Diving Doubles

[TSandM]

Actually, if you are planning to do technical training, I think that getting a set of doubles and diving them for a while before the class is ideal. Such classes, if well taught, are difficult enough, without adding the stress of unfamiliar gear to the mix.

You can dive manifolded doubles as a big single tank (if you haven't learned how to do shutdowns) with the awareness that you have many more failure points, but with the same strategy as singles -- major failure, abort the dive and surface. I swam my doubles around for a few weeks before I tried a valve drill in them.

Do be aware, though, that the danger people are describing is REAL. When you DO start doing valve shutdowns, you WILL almost certainly turn off all your own gas at some point. And when you take your tech training, if you have buddies, it's not at all unlikely that one of THEM will turn off the gas you are breathing at some point. So I would say that, until you are quite facile with the drills AND have proved to yourself that you are calm and methodical when faced with no gas, it's not a good idea to do valve drills without a buddy who is experienced in them, and it's not a good idea to use double tanks for redundancy on solo dives.

 

[Peter Guy]

"Is it necessary to take a class to dive doubles?" -- No, but it might help.

"Are doubles 'too much' for recreational dives?" -- No -- you can never have "too much" gas!

story -- for what it is worth:

I started diving doubles with a mentor who just helped me set up hose routing and gave me some help on trim. (He really thought I'd be a lawn dart the first time but I surprised him.) I just used the doubles as big singles -- that is no valve drills or any idea that I could shut down a valve if there was a problem. It was just for the purpose of getting used to having those big tanks on my back.

I started diving doubles because I intended to do some technical (cave) diving and it made sense to me to get familiar with doubles in OW recreational dives.

Several months later I took Fundamentals in doubles where I was taught valve drills, etc. --but I had trouble with my trim and my instructor was unable to help me out. It took another technical instructor to identify my trim issues (which was actually a BP/W setup issue) and I was able to get my Fundies Tech Pass, Full Cave and Technical Diving cards.

So, go dive doubles, get used to them, take some formal instruction (even if from a mentor make sure he REALLY knows about setup and useage) and have fun.

 

[rongoodman]

They're additional weight and will try to throw you around in the water for a while. As Peter said, they can cause trim problems which require non-obvious solutions. Some people just have trouble reaching their valves, which can end up requiring anything from stretches to a new drysuit and underwear. A good mentor or class will help, but it's going to be some work and expense until you get comfortable with them. They're nice to dive once you get things straightened out.

 

[TSandM]

As Peter said, they can cause trim problems which require non-obvious solutions.

Oh, this is SO true! When Peter first started diving his doubles, he did what most of us did -- ended up in strongly head-up trim. He kept moving weight UP his body, despite me telling him over and over again that he needed to add weight LOW. When he finally did start moving weight down, he was amazed at how his trim corrected itself.

Joe Talavera used to have a LOVELY essay on this on the defunct 5thD-X forum, talking about how too much weight high makes you rear up to shorten the effective lever arm through which the excess weight can act.

You can waste a lot of time trying to solve weight, trim and gear adjustment issues on your own, when a good mentor can fix problems in a few minutes.

 

[a22shady]

Thanks for the repsonses.

I guess some info on my part. I am going to take the class. But I think I will be diving the doubles as single tanks for while untill Everything settles and then will start practicing different drills at platforms.

I already Own Halcyon Eclipse System and Got the Doubles Wing as part of the Package through Halcyon. Already Own the regulators, Guages, Computers, Drysuit, Pony Bottles etc... So I dont really need any new equipement. Other then doubling up on set of individual tanks. More of a reason for the doubles is a concern of My G/F.

On a single HP100 I get a good 2 dives from one tank with no problem. She is usually the one turning the dive because she runs low on air. Which is no problem as the dive is typically over any way. But she has the same feeling as me As we would rather the NDL limit be the limiting factor not how much air is left. Also nice having the advantage of taking little slower as we have the gas to do the dive and spend the avilable time. Then there is the safety factor and risk management that diving with doubles can provide. If a 1st stage malfunctions on a single tank We carry Al 40's so wouldnt be a real issue But with the doubles we could **** down that stage and make our safe ascent saftey stop and exit. Which we can also do with our Pony.

 

[rongoodman]

If you're already diving with slung 40s, I don't see what doubles are going to give you for OW diving. Deeper or with an overhead, soft or hard, is a different story.

 

[BabyDuck]

if your logged dive number under your avatar is accurate - yes, you need to take the class.

i'd say 'slow down & enjoy the journey more', but i've said that before & you don't want to hear that.

 

[a22shady]

i'd say 'slow down & enjoy the journey more', but i've said that before & you don't want to hear that.

I agree with that. That is pretty much why we waited a whole year before taking our AOW class. We purchased all of our gear during OW class (Pool Sessions) And once certified decided to wait and just dive a while get comfortable with our gear and diving and we did. We have around 55 or so dives. But have dove with Pony for about 1/2 of them. Just ready to move up We got the Doubles wing so might as well get to using it.

If you're already diving with slung 40s, I don't see what doubles are going to give you

The Pony is only for emergencies and has no bearing on our dive, As when we have doubles we base our dive on gas in the tanks. So we can have a longer dive and stay within our NDL's where as with singles Our dives would end early because of gas. So diving the doubles we can end our dive becuase of the NDL and not due too lack of gas

 

[PfcAJ]

Have you considered a larger single tank?

Btw, as you dive more, your SAC will decrease, and you'll be doing dives on an al80 that you couldn't do on a lp104 before you know it.

 

[a22shady]

Yea we thought about other tanks But like the Size/Weight of the 100's. but if we did go bigger it would have been either the 119's or 130 but at that point rather just go with 2 100's