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Camera Buoyancy

Discussion in 'Tips and Techniques' started by KelvinW, Nov 19, 2019.

  1. KelvinW

    KelvinW Garibaldi

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    So what do you guys think about the buoyancy you need to aim for?
    like how close to neutral is close? 10g? 50g? 100g? 200g?

    My current rig dry weight 4kg.
    -With lens A in fresh water is around 1030g
    -With lens B in fresh water is around 880g

    So I was thinking to get
    A) 1x400g (8cm x 5" Carbon Fiber) + 1x600g (8cm x 8" Carbon Fiber) for each arm. which is close to 1030g in saltwater. (might be imbalance sideways). if using lens B, put 3x50g fishing weight on a zip ties on 600g side.

    B) 1x 800g (8cm x 10" Carbon Fiber) above the body. and just bear the 150g-200g. Assuming your phone weight 180g and a 7" tablet weight 330g. and you are holding with both hands. Then there's less stuff to carry during travel.

    So how close to neutral do you think the best?

    Other than that, I'm not even sure how much I should trust the listing.
    8cm x 10" Carbon Fiber
    Some listing +600g, same size said +800g, another one +900g, another one said it was +1.2kg.
     
  2. kelemvor

    kelemvor Big Fleshy Monster ScubaBoard Supporter

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  3. jgttrey

    jgttrey ScubaBoard Supporter ScubaBoard Supporter

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    Location: Houston
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    I'd try to stay balanced if I could. Unbalanced rigs suck.

    IMHO, you want to be slightly negative so that the housing drops away from you, slowly, to hang on a tether if you need to drop it or have it out of the way. That's preferable, for me, to having it float up and be in the way when I'm switching gasses, on deco or dealing with something else.

    Are you using strobes? If so, Option B doesn't make sense to me vs. using two 400gr CF arms.

    Assuming the numbers are all accurate, I'd go for 800 gr of buoyancy, preferably in the form of 2X 400 gr. CF arms. When I dove with the heavier lens A rig, I'd use some closed cell foam on the housing or port to add a little more lift. You're not far off.
     
    KelvinW likes this.
  4. KelvinW

    KelvinW Garibaldi

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    Yup, 2 strobes that's weight 330gr in freshwater.
    I guess it's better to get 2x600gr CF arms, and just add 4x50g fishing weight. and finetune with 20g weights.

    So another question is. How much is "slightly?" between 0-50gr? or 50gr-100gr from neutral? I read somewhere said between 0.5 to 1 lbs.
     
  5. jgttrey

    jgttrey ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
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    Don't know that I've ever measured it, but I would say no more negative than you need to, well, make it negative. You don't want to sink like a rock, just hang down instead of float up.

    I assembled my rig and put it the pool hanging from a string and scale and went from there in picking my arms. I didn't bother to repeat after I got them since it felt fine, which was all that mattered.

    My sense is that .5-1lb is too much and that just a few ounces negative would be ideal.
     
  6. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

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    Agreed. 200g max negative. Also, you don't want to have to change your weight belt depending on whether you take the camera or not.

    My system uses 2 CF arms plus a few STIX pieces....balanced L and R. It is barely negative with my lightest lens/port and tolerably negative with my heaviest. It can all be done with a luggage scale and a large tub.
     
  7. jgttrey

    jgttrey ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
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    p.s. If you need to add a smidge of weight to make it negative, you can probably find something more useful that a fishing weight, like a double ended boltsnap or something. If you're going to add weight, make it something that you might need in a pinch. But, it should be possible to avoid needing to add weight at all.
     
  8. Chris Ross

    Chris Ross Barracuda

    # of Dives: 200 - 499
    Location: Sydney Australia
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    100 gr or so negative is not a problem, you don't want it positive I took the wrong combo one dive and had the housing maximum 100 gr positive, it was very difficult to work with. If you have a dome that will be lightest point and want to twist up if the rig is overall positive.
     
  9. KelvinW

    KelvinW Garibaldi

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    I was thinking to tie zipties on both end of the tray, and attach these as needed. if I don't need some, I can probably put the excess weight to another zipties tied to the belt.
     

    Attached Files:

  10. JackConnick

    JackConnick Optical Ocean Sales ScubaBoard Business Sponsor ScubaBoard Supporter

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    You might want to check out our Kraken Adjustable float arms. You can let water in with a push button to trim it. It unscrews to empty.

    KRK-Adj-Float-Arm-1.jpg
     

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