Where to place bands on doubles?

[Campana]

I've used a few sets of doubles, but have one new set and am borrowing one set for Fla. My 94's that I've been using seem awful short next to the 104's (borrowed) and the 108's (my new ones). I know to put the bands 11" apart, but I don't know where to place the cylinders in the bands "up and down" wise. Obviously, I may have to move them up or down if I find they throw off my trim, but where would you start? My 94's seem to have about 7" above the top band and about 7" below the bottom band. This is not an exact measurement, but is a rough measurement for discussion purposes.

Would it make sense to keep the ratio the same with the other sets, like the same amount of tank above the bands and below the bands?

Sign me:

Baffled

 

[Divesherpa]

I would recommend putting the bands as close to the valves as possible. This means putting them where the tank remains a constant diameter, but barely.
Works for me, but everyone's different.

 

[roakey]

Ditto divesherpa,

The top band goes right where the cylinder's shoulder meets the cylinder body. That'll keep all your valves in the same place when you reach for them.

Roak

 

[Uncle Pug]

I agree with Sherp...
I have 3" bands and they are all the way to the top...
Just before the tank starts to curve...

 

[D.I.R.Lizard]

Yep I have to agree with everyone else, I dive 104's with Highlad Mills bands(3" I believe) and I always put them right below the tapered part at the top.

That is the way I was first shown how to do it and it works great at least for me. Just my opinion

 

[roakey]

Baffled,

In case you haven't found this page on Jim Cobb's site:

http://www.cisatlantic.com/trimix/doubles/doubles.htm

Roak

 

[padiscubapro]

Originally posted by roakey
Ditto divesherpa,

The top band goes right where the cylinder's shoulder meets the cylinder body. That'll keep all your valves in the same place when you reach for them.

Roak

I can't fully agree with you..
I believe its a good starting point but the main issue is being able to operate the valves IN THE WATER.. Remeber all valves including the isolator.
Start with the bands as others have suggested, check that you can reach them while in gear if you cant reach them at this point you woun't be able to reach them in the water unless your can move around within your harness, then go in the water and try to operate the valves,it will be hardest on the surface since you will be vertical (I bring this into consideration since you may not be in the prone position when a failure occurs and I'd rather not waste any time if I'm having a major gas loss) and the tanks tend to move away from yor back, decend and try to reach them, if you cant reach them lower them on the tank, this will raise the vales with respect to the diver. Take care in not moving the valves too high since you will then probably hit your head on the isolator. Once you know the distance on 1 type of tank just measure the distance from the valve knob to the bands and regardless of tank size or valve design if you duplicate this distance (FOR YOU) you should always have the tanks placed optimally for you.

 

[MikeFerrara]

Yes. Trim must be correct and you must be able to quickly reach the valves. One without the other is no good. If the tanks must be so high as to mess up trim in order to reach the valves you need to find and address the cause. IMO, its best to adjust trim with tank position and avoid adding things like ankle weights. I am refering here to lp doubles where you normally would not need to add any weight.

 

[padiscubapro]

Originally posted by MikeFerrara
Yes. Trim must be correct and you must be able to quickly reach the valves. One without the other is no good. If the tanks must be so high as to mess up trim in order to reach the valves you need to find and address the cause. IMO, its best to adjust trim with tank position and avoid adding things like ankle weights. I am refering here to lp doubles where you normally would not need to add any weight.

I agree, I should have added the trim part... My main point is that there really is no correct position for everyone..

 

[Divesherpa]

I concur with PSPro on this point of experimentation. I experimented and concluded to put the bands as high as possible because I slam my head into the crossover