Too much of a Good Thing

I have developed (of all things) a SEVERE head-down trim condition in my single-tank cavern rig while running shallow…

Givens:
95 steel with H-valve
Stainless steel b/p
DR Venture Cell
Wreck Canister, right belt mount
3# lead in Clipper pocket, left belt mount (to counter roll from battery)

I was diving a VERY old 3/3 combo, and trim was a tad head down but acceptable; now diving a 5mil one-piece, and find it difficult to NOT assume dancing on head posture when 20’ or shallower…also, unstable in roll axis (wanting to invert until past 20’)

Suspicions:
The new suit has moved the CB down towards legs…
The small size of the cell prevents the CB from moving “up” relative to CG of tank until sufficient gas is input…
Shorter tank moves CG forward towards shoulders, acerbated by s/s BP (I noted LESS problems with an AL80)…

Possible fixes:
Ally b/p (moves CG aft)…this would unfortunately mean I had to carry more lead…
Traditional wing (Trek is next size up)…this would move CB aft, but in a single tank, I fear the dreaded “Taco shell” config…
Ankle weights…UGH!

Do any of the fine-trimmed Readers here have other ideas/comments?

Thanks!
Norm

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Originally Posted by normblitch

Do any of the fine-trimmed Readers here have other ideas/comments?

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Sounds like you've got most of the ideas covered. You might consider adding a neoprene vest or vest+hood combination to any of the other ideas which might shift CB higher while also adding warmth to the toso area. A little violence with a pair of shears on your old combo upper might provide something suitable at little or no cost (shearing the arms short/loose especially to keep mobility).

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Originally Posted by Gary

Quote:

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Originally Posted by normblitch

Do any of the fine-trimmed Readers here have other ideas/comments?

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Sounds like you've got most of the ideas covered. You might consider adding a neoprene vest or vest+hood combination to any of the other ideas which might shift CB higher while also adding warmth to the toso area. A little violence with a pair of shears on your old combo upper might provide something suitable at little or no cost (shearing the arms short/loose especially to keep mobility).

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Good Idea! Will shop for vest soonest...Thanks!!

(BTW, steelie is ALREADY as low as it can go on the b/p)

Norm

Norm,
-do you use jetfins (they are heavier)?
-you may try to restrict lower part of aircell with bands
- there are special small trim weight pockets that you can place on shoulder straps or onto tank upper (lower in your case) camband
- wing won't do a "taco" if you link it to the plate using existing or sewn tabs (steel links or cave line may be used)
- did you eat carrots before dive? Then make 3-4 holes in crotch area :-)
How was your pony bottle plonge, did take any nice pics last weekend?

If you're not using Jetfins (or equivalent), try those. They're much heavier than crappy plastic fins and they form a nice counterweight when in a horizontal position.

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Originally Posted by ARY

Norm,
-do you use jetfins (they are heavier)?
-you may try to restrict lower part of aircell with bands
- there are special small trim weight pockets that you can place on shoulder straps or onto tank upper (lower in your case) camband
- wing won't do a "taco" if you link it to the plate using existing or sewn tabs (steel links or cave line may be used)
- did you eat carrots before dive? Then make 3-4 holes in crotch area :-)
How was your pony bottle plonge, did take any nice pics last weekend?

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Ary,

I'm using Lamar's DiveRites...they are sinkers, but don't know how they compare to Jets...Bev has a pair, and that may be something to try...also, I still haven't tried the Fara II's yet...AFAIR, they WERE sinkers!!

trim in Cam band is food for thought...

"Capturing" wing on b/p...like Trek mods for sidemount??

Carrots, NO...Breakfast Burrito of Death a possibility...beware of brown bubbles...<g>

Survived pony OK under Tom's watchful eye...
seen at http://www.pbase.com/eanx/ginnie4305 ...

Norm

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Originally Posted by DRE

If you're not using Jetfins (or equivalent), try those. They're much heavier than crappy plastic fins and they form a nice counterweight when in a horizontal position.

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Dre,

Heavier fins ARE a more attractive option than ankle weights...more Science Projects for Ginnie Saturday...Thanks!

Norm

As simple as it sounds, I corrected the same problem by letting my shoulder straps out a couple of inches, which drops the whole rig down toward the (picture forrest gump here ;o) buttocks. No extra weight, no silly golf swing fixes, just about an inch of back plate at the cleft of the nates.

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Originally Posted by divindoubles

As simple as it sounds, I corrected the same problem by letting my shoulder straps out a couple of inches, which drops the whole rig down toward the (picture forrest gump here ;o) buttocks. No extra weight, no silly golf swing fixes, just about an inch of back plate at the cleft of the nates.

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Now THIS sounds elegant...I'm assuming that the crotch strap is then snugged up in reaction to avoid ride-up?

Norm

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Originally Posted by normblitch

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Originally Posted by divindoubles

As simple as it sounds, I corrected the same problem by letting my shoulder straps out a couple of inches, which drops the whole rig down toward the (picture forrest gump here ;o) buttocks. No extra weight, no silly golf swing fixes, just about an inch of back plate at the cleft of the nates.

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Now THIS sounds elegant...I'm assuming that the crotch strap is then snugged up in reaction to avoid ride-up?

Norm

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I personally would not recommend this - once the harness is properly adjusted it should be left alone. Shoulder straps that are sliding all over the place are a CF.
One other question I have for you is how much do you arch your back? When you keep your back straight, it'll usually push your head down; however, if you arch your back it'll push your head. While it may seem somewhat uncomfortable at first, your muscles will get used to it.