input on an issue with an oversized wing

[txaggie08]

At least I'm assuming this may be my problem. I was, until recently, not diving with a suit. Since adding the suit, my buoyancy has been...hit or miss, especially shallow. I understand fully the concept of compression, but this seems to be a little odd.

I'm finding myself, at times, fighting to maintain buoyancy near the end of a tank AT TIMES. This is not a consistent phenomenon, but rather seems to be about 40-50% of the time. I'm leaning towards the idea that the wing is to large, and is trapping air. I'm also being forced to go vertical and vent from my inflator rather than a butt dump the majority of the time in order to vent properly with very little air in the wing. I've actually started carrying a little more weight than I normally would just to allow more air to stay in the wing...


It's a halcyon 40# wing with SS backplate and weighted STA. I carry about 4# more than that in my pockets on a typical fw dive. Saltwater weighting has been very hit and miss.....the last time I dove in cozumel also was the first time I dove with a suit, and when the problems I seem to be having started.

I'm curious if moving to a 30# or even 20# wing might not solve some of my air trapping and venting problems? I have ~35 dives on this rig, only the last 12 or so have been problematic, but then again I'm slightly over weighted with the STA and SS plate anyway with no suit.

 

[DevonDiver]

Were talking single-tank diving here, right?

 

[txaggie08]

Yes, just single tank. Its the 40# singles wing. I'm planning to start with doubles eventually,but still on 1tank

 

[DevonDiver]

I used to use a 40lb Eclipse wing in the UK - diving a large (15L) steel cylinder, with steel pony, heavyweight can-torch etc. I didn't find the same problems. Since I moved to the tropics, that down-sized to a 30lb (Halcyon), then a 17lb (Oxycheq) wing...

The only air needed inside a wing is to compensate for exposure suit compression and unconsumed gas in the cylinder. Everything else is solved through effective weighting and equipment choice.

Buoyancy fluctuations in the shallows is an issue caused by surplus gas in the wing. It may be possible that the wing isn't dumping effectively, but making sure excess gas isn't necessary in the wing in the first instance addresses cause, rather than symptom.

An 'over-size' wing can 'taco'... making it harder to quickly dump the air. Assuming you're using a single tank wing (Eclipse, not Evolve) it's a donut design, without bungees... and should be easy to control air migration using effective trim. Just make sure that you're getting your OPV/LPI into the highest position, so that air will migrate there, before dumping.

When using the OPV (rear dump), the position of the valve will sometimes leave a little air remaining above it. You need to dump whilst 'gripping' around the wing itself, with a twisting motion. Hard to describe, easy to do. Kinda like 'wringing out' the wing and twisting the OPV into the uppermost position.

 

[g1138]

To clarify, you're having inconsistent problems with being positively buoyant at the end of your dive only when you're wearing an exposure suit, and you think an oversized wing may be the cause?

What thickness suit are you wearing, what tank, and how much lead are you wearing total?
Are you experiencing a halocline during some dives?
Have you tried tilting your butt to one side to get the butt dump at the highest point?