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Escaping Down Drafts

Discussion in 'Basic Scuba Discussions' started by lermontov, Apr 7, 2016.

  1. Kevrumbo

    Kevrumbo Banned

    # of Dives: 1,000 - 2,499
    Location: South Santa Monica Bay/Los Angeles California, USA
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    Here's a harrowing encounter with open water downcurrents, for a group of tech divers on doubles with what would seem to be plenty of breathing gas margin, and less dense "easy breathing" 18/45 trimix with a deep MOD (67m @ PO2 1.4) margin to fight or ride out a strong downdraft:

    It turned out to be very treacherous encounter indeed --even as a planned technical dive prepared for & expecting currents as they did. . .
     
    Last edited: Apr 8, 2016
    kr2y5, VsubT and chillyinCanada like this.
  2. PeterNBiddle

    PeterNBiddle Manta Ray

    # of Dives: 100 - 199
    Location: Seattle, WA USA
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    Covered in depth here: current

    Here's the original post, but there's more in the thread that's also worth reading, including other accounts from other divers on the same dive:

     
    Last edited: Apr 8, 2016
  3. chillyinCanada

    chillyinCanada Solo Diver Staff Member

    20,626
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    Wow. Scary.

    My experience was in Maldives. We weren't on the wall, it was a bad drop. Trying to fight our way forward in the oncoming current is when I realized what was happening. I felt fortunate that while it was a down current, it wasn't shoving us deep, though we were exceeding MOD. Those above us didn't seem to be affected. It took a few minutes to get sorted, especially getting my buddy's attention, all the while wondering if we'd get an oxtox hit.

    I've no advice. We were in an open patch and we swam diagonally up and forward. No idea where we'd have ended up otherwise.

    The currents in Maldives are ridiculous. I think I'm over that place. :)
     
    Dizzi Lizzi and PeterNBiddle like this.
  4. CuzzA

    CuzzA Solo Diver

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    Scary stuff, especially if you're not on a wall. I don't believe it has been mentioned and I failed to include it in my original post, but if you can't seem to halt the descent I think it's probably wise to dumb weights as well. I realize there's a high risk of injury from a rapid ascent, but I'd rather be rescued on the surface rather than recovered on the bottom or never recovered at all.
     
    Last edited: Apr 8, 2016
  5. Dhboner

    Dhboner DIR Practitioner

    # of Dives: I just don't log dives
    Location: Toronto
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    Although I have never encountered a down current I have a personal rule that I won't dive any Nitrox mix on a dive where the hard bottom exceeds the MOD unless I have two independent buoyancy systems. Don't flame me, it is a personal decision, but on wetsuit dives along a wall where a loss of lift can potentially send me below the MOD of my back gas and ruin my day I dive air only. If I am dealing with a loss of buoyancy or a down current I don't need to add an O2 tox to my growing list of concerns.
     
    Last edited: Apr 8, 2016
  6. TMHeimer

    TMHeimer Divemaster

    # of Dives: 500 - 999
    Location: Dartmouth,NS,Canada(Eastern Passage-Atlantic)
    13,002
    3,100
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    Dhboner, No reason for any flaming here. Though I rarely dive nitrox, this is exactly how I think.
     
    Dhboner likes this.
  7. BCSGratefulDiver

    BCSGratefulDiver Mental toss flycoon ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: On the Fun Side of Trump's Wall
    75,463
    61,426
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    How do you guys manage to dive walls that have a hard bottom below recreational depths? Some of the walls in places like Bunaken, Maldives, T&C, and even Cozumel extend well below ranges that would be safe on any breathing gas ...

    ... Bob (Grateful Diver)
     
    chillyinCanada and Dhboner like this.
  8. OldPhotog

    OldPhotog Angel Fish

    # of Dives: 50 - 99
    Location: Nashville, TN
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    Thanks for that. It seems like a good guideline/rule to adopt.
     
    Dhboner likes this.
  9. lermontov

    lermontov Manta Ray

    # of Dives: 500 - 999
    Location: christchurch
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    someone posted they take a pony with air to switch if they exceed MOD but i think its probably better to either avoid the area or stay on air not EAN- swapping bottles on a down draft is over taxing
     
    Dhboner likes this.
  10. chillyinCanada

    chillyinCanada Solo Diver Staff Member

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    Those of you limiting yourself to hard bottoms and air, may need to get out more and expand your diving horizons.
     
    mmmbelows, Diving Dubai and BRT like this.

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