Moving Doubles Tank Bands When Full?

[Bigeclipse]

All...I dove my doubles for the first time and it was great...although I felt a smudge nose heavy. I have heard that you can move the tank bands as high as basically where the tanks just start to taper to help with trim. The tanks are a good 1.5-2 inches from there as they sit. The problem is I just got them filled. Can you still losen the bands...slide them up and then retighten or should I do it when both tanks are completely emptied? Thanks.

 

[tbone1004]

why did you put them that far down? The standard positioning is to have them right below the crown... It isn't necessarily ideal to do them full, but it will be ok as long as they are laying down and one band stays tight. I'd loosen the upper band and slide it to right at the crown, and tighten, then loosen the bottom, put the backplate on the rig, and tighten the lowers. This is the "standard" positioning of all doubles to my knowledge, so you'll have an easier time adjusting to borrowed or rented tanks

 

[Bigeclipse]

why did you put them that far down? The standard positioning is to have them right below the crown... It isn't necessarily ideal to do them full, but it will be ok as long as they are laying down and one band stays tight. I'd loosen the upper band and slide it to right at the crown, and tighten, then loosen the bottom, put the backplate on the rig, and tighten the lowers. This is the "standard" positioning of all doubles to my knowledge, so you'll have an easier time adjusting to borrowed or rented tanks

They came like that from previous owner so I figured try them where they sit. Thanks for the advice. I really appreciate it. We made two long dives and honestly...it was easy. I even ran the manifold drill with my buddy. I bumped the bottom while shutting the center post so definitely need to practice buoyancy more...etc. this was in 5ft of water fyi so I felt reasonably safe. The second dive we went a bit deeper.

 

[ajduplessis]

During assembly you need to tighten bands and isolator periodically until in the right position. The same holds true in reverse order. When you release bands to move the cylinders, you will also have to adjust the manifold or risk damaging the threads. I would therefore empty the cylinders first, but thats just me.

I suppose you can loosen the bands slightly and tap the bands up or down.

 

[lowviz]

Done it many times.

Just make sure that you only loosen one band at a time, start by moving the top band to right where the neck begins. Tap the band into place with a short piece of wood, 2x4, by sliding the wood along the side of the tank until it catches the band. One hit per side, alternate. When in place, tap the band lightly up and down on each side to make sure that it isn't canted.

There may be a lot of holes in your BP, pick any two that are 11" apart.

-stainless steel galls badly, a little bit of high pressure lithium grease is a very good thing.

 

[Bigeclipse]

Done it many times.

Just make sure that you only loosen one band at a time, start by moving the top band to right where the neck begins. Tap the band into place with a short piece of wood, 2x4, by sliding the wood along the side of the tank until it catches the band. One hit per side, alternate. When in place, tap the band lightly up and down on each side to make sure that it isn't canted.

There may be a lot of holes in your BP, pick any two that are 11" apart.

-stainless steel galls badly, a little bit of high pressure lithium grease is a very good thing.

thanks for the info. With regard to the lithium grease, where exactly are you stating I should apply it? Thanks!

 

[The Chairman]

When you release bands to move the cylinders, you will also have to adjust the manifold or risk damaging the threads

Sry, but this is not true.

If the manifold is adjusted properly, then there's no need to touch it. Loosen the bands as much as you want and gently slide the top up to the beginning of the curve. Tighten it and then use your BP&Wing to space the bottom one. Tighten just a bit and then recheck. As long as it doesn't wander elsewhere, you'll be fine. Just keep checking as you tighten.

 

[boulderjohn]

I have had to adjust them from time to time--it's no problem. Just do what NetDoc says.

The reason some people move them below the crown is a mistaken belief that this will help them reach their valves easier. I did that myself when first starting with doubles, but I soon found right below the crown is best.

 

[rhwestfall]

... and wear your plate in the proper location...

 

[lowviz]

... With regard to the lithium grease, where exactly are you stating I should apply it? ...

Oh, sorry for not being more explicit.

Just a dab on the bolt threads where the nut jams against the band.