NAVY_MA(Offline)

What I have:
A single AL80 DIR set up. Diving 7mm wet.

What I don’t have:
Enough money to get a double’s setup, or a dry suit.

What I want:
Increased safety through redundancy
Increased bottom time.
Adaptability
DIR compatible configuration
Gear I can Afford

What I’m thinking:

Most of my dives have been shore dives in the 30-70 fsw range, but I would like the ability to dive comfortably in the 70-100 fsw range. There are a variety of wrecks in this range near by, and it would be nice to go a little deeper in the canyons every once in a while. One of the problems I’m running into is that with a conservative rock bottom (amazing what stress will do to your breathing) the 70+ dives are severely limited, not because of the ndl, but because of the amount of working gas I have. Of course I am working on lowering my SAC rate, but that can only take you so far.

I’m looking at adding an AL80 stage to my gear configuration. I think this best fulfills my wants.

-It offers me the redundancy of another first stage.

-It increases my bottom time. (By breathing down the stage to rock bottom, then switching to back gas and breathing that down to rock bottom, I retain my redundancy through out the dive and still increase my working gas by a substantial amount.)

-This rig would be extremely adaptable. If I’m doing a 30fsw shore dive I just strap on my single rig and have fun. If I head out to the Yukon I can add my stage and increase my efficiency and safety on the wreck dive. If I want to do that same 30fsw shore dive but I want to have an incredibly long bottom time, I use the stage. I could go on but you get the idea.

-I believe this rig would meet DIR standards. In fact, I got the idea watching DIR3. It might not fly with GUE standards though…not sure.

-I can afford this. All I need is a reg, a tank, and a stage set up.

What do you think?
Is the set up DIR?
Any safety issues?
Is an AL80 my best choice?
Anything I’m missing?

Don’t worry about my feelings

MonkSeal(Offline)

Don't do it.

No.

Many. Discused several times on this board.

DIR principles. For extending range of diving you should first master the basics (bouyancy, trim, kicks) and lower SAC will come as a consequence. Then you should analyze what type of dive can be conducted - single AL80 with nitrox 32 is quite OK for MDL dives within 30m (100 fsw) range. If you want to exceed this range / level of exposure then you should do some technical training.

Alastair(Offline)

Not ideal but not a complete disaster. I'd prefer a twinset but if I was going somewhere on holiday where I couldn't get one I might do what you are describing.

Not its not DIR, a twinset is much better suited as it has more redudancy options.

The main issue is you are taking more gas but if the stage reg fails you've lost access to it. You also can't share it, if your buddy has an issue - all you can do is hand it over. Out of interest what is your buddy/team doing while you do this? Presumably they will be doing the same? If not how are they managing their gas?

AL80 is probably the best choice in terms of cylinder buoyancy for bottom stages.

Cost is rarely the right reason to make a decision. Personally I'd save and convert it into a twinset. Twin AL80's would be fine in a wetsuit providing weighting is done appropriately. If you've got the regs to do what describe, two AL80's, backplate and harness it sounds like all you need is a manifold and a doubles wing. That sounds like a much better option.

HTH
Al

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gregkeller(Offline)

I'm not sure that this is the best option either, i think wait a little while, save up for what you need to set up your double 80's, it's a lot nicer in the water than a single and a stage.

But it doesn't seem like for these types of dives there is a problem with redundancy and not having enough gas. According to the way the original poster laid out his possible dive profile, he would always have a full "rock bottom" in both of his tanks, so even if one was rendered useless, he would have the other. So lets say minimum gas in an al80 at 100 feet is 1500 psi, then when the stage gets to 1500 psi, he switches to the back tanks, when that gets to 1500 he comes up. To me it seems like anywhere along the way if he has an issue with either of his tanks, he's got enough to get out safely. These are just dives within minimum deco limits.

So the planning sounds kosher, but it's not DIR, and more importantly or maybe the same, there are better ways to skin this cat. Doubles.

TobinGeorge(Offline)

So what? They are still dives. In San Diego you should be able to rent a larger steel single.

Tobin

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lamont(Offline)

X8-130s make great single tanks.

NAVY_MA(Offline)

First, thanks for the responses.

It looks like saving up and going to double’s is the general consensus.

Monkseal:
The nice thing about being a relatively new diver is that I improve every dive. I do work on my base skills at all times, and will continue to do so. Anyway you could point me in the direction of the other threads that discussed the safety issues with this set up? Thanks.

Alastair:
One of my issues is that It seems like I need a singles rig for most of the surf entries I do. I don’t have training on doubles, so correct me if I’m wrong, but they don’t seem well suited for strong surf.
So I can’t justify the cost of going to double’s when the majority of my diving is better suited for a single tank. Yet in the 70-100 fsw range the set up I proposed seems better then a single. Correct?

Out of the two people I regularly dive with. One has money and is going double’s with a dry suit. The other has the same setup as my self (single tank wet) So, I would have no problem with the doubles set up, and could dive single only when I am with the other. (Usually under 70foot diving with her)

I agree that cost is rarely the right reason to make a decision, but that doesn’t mean we don’t all have to make decisions based on cost everyday. But I see what your saying. Maybe saving up for a twin set is the way to go. (I do not have the 2nd tank right now) Thanks!

Gregkeller:

That was my gas planning idea. Leaving min. gas (sorry I like rock bottom better ) in both tanks means I have enough gas to get to the surface in the event that either tank fails.
It seems everyone agrees that double’s would be a better way to go. Being more comfortable in the water is always a plus. Thanks.

Tobingeorge:

Your right they are still dives and I have enjoyed everyone of them. Maybe I’m getting a little overzealous…I seem to do that some times.
As for the steel tank. I have been led to believe that a large steel tank while diving wet is a bad idea. Is that not true? Thanks.

Lamont
That’s a pretty big tank. Thanks for the tip.


For anyone:

Everybody said that the set up would not be DIR. In the dir3 video GI shows this exact set up(with different tank size) as the DIR alternative to a pony bottle. Did something fly over my head (does happen a lot) What makes this non dir?


Again, thank you for your help. I’m just trying to learn. So if I say something ignorant or blasphemes please excuse me!

TobinGeorge(Offline)

In San Diego you will be using pretty thick wetsuits, 5mm minimum 7 mm typical. That will require a far bit of ballast to counter.

The empty buoyancy of a typical al 80 is +4 lbs. The empty buoyancy of most commonly encountered steel tanks is from about neutral to -2.

There are some odd ball steel tanks that are way negative, but not too common, look here Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

That means switching froma al 80 to most steel tanks will result in about 6 lbs less weight on your belt, but very like you will still have 6-10 lbs on a belt even with a SS plate, reg and Steel tank.

As long as you can swim up your rig with a full bottle after ditching what ever ballast you have in a belt there is no reason not to use a steel cylinder.

The "no steels with a wetsuit in the ocean" is much more a problem with negative steel doubles, with a pair of PST 104's you'd likely have no ditchable ballast, and could be ~30-36 lbs negative at depth with near full tanks. That's a real problem if your wing fails.

Tobin

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David Martin(Offline)

A doubles rig (D80's /D12s or similar) will almost certainly be preferable to a single/stage for shore entries. Even when correctly set up a stage will move around far more than the 2nd cylinder on your back.

If you're struggling with wieght etc a single (without a stage) may be easier than a set of doubles, but as soon as you know you want to take two cylinders, a set of doubles is by far the best way to do it.

David

keri.lewis (Online)

When you sit down and think about a single and a stage you will see that it is essentially a set of independent twin tanks... without the nice carrying frame of bands and bolts.

Therefore all the drawbacks of a set of independent twins apply plus the added joy of one bottle swinging around on the stage straps. Unless you have real experience with the moving bottle, the doubles will definitely be easier.

Second point I wanted to look at is cost. In addition to the AL80 bottle..

to use the stage you'd need:

Stage kit
Reg (1st and 2nd stage)
40" hose
6"HP hose
O2 clean gauge
Stage markings etc.

To build a set of doubles:

Manifold
Tank bands
Reg (1st stage only use your octopus from old rig as backup - just swap the faceplates)
22" LP hose
Larger wing (40lb for AL80s is plenty usually.. but I see from your posts you'll do the math.)


I am not sure that (using e-bay judiciously) there is much difference in cost outlay..

If it were me I'd either look at the larger steel bottle to counteract the wetsuit, or a set of Al80 doubles.. which have got to be about the easiest set to dive. I was in AL80s a couple of weeks ago in Asia, and they're so nice to dive.

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Keri

The more I learn.. the more ignorant I realise I am..