hoses are all tightened before the dive, and a first stage can't come loose unless it is depressurized and turned. Pretty easy concept, but if you hear bubbles, you'll be able to feel any big bubbles, so feel them and turn the dive.

 

[PfcAJ]

I agree that there are things that you can sort out without a buddy (like second stage stuff, lp inflator stuff, SPG stuff).

Without a buddy though, you have modes where you shut down the post and you still hear bubbles. Is it a manifold failure or did you shut down the wrong post?

ISOLATE, then reopen the valve you shut down, and try the other.

There's only so many options...