tank centering

[minamin13]

I had an issue with listing to one side with my Dive Rite Transpac (no backplate). My husband took video of my backside while I was diving, and the problem became apparent. The tank is obviously angled to one side, preventing the bladder from inflating evenly. Other than tightening the tank straps as tight as possible (I tried doing this and it helped tremendously, but I still felt like it wasn't perfect), is there something else I can do? Another Dive Rite Transpac user recommended a backplate. Are there any light weight backplates that are good for travelling?

Please see video below:

Suck 'Em Up Dive Site, Big Island, Hawaii - YouTube

 

[RickyF]

I would recommend an aluminum backplate with a STA. That will keep it perfectly centered.

 

[Dive Rite]

I had an issue with listing to one side with my Dive Rite Transpac (no backplate). My husband took video of my backside while I was diving, and the problem became apparent. The tank is obviously angled to one side, preventing the bladder from inflating evenly. Other than tightening the tank straps as tight as possible (I tried doing this and it helped tremendously, but I still felt like it wasn't perfect), is there something else I can do? Another Dive Rite Transpac user recommended a backplate. Are there any light weight backplates that are good for travelling?

Please see video below:

Suck 'Em Up Dive Site, Big Island, Hawaii - YouTube

Hi Minamin,

Sounds like a weight placement issue. The TransPac works well with single tank, especially. It's hard to trouble shoot without knowing more about your rig, exposure protection, etc. If you can, give us a shout at 800-495-1046 and we can help get you sorted. I would not recommend buying an aluminum plate and STA unless you prefer to change rigs for other reasons.

Thanks,
Kathleen

 

[minamin13]

It's not a weight placement issue. I checked to make sure that weights were even on both sides.

I was wearing a 3 mm wetsuit, and I was wearing 3 lbs on either side of my BCD. From the video, the tank does not appear centered, and the bladder is not inflating uniformly.

 

[DA Aquamaster]

Your backside looks fine but your wing is a little bit more inflated on the right than it is on the left.

If it happens all the time it is worth looking into, if you just noticed in the video, it may have just been an isolated event or due to other things. For example, if you roll to the left all the time to look at your buddy on the right, air may migrate to the right and stay there given the slight taco effect of a single tank wing.

I agree with DR that the tank is not really the problem. If you are not convinced take 2 pieces of 1/2" or 3/4" PVC pipe just long enough to extend past your cam straps and connect them with cave line threaded through holes in the pipe above and below each cam strap. If the pipe is tied in that manner with proper spacing just last the cam band slots, you'll create an inexpensive and light weight STA that will help you confirm or disconfirm the problem.

If that works for you, you can make it a more permanent STA by taking some heavy nylon fabric and sewing two tubes to hold the PVC and the cut and bind the edges of the 4 slots needed to accommodate the cam bands to create an inexpensive and light weight STA for less than $5.

 

[fnfalman]

With the Transpac, the tank cannot be mounted lopsided.

It looks to me that the air could have trapped one side more than other (it does happen even with so called donut wing). You deal with it by shifting your body a bit to make sure that the air bubble would redistribute itself.

However, my humble opinion is that maybe you overtightened one shoulder strap more than the other. That will throw your rig out of balance. I've seen it before. Hell, I've done it before.

 

[minamin13]

I just returned from diving in Monterey, CA and the mystery deepens.

I normally don't list to the side with cold water diving, because I dive with a drysuit, and only use my drysuit for buoyancy control. The listing started to occur in Hawaii, which lead me to believe the BCD was the issue.

But now I'm not so sure. I started listing to the left in Monterey, too. Later on I learned that there was a tiny bit of air in my BCD. But I definitely don't think it is due to the shoulderstraps because I completely loosened them up to their full extent. Ah well, maybe I'll try my pool to troubleshoot some more.

I am aware of the technique of centering my air bubble. In fact you see me doing so in my video just as I reach the sky light in order to fill the deflated left side of the bladder.

 

[fnfalman]

So, you loosen your shoulder pull straps all the way? Sounds like the harness might be too small for you.

There's no reason why a Transpac would be heavy on one side if proper weight distribution (lights, reels, SMB, dive weights, trim weights, et al) isn't an issue.

 

[lsorenson]

I put a STA on my wife's transpac and it works really well... It stiffens the harness up and helps with placing on the tank... I like this setup myself...

lee