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Use of lift bag when bc fails

Discussion in 'Basic Scuba' started by fisherdvm, Sep 1, 2018.

  1. aquacat8

    aquacat8 Solo Diver

    # of Dives: 100 - 199
    Location: Savannah, GA
    1,505
    1,146
    I need help, it’s fine to self teach some stuff but that rapid ascent scared me.
     
  2. aquacat8

    aquacat8 Solo Diver

    # of Dives: 100 - 199
    Location: Savannah, GA
    1,505
    1,146
    In my experiments with weight and buoyancy I have found that of the two, buoyancy is the harder to deal with.
     
  3. fisherdvm

    fisherdvm Solo Diver

    # of Dives: 200 - 499
    Location:
    3,577
    47
    It is hard to remember, but my tanks are all steel. 80 cu ft, - 8 lbs. 120 cu ft - 11 lbs. doubled that us - 16 lbs and - 22 lbs full. I guess before one dive wetsuit with double steels - try to swim with 22 lbs of bricks then do it with your wetsuit. They say wetsuits lose 1/2 to 1/3 of their buoyancy at depth so that might not help you much on the bottom. When I dove dry, or with full 7mm and a 7 mm shorty on top, I needed 20 lbs lead. So it might be ok to dive steel up north.
     
  4. The Chairman

    The Chairman Chairman of the Board Staff Member

    # of Dives: I just don't log dives
    Location: Cave Country!
    62,376
    30,972
    Physics says. The buoyancy in your wetsuit comes from entrained air. At 33 ft you have half the buoyancy. At 99 ft you have 1/4 of the buoyancy. "They" have nothing to do with it. :D :D :D

    There's a workshop on the 22nd at Blue Grotto and the Fall Megadive is just around the corner. I'll be glad to show you the "lines". :D :D :D
     
    aquacat8 likes this.
  5. aquacat8

    aquacat8 Solo Diver

    # of Dives: 100 - 199
    Location: Savannah, GA
    1,505
    1,146
    Thanks Pete, I am planning on coming to the Megadive!
     
  6. Landlocked123

    Landlocked123 Contributor

    # of Dives: 200 - 499
    Location: Reisterstown, MD
    448
    125
    I carry 2 smb's.. One SMB in a DIY jerry - rigged PVC carrier strapped to my backplate. Due to how I spiral roll the bc in there I am able to, with one tug, deploy it , and watch it as it unfolds like a rug. I am then able to inflate it. The process takes about 18 seconds on average. I practice it ever third dive or so. The issue with SMB's is that most ways of carrying them involve multiple steps, un clipping (potential to drop it), get wrapped up in it, etc... the method I devised works unbelievably well. Whatever method you use for carrying your secondary lift capability make sure its easily deploy able and practice.
     
    AfterDark likes this.
  7. fisherdvm

    fisherdvm Solo Diver

    # of Dives: 200 - 499
    Location:
    3,577
    47
    Finally got to use a small 25 lbs lift bag at 80 ft. It worked well, as long as you grabbed it high below the bubble to facilitate the opening of the relief valve. I think it would be difficult but not impossible to maintain a 15 ft safety stop. I will have to try that, hoovering and maintaining a safety stop with this smaller bag. The larger just did not work.
     
  8. fisherdvm

    fisherdvm Solo Diver

    # of Dives: 200 - 499
    Location:
    3,577
    47
    I think the safer option is shoot a large smb or bag from depth and winching yourself up. I see plenty of steel doubles in 3 mm wetsuits in Florida. I have asked a few about their back up plan, and they all have said reel and bag.
     
  9. Snoweman

    Snoweman Contributor

    # of Dives: 100 - 199
    Location: Atlanta, GA
    4,559
    3,624
    Did you have to tie your spool to the end of the line? Or, is it already tied? I've never pulled all the string off of mine. Too lazy.

    Also, back in August I posted about practicing so not to get entangled. I was basically told I was a doofus by another member and that "it ain't rocket science". Thank you for your posting.

    BTW, @aquacat8, I shot mine at about 15-20' and got it tangled with my octo/inflator hose combo. I know what you mean about it scaring the hell out of you (me). I'm just glad I wasn't at 45', where I now, carefully, deploy it. I did give the DM a good laugh, though.
     
    aquacat8 likes this.
  10. fisherdvm

    fisherdvm Solo Diver

    # of Dives: 200 - 499
    Location:
    3,577
    47
    I seem to keep a tight short line when I inflate. I usually do it about 25 ft, as the inertia to launch a large burst of air will pull me up a few feet.
    The momentum to move me allows almost 1/2 of the sausage to fill, and I winch myself up slightly negative. Then fill rest of tube from below the water. If you want the sausage to stand straight up, dump more air out. But no so much that you would sink. I think this works best for the larger sausages.
     

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