Wing trim roll issue

[Rick Inman]

Well, I now have 26 dives in my new PB/wing setup, and I'm having an issue I need to correct. Here's my setup:
Fred T 12# BP with STA, Oxycheq wing, 8# of weight in 2 pockets (4# on each hip on harness), 8# on weight belt evenly distributed, Faber steel LP95 tank, 2 13cf pony bottles (argon and bailout air) mounted on each side on tank (I know, I know, but lets assume for now the ponys are here to stay).
Here's the issue. To dump air from the wing I need to roll a bit right, but when I do am spun over on my back. Any twisting at all to the right or left tries to send me rolling over onto my back. I moved my weight pockets to the front and moved my weight belt weight to the front and this helped, but only a little. The weight from my BP and tank still tries to roll me onto my back. Any suggestions?

 

[simbrooks]

Is this oxycheq wing a horseshoe or donut (also dont know if single or hybrid or double wing to fit this combo of tanks)? Is this the cause of you needing to roll so far to your right? If a horseshoe wing, can the air not get over there also by raising your head/shoulders and then dropping head down whilst raising left side - might not need as much roll in that case and not have the same moment arm. Personally i only use a tiny amount of the 34# lift i have in my wing - i have the steel tanks on order.

Could you mount your little bottles more as stages on your left side (or one on each side) - countering the roll over affect. Obviously you have a lot of weight on your back and that is the lever arm that is forcing you over when the centre of gravity goes to the side of your centre of buoyancy - thus flipping you. It just seems that having one main tank and two little tanks would be too heavy on your back (doubles would seem to be slightly different as one is countering the other a bit in balance) and far off your back to give you this kind of moment to spin you.

Also is the STA weighted? It would seem you have 12+2(to 6)+ tank weight on your back and 16# on your front countering that roll. There is far more on your back and nice and high up than there is countering. Water doesnt hold shear and therefore you just slide thru it under the torque. Moving those little tanks down might help to counter the effect of the main tank moment, whether they are both on your left side or one each side.

 

[Boogie711]

Rick - I'm sure you know what you're doing, but I count at least 35 lbs of weight there! Could that not be part of the problem??!?!?!

Here's where I'm getting that:
12# backplate
8# weightbelt
8# pocket
5 # equivalent weight (going from AL80 to LP95)
2# STA

When I dive dry with a single steel LP95 on my back, I have 9 lbs on my belt and 12 lbs combined BP and STA. And I'm a big guy, at 6'4", 225 lbs. (Or, using my own calculations, the equivalent of 26 lbs.) If I dive wet with a 7mm, I dump 3 lbs from that.

The other thing to consider is that I don't dip to my right to dump air with my Oxycheq wing, I dip down. In other words, just sort of lift your butt end. No need to roll around.

Finally, it sounds like your centre of gravity may be too far off your back. Can you get a lower profile STA?

Just some thoughts, anyway.

 

[LioKai]

I agree with Boogie.

Are you able to use the bp/w WITHOUT the STA? This will put the tank closer to your back, effectively lowering your center of gravity.

By eliminating your STA you will move your tank as much as a couple of inches closer to your back. This is why I went to the flat back plate from JetHarness. The Jet puts the tank at 1/4" off my spine. Be sure to set your tank straps as high on the tank as possible incase the first stage and valve are hitting you in the back of your head.

Also, are you able to mount the two pony bottles any closer to your body. In other words not as far out to the sides.

Last, your lead weight sounds very excessive. Even in a larger dry suit.

Good luck and happy diving.
Matthew J D'Avella

 

[Rick Inman]

Is this oxycheq wing a horseshoe or donut

Donut.

Could you mount your little bottles more as stages...
Also is the STA weighted?

Stages, good idea! STA is the 2 piece, non-weighted.

Rick - I'm sure you know what you're doing, but I count at least 35 lbs of weight there! Could that not be part of the problem??!?!?!

Wrong on the first, right on the second. Ponies are AL, so not sure what that's doing weight wise. The undies that came with the drysuit are thick, so I always run a little heavy, but yes, I need to reduce weight. Yesterday, between dive one and two, I kept the extra weight and moved it forward hoping to counteract the rear weight of tank/BP. I know I can lose 4 pounds at least and then I'll be even more rear heavy (like my 3rd grade teacher).

The other thing to consider is that I don't dip to my right to dump air with my Oxycheq wing, I dip down. In other words, just sort of lift your butt end. No need to roll around.

Really? Doesn't dipping down send the air to the bottom of the wing? The bottom dump faces toward the diver, so you can't dump from that. This sounds like it would help, can you explain?

Finally, it sounds like your centre of gravity may be too far off your back. Can you get a lower profile STA?

I can lower the STA on the BP by dropping it to the next lower set of holes. Sounds like it's worth a try.

 

[Rick Inman]

Are you able to use the bp/w WITHOUT the STA?
Also, are you able to mount the two pony bottles any closer to your body. In other words not as far out to the sides.

Don't know about loosing the STA, but the pony mounts DO stick the ponys out an extra 2 inches on each side of the main tank.
BTW, just got back from Kona 3 weeks ago. Made 18 dives in 10 days - 14 beach, 4 boat.
You lucky dog...

 

[simbrooks]

Ponies are AL, so not sure what that's doing weight wise.

If they are full or empty then they are negative (slightly) according to Luxfer:
Tank=S13S Pressure=3000psi Size=13.2cuft Outer Dia=4.38in Length=13.1in Empty Weight=6.0# Buoyancy (Full)=-1.71# Buoyancy (Half)=-1.21# Buoyancy (Empty)=-0.72#

So along with all the other weight you are wearing, these are another few pounds each, but not much. Having those where you have them, is more weight at the same kind of lever arm and helps, putting them forward might help somewhat and be in place of some of that you moved in your pockets and weightbelt.

The undies that came with the drysuit are thick, so I always run a little heavy, but yes, I need to reduce weight. Really?

I dont know enough about drysuit diving, so cant really comment, but it doesnt sound like a lot of weight.

Doesn't dipping down send the air to the bottom of the wing? The bottom dump faces toward the diver, so you can't dump from that. This sounds like it would help, can you explain?

The bottom of the wing is where the rear dump it, as the wing curls up when there is air in it the dump facing the diver is on the outside of the wing (facing away from your tank out to your side) and so the air that is forced down there by you doing a head down maneover (sp?) will all be able to go out of that dump at the bottom left side of your wing. Try it sometime, particulary with a donut wing you dont have to get the air to go around the top, it can flow in from both sides to the rear end.

 

[MikeFerrara]

Really? Doesn't dipping down send the air to the bottom of the wing? The bottom dump faces toward the diver, so you can't dump from that. This sounds like it would help, can you explain?

The wing will wrap around the tank so the pull dump faces to the side and maybe up a little. Just raise your butt a little to dump from the rear or arch your back a little to dump from the inflator.

Of course if you have too much weight on your back it'll still want to turn you turtle if you give it a chance.

 

[detroit diver]

Donut.

..............

Really? Doesn't dipping down send the air to the bottom of the wing? The bottom dump faces toward the diver, so you can't dump from that. This sounds like it would help, can you explain?
........

Yes, the air goes to the bottom of the wing, which because you dipped down is now the top of the wing! (That's not meant to mean you stand on your head!). The dump facing toward the diver is irrelevant-it will dump just fine in that position. No need to roll left or right to dump air.

It does sound like you are a bit overweighted though.

 

[Rick Inman]

I'll give it all a try tomorrow night on my next dive. Thanks all.