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Weight and Trim

Discussion in 'Hogarthian Diving' started by lairdb, Sep 10, 2004.

  1. lairdb

    lairdb Solo Diver

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    Weight and Trim diary, chapter MMMCMLXXVI; the Continuing Story of getting my rig Dialed In, Submitted in the Hopes that it might be Useful to Others:

    I have been fairly happy with where I have settled a while back -- I have an SS backplate, used almost invariably with an AL80, banded directly to the plate (i.e. no STA. If more of my diving were local, rather than travel, I might consider an STA, but 6# of plate is quite enough to pack.)

    I also have, at the rearmost possible position of the waistbelt(next to the plate), one on each side, small XS Scuba pockets. When I wear only the 3mm fullsuit, I put 2# each (4# total, plus the 6# plate); when I add the 3mm "core warmer", I add another 2# to each pocket (8# total, plus the 6# plate.)

    I do not have a can light, but I hang a bellows pocket on the right, where a can light traditionally goes, filled with a pound or so of junk, plus 1 or 2 slightly negative backup lights (more non-DIRness: light 1 and light 2.) I also usually am carrying a camera (1# or so negative), though I wasn't last evening for this experiment.

    Last evening's experiment was to see if I could move the weight from the small pouches on my waist straps, to small pouches on my lower tank band.

    Positives of doing so: removes clutter from waist area, possible trim improvement.
    Negatives: becomes harder to ditch (fairly minor -- I'm not a believer in ditching); possible interference with wing inflation.

    Unknown: effect on trim.

    Experiment outcome: sucked. I was genuinely unsure what the effect would be, and I could imagine CofM models that went either to improved trim and stability, or worsened.

    I positioned trim pouches (identical to the others) as close to the plate as possible, on the lower tank strap, one on each side. I loaded them with the same 4# each I would otherwise put in the waist pouches. They did not seem to materially interfere with the wing inflation.

    As we back-swam out to the descent point, I did not immediately put together the nice stable boat-with-keel feeling I had during the backswim, with the conclusion I shuld have reached -- I was now very tank-heavy, and on descending, found it nearly impossible to keep from spinning along my long axis and doing a convincing imitation of a flipped-over junebug on the ocean floor, arms and legs wiggling in the "air" as I struggled to turn tank-up.

    (Fortunately for my dignity, conditions were fairly murky and my buddies distracted by the profusion of lobsters, so my junebug imitation went fairly un-noticed.)

    Interestingly, I perceived that by the time I had consumed about 1200 pounds (taking the tank to 1500; my buddy had gotten a hot fill), the situation was much better. While some of this was, no doubt, the refinement of my anti-junebug skills, I'm guessing that some of it was buoyancy change in the tank (1200psi =~3 pounds of change.) From this, I'm guessing that, despite the initial pronounced junebug effect, it wasn't too far off.

    This leads me to think that I might be successful with 4# on the waist, and 4# on the lower tank strap. However, this doesn't allow me to entirely remove the pouches from the waist, so it's a less attractive solution.

    --Laird
     
  2. kelseysmith

    kelseysmith Divemaster Candidate

    # of Dives: 50 - 99
    Location:
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    How about this: http://www.deepseasupply.com/page8.html

    It would be nice to be able to keep the trim pockets out of the picture entirely

    Kelsey
     
  3. lairdb

    lairdb Solo Diver

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    Agreed -- in fact, reducing the trim pocket's interference factor was the original intent of the experiment. However, with 90% of my diving being travel, I'm unwilling to carry additional weight.

    If I were, I'd probably add an STA and p-weight, and solve the problem that way.
     
  4. kelseysmith

    kelseysmith Divemaster Candidate

    # of Dives: 50 - 99
    Location:
    33
    0
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    Another possibility might be to mount the same pockets to the plate somehow.

    Not really sure how much work you feel like, (drilling stainless is a pain I have heard) but it might be possible to drill and tap the plate, and use Stainless screws to mount the pockets to the plate on either side of the channel.

    That way you would maintain the flexibilty of the pockets and still keep the belt free. should also minimize the balancing issues you described.

    Hmmm. this is sounding like a discussion for the DIY forum not the Hog forum.

    I'll be quiet now :blush

    Kelsey
     
  5. lairdb

    lairdb Solo Diver

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    Oh, don't stop floating ideas -- that's how we make progress. Free and open exchange, etc.

    I thought about that, but it's fairly hassle-y (drilling SS and all that.) Also have mentally doodled with somehow attaching the pockets to the continuous webbing where it passes through the plate... somehow.
     
  6. The Kraken

    The Kraken He Who Glows in the Dark Waters (ADVISOR) ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Roswell/Alpharetta, GA
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    For trim purposes, I've added a 5# trim weight pouch to both the upper and lower tank straps; one pouch is positioned on the right side of the tank and the other on the left.

    If I need extra weight it's distributed rather evenly along the tank and equally on opposite sides.
     
  7. cool_hardware52

    cool_hardware52 Dive Equipment Manufacturer

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    What lead to our bolt on plate weights was a friend who was using #4 Sausage weights on each side of his plate. He was using clipping the weights to the perimeter holes on each side. He would remove them for doubles.

    Actually worked ok except the weights would swing a bit. He preferred this approach to a heavy STA as that tended to move the center of mass to far above his back when horizontal.

    If I was using the sausage weights I think I'd add a couple zip ties in middle to reduce the swing.


    Regards,



    Tobin
     
  8. lairdb

    lairdb Solo Diver

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    Thanks, Tobin; good background; the plate weights or sausage solution works for home, but I'm already packing more weight than I want to for travel -- I'm still in search of a solution that yields better trim and allows me to use destination-borrowed lead.

    For home-area diving, I'm thinking about fabbing "micro-P-weights"; 2 of them at 4# each, that I can just drop into the plate-wing hardware stack.
     
  9. cool_hardware52

    cool_hardware52 Dive Equipment Manufacturer

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    Sounds like a winner.



    Tobin
     

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