Question Realistic to use same set of Steel 12s for backmount AND sidemount?

[Cheizz]

There possibly is diving in my future that involves both backmount doubles (North Sea wrecks for example, diving from a high freeboard boat with a crane/lift to get divers out of the water, probably in some swell too) and sidemount diving as well.

Suppose I get a nice twinset of steel 12L tanks. If I remove the metal bands and the manifold and plug the manifold holes, I have two steel tanks perfect for sidemount diving, right?

How easy is it to put the twinset back together? Just a matter of installing the manifold and metal bands again? Any risks involved that I'm not aware of?

 

[Wibble]

Yes. But you have to empty them to convert from/to sidemount to/from backmount

Actually, the concave "Euro 12s" are fantastic for backmount as they'd a little tail heavy. The rounded bottoms on Euro 12s are better for sidemounting as the weight's more evenly distributed.

The best sidemount tins I've ever had are the 8.5 litre long steel tanks. Sort of like 7's but a few inches longer. They're fantastic in the water and with 17 litres have plenty of volume. They can be overfilled to give more volume.

Where's your sidemount diving going to be?

Backmount off a boat and doing decompression dives is great. Sidemount with decompression stages can be a little fiddly -- perfectly doable, but not so comfortable.

 

[SlugLife]

Suppose I get a nice twinset of steel 12L tanks. If I remove the metal bands and the manifold and plug the manifold holes, I have two steel tanks perfect for sidemount diving, right?

yes.

How easy is it to put the twinset back together? Just a matter of installing the manifold and metal bands again? Any risks involved that I'm not aware of?

That's relatively correct. It might be a little annoying to do on a regular basis, but it's not rocket-science. And the tanks will be empty every time you swap them.

Around where I am (USA, TX) at least one of the local scuba-shops that does fills will refuse to fill an empty tank. They'll want the tank to go through another $20 "VIP" inspection (which many think those inspections are a fraud). I don't know how many shops are like that locally, or if that's a thing you'll run into in the netherlands.

Something I've done after swapping a valve, is to use another tank and a transfill-whip to bring my tank up to about 400 psi (27.5 bar), before bringing it to a shop for a fill.

 

[rongoodman]

It's doable, but probably more trouble than it's worth. It might be easier to borrow or rent a pair of singles and set them up for sidemount when you need them. (You'd still have to empty one if you wanted a left-hand valve on it.) Repeatedly removing and rethreading the manifold would just be asking for damage to the fine threads.

 

[happy-diver]

An instructor told me recently that diving 15l manifolded tanks from a boat with a lift is safer than diving12s

 

[Cheizz]

All good points. The over-use of the fine thread and the tanks needing to be empty for the swap, triggering extra inspections or problems getting them filled. Food for thought.

 

[Wibble]

Keep an eye out for second hand cylinders. Must add the price of a test.

You'll soon see your cylinder collection grow!

 

[happy-diver]

Actually I said that just now, what she said was that cliched BS that nobody ever died from carrying too much air

Translation is she thinks me a big guy diving manifolded 7l is too small but I'm the diver and my back thanks me

An instructor told me recently that diving 15l manifolded tanks from a boat with a lift is safer than diving12s

 

[Cheizz]

Keep an eye out for second hand cylinders. Must add the price of a test.

You'll soon see your cylinder collection grow!

Have bought all my cylinders second-hand. I now have two (slightly different) 12L, one 10L and one 15L, all steel. I think about getting a D12 and then putting a long stem left and right valve on the two separate 12Ls, so they're good for sidemount as well. Or maybe get a second 10L and sidemount with those...

 

[Wibble]

Actually I said that just now, what she said was that cliched BS that nobody ever died from carrying too much air

But how many got a hernia from lifting the things on their back!