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Please evaluate my weight calculation, Buoyancy

Discussion in 'Buoyancy Compensators (BC's) and Weight Systems' started by rnln, Feb 26, 2020.

  1. rnln

    rnln Nassau Grouper

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    Previously, I went with back inflate BCD, and the jacket BCD before. Now, I am ready with my BP/W. This will be the first dive with BP/W for me. Can experienced help evaluate my plan on weight below?

    I am 5'9", 200lbs on average day.

    I used back inflate BCD, 7mm farmer John wetsuit, AL80 tank, 30lbs weight. I could get down ok.

    With jacket BCD, 7mm farmer John wetsuit, AL80 tank, 32lbs weight. I really had hard time to get down. The dive master had to help pulling me down a bit to initiate the descenting. Still, I had hard time staying down there.

    Now, I have BP/W. Base on the back inflate with 30lbs of weights:
    OMS stainless steal back plate, DSS single wing: - 7lbs
    5mm wetsuit, non-farmer John: - 4lbs

    30 - 7 - 4 = 19lbs. Should I try 19lbs? Or should I start with 20lbs to make sure can get down, rather a little heavier than lighter?

    Thank in advance.
     
  2. saxman242

    saxman242 Manta Ray

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    Always better to be too heavy than too light. I'd start at 22 lbs and see where you're at.
     
  3. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
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    Nothing beats the weight check at your SS and the slow, controlled ascent to the surface. I dive a back inflate, with an AL80, I use 14 pounds with a full 5 mm +/- a 5/3 mm hooded vest. You did not give your size, I'm about 5'10". 185 pounds. 20 pounds sounds like it may be a place to start. Really, 7 pounds from a back inflate to a BP&W? I dive a SP Knighthawk. Better to be a little heavy than too light
     
    hammet likes this.
  4. Erik Forsberg

    Erik Forsberg Sea Corgi

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    If you can't get down with a full tank, you won't be able to hold a safety stop.

    Add 5lbs at least first or to your buoyancy check with a bear empty tank.
     
  5. rnln

    rnln Nassau Grouper

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    Sorry, I missed my size. I just added it.
    I took 7lbs off for the DSS SS back plate, and 4lbs to go from 7mm farmer john to 5mm 2 pieces.
     
  6. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    11,942
    7,666
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    Sorry, I may have missed it, is your BP&W with a steel or AL backplate? That may have been my problem.
     
  7. rnln

    rnln Nassau Grouper

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    I never wear a BP/W. This will be my first time, it will be SS, DSS. I have worn jacket and back inflate BCD.
     
  8. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    11,942
    7,666
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    The SS backplate certainly explains some of the weight change, thanks
     
  9. martincohn

    martincohn Solo Diver

    # of Dives: I just don't log dives
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    Its too important to "think" you have it right. Test it!
    1. Get a tank with 500 PSI and test your buoyancy. Can you hold a safety stop?
    2. Yes, great you passed your buoyancy test.
    3. No, adjust and repeat until you do.
    Its too simple of a task to risk not getting it right. And the potential complications of an uncontrolled assent definitely aren't worth it.
     
    BHWookie likes this.
  10. rnln

    rnln Nassau Grouper

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    Thanks everyone,
     

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