Using back mount doubles as single tanks

[rob.mwpropane]

That's the most visually beautiful set of doubles I've ever seen. Love the colors and decals. But man that's weird compared to what I dive.

It's funny you say that... I had to look at the picture for a minute to make sure it wasn't CGI, lol

 

[RyanT]

And if "righty tighty, lefty loosey" is etched in your DNA, wait till you get in a shower that has valves with reversed threads! I was standing there getting scalded...with ever growing panic because my ingrained brain wouldn't allow me to turn the valve the other way to shut the water off! LOL!

 

[rob.mwpropane]

And if "righty tighty, lefty loosey" is etched in your DNA, wait till you get in a shower that has valves with reversed threads! I was standing there getting scalded...with ever growing panic because my ingrained brain wouldn't allow me to turn the valve the other way to shut the water off! LOL!

I thought that's why we're taught to "test" new showers with a hand before you just jump right in? Did you really think the assless chaps would protect you?

 

[RyanT]

What I did learn is that some plumbers have a twisted sense of humor! LOL!

 

[rx7diver]

So any reason I could not use doubles as if they are individual tanks IE no manifold?

Absolutely you can! Excellent configuration for solo diving, IMHO. Alternate breathing off each cylinder, though, in such a way that you can always end the dive breathing off only a single cylinder if you have to.

I am a big fan of independent doubles.

rx7diver

 

[Angelo Farina]

That's the most visually beautiful set of doubles I've ever seen.

Technisub, the best.
Founded by J. Cousteau and his friend Luigi Ferraro, who was the CEO.
However the Technisub RAID tank used by Cousteau was even nicer.
See here:

Love the colors and decals.

The decals say "15 years warranty", as these were the first alu tanks sold in Italy.
Made by Luxfer.
They were supposed to be life-long lasting. Later we discovered that this is not really true...

Does this not use bands?

No.

Is it just held together with the manifold and oversized boot?

Yes. The boot is NOT oversized, it was made of a special technopolymer. Actually it is much thinner and lighter than the rubber boot used in competing twin tanks by Cressi, Mares, Scubapro, etc.
Being very light, it had a slot for inserting an optional 2 kg lead weight, for better balancing.

How does it attach to the harness/plate?

The tanks have their own harness. It was designed to be used with no BCD, or a horse-shoe BCD.
However, when the first back-mounted wings appeared in 1978, the plastic plate was attached very simply with two short stainless screws passing through two holes in the plate and being screwed in a plastic cylinder, having a 3 cm diameter, which was placed in the gap between the two tanks. Simple and neat.

What are the clamp-on cones around the tank necks, weights?

These are spring-rotable attachments for the shoulder straps of the harness. Another patent of Ferraro. This way the spring keeps the strap tilted towards the center of the chest, but when donning or doffing the tank, the spring gives up, rotating externally and allowing an easier operation.
Here you see a detail of these spring- rotable shoulder strap attachments:

Does that center post rotate?

Yes, of course. Another patent here, even pressurised at 200 bars the central valve was rotating smoothly, as the air pressure was loading a teflon washer instead of the dynamic O-rings.
Also the reserve knob is patented: a spring brings it back up if the rod is inadvertidely pulled before the set pressure (100 bars) is reached.
This impedes to start diving with the reserve valve already open, or to pull inadvertidely the rod during the dive, before the reserve pressure is reached.

 

[VikingDives]

If I was going to back mount doubles, and I'm not, I would only consider doing it with independent doubles since I can't reach my left valve to shut it down, but I could shut down my left valve with my right hand (damn you rotator cuff!).

Then I'd have to ask myself what advantage I'd get vs sidemount and my answer won't be "None I can see." So I'd just dive sidemount.

 

[MB NZ]

Another advantage of independent cylinders is that you can swap one cylinder out after a dive if using soft cam bands.

I know it's not a popular configuration, but it provides more gas and redundancy than a single cylinder and more gas than a single plus pony.

 

[-JD-]

If I was going to back mount doubles, and I'm not, I would only consider doing it with independent doubles since I can't reach my left valve to shut it down, but I could shut down my left valve with my right hand (damn you rotator cuff!).

Then I'd have to ask myself what advantage I'd get vs sidemount and my answer won't be "None I can see." So I'd just dive sidemount.

Yep. Getting old sucks. That left, LH valve is a PITA to reach. A standard valve on the left or the isolator is no problem for me.

BM is more straight-forward in a typical dive boat situation. And unless you are going to Don and Doff in the water it is probably easier from a ladder and deck-navigation perspective.

Absolutely you can! Excellent configuration for solo diving, IMHO. Alternate breathing off each cylinder, though, in such a way that you can always end the dive on a single cylinder if you have to.

I am a big fan of independent doubles.

rx7diver

Another advantage of independent cylinders is that you can swap one cylinder out after a dive if using soft cam bands.

I know it's not a popular configuration, but it provides more gas and redundancy than a single cylinder and more gas than a single plus pony.

I custom re-machined my backplate to support single, banded-double, or independent-double setups (singles and IDs with only cambands required - no adapters or STA). On the Coz Invasion I had more usable gas and redundancy without having to bring (and coordinate filling) a pony by renting an extra tank and using 3-tanks across a 2-dive trip. The upcharge for (2) 100s would cost the same as the extra 80.

 

[rx7diver]

If I was going to back mount doubles, and I'm not, I would only consider doing it with independent doubles since I can't reach my left valve to shut it down, but I could shut down my left valve with my right hand (damn you rotator cuff!). ...

Do a search for @Akimbo's inverted back-mounted manifolded doubles. Neat! I suppose inverted independent doubles (IID) would be just as neat. Keeps your chest free of clutter, and easier on people with rotator cuff issues (probably), both!

My OMS (Faber) LP46's are pretty short for me. (I am 6'2".) At one time a while ago I considered IID-ing these.

rx7diver