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My BP/W rolls me on my back!

Discussion in 'Buoyancy Compensators (BC's) and Weight Systems' started by Crazy Fingers, Feb 25, 2007.

  1. Crazy Fingers

    Crazy Fingers Barracuda

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    I seem to have a little problem with my setup. It's a 35 lb singles wing with a 6 lb SS backplate. I am diving an aluminum 80 right now in a 2 mil shorty and no additional weights. When I stop swimming, I will begin to list one direction or the other until all of a sudden I just roll over onto my back.

    I cannot see anything about my weight that is unsymmetric (i.e., cam buckles are centered.) This occured while the tank was 2/3 full so it was still a little negative. It tended to roll me towards my left side but would also roll right if I went over that way a little.

    I can keep it horizontal with just a little effort while stopped by resisting the listing with my torso, but it still bugs me. Is there a technique to avoiding it, or is it just something I'm going to have to deal with?
     
  2. elmo6s

    elmo6s Instructor, Scuba

    # of Dives: 500 - 999
    Location: New York
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    Maybe you have gas :) - Strange though...
     
  3. rakkis

    rakkis ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: Southern California
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    You probably need to adjust the webbing. The plate is not evenly centered
     
  4. cool_hardware52

    cool_hardware52 Dive Equipment Manufacturer

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    This is actually quite typical. There will be point in your dive where you have very little air in your wing, and your bottle may still be negative. That means you have mass above your CG. That's inherently unstable.

    How to cure? Practice helps a bunch, and here's one tip that helped me. Assuming a horizontal diver with knees bent ~90 degrees. Keep your fin blades horizontal and your feet wide apart. Do not keep your feet together.

    With your fins horizontal and wide apart it's really easy to resist the overturning moment with just the slightest fin movement.

    With your feet together you can't resist.

    Try it, after a few dives it will become second nature.

    Tobin
     
  5. dumpsterDiver

    dumpsterDiver Banned

    # of Dives: 2,500 - 4,999
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    Or you could do the obvious thing and eliminate the source of the problem: Ditch the stainless plate and wear a weight belt on the front of your hips. This will eliminate the inherent instability in a BP/W with a heavy steel plate.
     
  6. RICHinNC

    RICHinNC Solo Diver

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    That is one way...but a little drastic in my book. I have an SS and found that I have better trim by pushing my weights as far back until they hit the plate on either side. It also helps me stay stable when I surface and eliminate the "fall on the face" syndrome some have with a bp and wing.

    For me a belt would not work. I have no hips and keeping it on would require rope!

    Plus...I have a 13 cuft pony on my cam bands on my right side yet I am still stable and experience no roll.
     
  7. Charlie99

    Charlie99 Solo Diver

    # of Dives: 500 - 999
    Location: Silicon Valley, CA / New Bedford, MA / Kihei, Maui
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    I have the same problem with a 5 pound plate, AL80, and 5mm wetsuit. Only happens when shallow. At depth, with a bit of air in the wing, the setup is stable in the face down position (but not all that stable at intermediate positions such as 45 degree roll). When shallow, the plate wants to take me to a horizontal, but face up, position.

    I temporarily solved the problem by adding some weight to my belly side, even though I was then overweighted a bit.

    An aluminum plate is probably the best solution if you want to stay with BP/W, AL80 and little or no neoprene.
     
  8. dumpsterDiver

    dumpsterDiver Banned

    # of Dives: 2,500 - 4,999
    Location:
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    If the guy has zero weights, then he can not reposition weights. The situation of using a stainless plate and zero weight Will (as explained very well by others) result in an unstable equilibrium. To reduce the instability, the ONLY methods is to lower the center of mass and raise the center of bouyancy, so that the later is above the former. Same as a sailboat has a heavy keel BELOW the bouyant hull. I try to position lead on my waist so that it is as far forward as practical and I use an aluminum plate.
     
  9. Firefyter

    Firefyter Solo Diver

    # of Dives:
    Location: NE Texas
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    I can tell you from experience that Tobin is right as usual. It's amazing how much better my frog kick got after I switched to BP/W :D
     
  10. *Floater*

    *Floater* Solo Diver

    # of Dives: 100 - 199
    Location: Here, there and everywhere
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    I also experienced the same thing on my first few dives because I didn't realize to balance out the wing (I was overweighted too). At some points during the dive I'd end up with more gas on one side of the wing than the other, which I wouldn't notice when swimming because movement kept me in trim, but then when I stopped I'd start to tilt. To stop it you need to shift some gas to the side that tilting down, this becomes automatic after a while and you won't even notice it.

    If you are tilting head down or up rather than sideways, then you probably need to change your weighting (move some of it up or down) and also to use your feet position to stay trimmed out (push them out to shift your center of balance downwards and vice versa - assuming your fins are neutral or negative).
     

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