Would there be anything wrong to dive independant doubles without a manifold?

[Scubaroo]

An alternative to the doubles is a slung aluminum 40cf or 80cf stage bottle.

 

[MikeFerrara]

SimonN once bubbled...


Kind of, but nowhere near as bad as it sounds. Some people I know breath one tank down until there is enough gas in it for bailout and then swap - that's only one reg swap.

On the rare occasion I dive independents I'll breathe one down to 150bar, swap, breathe the other to 100 bar and then, in theory, would swap again (in theory because I am normally doing deco by that stage, so don't need to swap again). This is 2 swaps.

Interesting, we keep them as even as possible. You never know which one you'll lose. Also when the two are very uneven you notice the weight difference especially when using sidemounted tanks.

Neither is really task loading.

Maybe, but it's more to do.

I said:
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This also effects emergency procedures. Do you have one long hose or two?

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Only people who have never dived independents ask this.

I have only used independents sidemount. I haven't done alot of it but some.

 

[leadweight]

As pointed out above, there are advantages to having a manifold. However, in some locations manifolded doubles are not available or are too difficult to transport. Gadgets (Dive Rite Ultra) that allow a set of independent doubles to be quickly assembled from easily available aluminum 80's can be brought in easily. Apparantly, this technique has been used on a number of expeditions.

 

[metridium]

leadweight wrote...
As pointed out above, there are advantages to having a manifold. However, in some locations manifolded doubles are not available or are too difficult to transport. Gadgets (Dive Rite Ultra) that allow a set of independent doubles to be quickly assembled from easily available aluminum 80's can be brought in easily. Apparantly, this technique has been used on a number of expeditions.

Why not bring a manifold and bands so you could set up doubles on site?

 

[O-ring]

metridium once bubbled...
Why not bring a manifold and bands so you could set up doubles on site?

Do what Scubaroo suggested and sling one of the rental tanks as a stage...

 

[metridium]

O-ring wrote...

Do what Scubaroo suggested and sling one of the rental tanks as a stage...

I must be particularly obtuse this morning, but how is that an improvement over independent doubles? Other than saving a little luggage space, you still have gas management concerns and potential loss of one tank's contents to a bad 1st stage.

 

[O-ring]

metridium once bubbled...
I must be particularly obtuse this morning, but how is that an improvement over independent doubles? Other than saving a little luggage space, you still have gas management concerns and potential loss of one tank's contents to a bad 1st stage.

You aren't obtuse, just not astute today... It isn't an improvement, but would be a hell of a lot easier, IMHO, than rigging them as independent doubles. If using rentals and you need more gas, I think it would be easier (and cheaper) to just get some stage straps and hook one of your stage/deco regs on another rental tank rather than rig them as doubles. Wear one, stage one (or two)...

I'm with leadweight...some places you just don't have access to that kind of stuff and have to improvise.

 

[Scubaroo]

Remember the context the question was asked in - Jackknife only wants to dive doubles maybe ten times a year. Using a slung stage, as long as his current BC has another 3 pounds of spare lift capacity he's not using, he can take 160cf of air along instead of 80cf, and only has to fork out for a stage sling kit (~$40), which takes about 2 minutes with a plain screwdriver to assemble on a rental tank, and the $10 or so for a tank rental. No need to upgrade BCs or wings to one that can accommodate doubles bands, which you would still need with independant doubles.

As he said, it's only for "more bottom time", no overhead penetration, so if he did lose a first stage, he can bail out on the remaining tank.

So at $40 for a kit, and maybe $100 in tank rentals, it's cost him a total of $140 for his 10 "doubles" dives for the year, and he doesn't have to buy a new wing or BC, or independant doubles kit, or manifold. He will need another first stage/second stage/SPG though.

Assuming he has shoulder/hip D-rings to sling the bottle from of course

 

[metridium]

O-ring wrote...
I'm with leadweight...some places you just don't have access to that kind of stuff and have to improvise.

No doubt in extreme cases.

But I don't get why rigging a stage is equivalent or superior to setting up rental tanks using a manifold and bands you brought yourself, if you have that option, as you indicated earlier. It takes me ~15-20 minutes to set up mine, now that I've had a bit of practice. I haven't done any stage diving; is it really that much easier?

Edited to add: Thanks for getting us back on track there, Scubaroo. I definitely see your point.

 

[O-ring]

metridium once bubbled...
No doubt in extreme cases.

But I don't get why rigging a stage is equivalent or superior to setting up rental tanks using a manifold and bands you brought yourself, if you have that option, as you indicated earlier. It takes me ~15-20 minutes to set up mine, now that I've had a bit of practice. I haven't done any stage diving; is it really that much easier?

Banded doubles with iso would be the best choice. I am just thinking what a caribbean dive op would tell me if I walked in and started taking their tanks apart. If you could pull it off, that makes a lot of sense. If not, a little creative staging might be in order.

I have never staged an 80, but 40s disappear underwater..