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Question about Fixing the Tank to BC

Discussion in 'Sidemount Diving' started by Miko_T, Jul 17, 2019.

  1. Miko_T

    Miko_T Garibaldi

    # of Dives: 25 - 49
    Location: Toronto
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    Hi, I am planning to do my sidemount course in September and I am learning the configuration of BC now. I have a question about fixing the tank to the BC.

    I saw sidemount divers fixed the bottom of the tank at the butt plate with a bolt snap and fixed the top of the tank near the chest with a bungee. But when we do giant strike, we need to use a bolt snap to fix the top of the tank at the chest D-ring before we go into the water.

    My question is why using a bungee? Why can't we just use two bolt snaps to fix both end of the tank, one at the chest D-ring and one at the waist D-ring? I think it's easier to access the tank underwater in emergency situation and more stable than using a bungee. Thanks in advance!
     
  2. racanichou

    racanichou Manta Ray

    # of Dives: 50 - 99
    Location: Toronto, Canada
    829
    309
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    The bungee will bring the tank higher and closer to your body. The bolt snap won’t.
    As for giant stride, you will put your elbows on top of your valve to prevent them from hitting you. I add a bolt snap with the bungee on a chocked for that entry.
     
    Miko_T and Rollin Bonz like this.
  3. Rollin Bonz

    Rollin Bonz Solo Diver

    # of Dives: 200 - 499
    Location: Georgia, the state, not the country ;-)
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    Exactly. Bolt snaps only in the water and the top of the tank is going to be all over the place. Bungees keep them nice and snug and stable.

    Just my take...

    Bolt snaps help with out of the water support. Bungees can't properly support the tank weight out of the water (or during giant stride entry). While you're in the water before exiting, slip the tanks out of the bungees and allow the bolt snaps to support the tanks. Trying to get the tank out of the bungees otherwise can be difficult.

    They can also provide a back up connection in water in case the tank slips out of the bungee or the bungee fails.
     
    Miko_T and racanichou like this.
  4. ScubaWithTurk

    ScubaWithTurk Bubble Blowing Buddha

    # of Dives: 200 - 499
    Location: Al Ain, Abu Dhabi, UAE
    640
    410
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    Yes, the burgess keep the cylinders closer to the body and in a steady position rather than moving all over the place.

    As for getting them off to get back on a boat, here is my process:

    I release my bungees on the safety stop and clean up the hoses. I start by switching to my backup, undo the right cylinder (long hose) bungee, stow the hose and reg and clip onto the chest `D-ring.

    Then I take the bungee off the left cylinder, pull the reg out and take the bungee backup over my head and put reg back in. At this point I clip to the chest D-ring.

    Once the stop is done I slowly ascend in horizontal trim, unclipping the right cylinder from the rear AP. Then unclip the left from the AP. Once at the surface I only have two clips to release to hand both cylinders up to the Captain.
     
    racanichou and Mike1967 like this.
  5. Subcooled

    Subcooled Assistant Instructor

    # of Dives: 200 - 499
    Location: Finland
    951
    229
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    No, we do not.

    Some people want to use a bolt snap on dry land (instead of a flexing bungee) but if the tanks are small and light, then there is no need, and if the tanks are larger then they can be supported by your arm. If you intend to walk or climb inside a cave for a long distance then maybe you will want that clip (because supporting the tank for an hour would suck).

    The bungee cord will pull the cylinder up. With bolt snaps it will be angled at -30 degrees.
     
  6. Mike1967

    Mike1967 Manta Ray

    # of Dives: 50 - 99
    Location: Victoria, Australia
    665
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    Until your bungee snaps and you smash a reg.
     
    racanichou likes this.
  7. racanichou

    racanichou Manta Ray

    # of Dives: 50 - 99
    Location: Toronto, Canada
    829
    309
    63
    Bungee for in water or just about to splash.
    Double ender for everything else. Simple, elegant, and safe.
     
  8. Zef

    Zef Divemaster

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    Or use Dive Rite Nomad ring bungee loops. The bungee extends from the plate/sidemount bc to a 2inch diameter stainless steel ring that has a bolt snap connected to it via quicklink. The bolt snap on at the top of the tank is held in place to the neck of the tank with a choker and that bolt snap is clipped to the stainless steel ring. The bolt snap on the bungee loop is clipped to a shoulder/chest d-ring. When on land or when splashing the tank is supported with metal to metal contact and when in horizontal diving position the tank is pulled up and into the body in a streamlined position. The position of the ring more or less determines where the tank will hang and can be adjusted for individual preferece

    I don't sidemount (yet) but have adopted this for use with my pony bottle....I took 6mm bungee, passed one end through the stainless steel ring, and threaded the 2 ends through a hole in the edge of my backplate and knotted the ends in an overhand knot,, adjusting the length to get the ring to sit where I want. I have a quick link between the ring and the bolt snap. I put second d-ring on the left shoulder strap of my harness to attach the bolt snap...this keeps my upper left d-ring unencumbered for clipping of my torch or anything else.



    -Z
     
  9. racanichou

    racanichou Manta Ray

    # of Dives: 50 - 99
    Location: Toronto, Canada
    829
    309
    63
    That tank is hanging way too low with that ring. No way you can get it up and under the armpit.
     
  10. ScubaWithTurk

    ScubaWithTurk Bubble Blowing Buddha

    # of Dives: 200 - 499
    Location: Al Ain, Abu Dhabi, UAE
    640
    410
    63
    Agreed which is the downside of the ring bungee system. I am actually shocked anyone uses that these days as loop bungees have been shown to hold the cylinders in better positioning.
     
    racanichou and Mike1967 like this.

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