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Thistlegorm tank turn off!

Discussion in 'Near Misses & Lessons Learned' started by Herbiehamshank, Jul 31, 2010.

  1. Herbiehamshank

    Herbiehamshank Registered

    # of Dives: 100 - 199
    Location: Isle of Man
    Thistlegorm tank turn off!


    Just thought i would share with you an incident i experienced last month whilst diving the Thistlegorm in Egypt. My buddy and i were returning to the boat after the dive. I had 70 bar and dive had gone fine. We were doing our safety stop at 5 metres where there was also a spare tank attached to the line by a rope ( in case anyone comes up short on air). After doing the full 3 minute safety stop i moved up the line to go to the surface. Unforrtunately the rope from the spare tank snagged on my tank and i tried several times to shrug my way free. Eventually my buddy unsnagged me and i moved off to complete the last 5 metres to the top. After 1 metre my air just stopped suddenly. As i only had the last 4 metres and my buddy was still below me i made it up to the surface with no real problem. Back on the boat we were trying to work out what happened as i knew i definitely had plenty of air. We went through the scene and then the penny dropped! He reached for my valve and turned it- straight back up to 70 bar. In my struggle to free myself from the rope, i must have caught the tap on the rope and the shrugging motion must have turned the tank off. I had definitely fully turned it on with a single turn back as is standard. What a relief that the very thing that was there to save me hadnt ended up killing me. We all talked about this on the way back, and didnt think either of us did anythin wrong, but put it down as one of those things. next time i get tangled however, i will always check i still have air before moving away from my buddy at all!
  2. fisheater

    fisheater Divemaster Candidate

    # of Dives: 200 - 499
    Location: Sebastopol, CA
    When you found yourself entangled and your buddy was nearby, you should have froze and signaled your buddy to free you.

    Around here in the kelp, your buddy is your first option for disentanglement. Trying to free yourself often leads to further entanglement or other, unexpected issues, so it's the second choice.
  3. TSandM

    TSandM Missed and loved by many. Rest in Peace ScubaBoard Supporter

    I got this lesson in my first dive with Andrew Georgitsis. I got too close to the upline and he tangled me up in it. He put my buddy out of gas, and I donated and put my backup in my mouth (diving doubles) and slurp! no gas. He had rolled off the left post for me. Lesson learned -- if you get tangled in ANYTHING, your valves are at risk. I'm glad to hear this happened to you so shallow that it was largely a non-event. Had it happened just off the deck of the Thistlegorm, I think you'd wish your buddy had been closer at hand :)
  4. openmindOW

    openmindOW HSA Instructor

    Herbie, thank you for posting. It's a good lesson. It could happen to anyone. Thanks for sharing.
  5. Hetland

    Hetland Solo Diver

    # of Dives: 500 - 999
    Location: Gulf of Mexico
    Happened to me without entanglement. I was at the surface moving among the safety and travel lines of a charter boat and one of them somehow turned off my valve (I sucked my last breath at about 4ft during descent, switched to my backup 2nd, and found it empty as well) I returned to the surface, and it took us a few moments to figure it out. The dive master not only remembered checking my tank, but remembered me checking it again after he did. Not a pleasant experience.
  6. RJP

    RJP Scuba Media & Publications

    # of Dives: 1,000 - 2,499
    Location: New Jersey
    Thanks for sharing your story. However, I gotta tell ya, I have a hard time believing that the tank was fully opened. Think about how many turns of the valve would be required to take a valve that was fully opened and turn it fully closed. It is more than "several" which is how many times you say you shrugged to get free.

    Possible? I suppose. But I think the more likely scenario is that the "single turn back" when you thought you turned the tank ON was actually a single turn on when you actually turned the tank OFF.
  7. Damselfish

    Damselfish Solo Diver

    # of Dives: 1,000 - 2,499
    Location: Boston
    lots of people don't consider a "single turn back" as standard anymore. There may have been some physical reason to do this with old valves that does not apply anymore. So the single turn back may do nothing but cause potential confusion as to whether the valve is almost open or almost closed.
  8. Hetland

    Hetland Solo Diver

    # of Dives: 500 - 999
    Location: Gulf of Mexico
    Happened to me. I have never practiced the single turn back procedure. My valve is always 100% open. Additionally, I was at the surface for several minutes while other divers descended the line. I was breathing fine at and near the surface. It wasn't until I made my way further up the line and then descended that my reg locked up.

    BTW, your valve does not have to be 100% off for it not to deliver air.
  9. battles2a5

    battles2a5 Divemaster

    # of Dives: 200 - 499
    Location: Charlotte, North Carolina
    A few tips to keep this from happening again:

    1- Don't let anybody touch your valve, especially when you are getting ready to hop off the boat. I always ask the mates/DM's on a mixed boat not to check my valves
    2- Practice valve shut-downs. This is mandatory when you move to doubles, but also useful on singles. Breathing down a shut-down valve is a pretty unique feeling, so you should know exactly what it is when it happens and you should be proficient at manipulating the valve(s) behind you.
    3- Get in the habit of doing a flow check- again, more applicable to doubles in overhead environments but any time you make contact with something behind/above you, reach back and check your valves.
  10. InTheDrink

    InTheDrink DIR Practitioner

    # of Dives: 1,000 - 2,499
    Location: UK, South Coast
    You clearly have an issue with this valve fully open or valve fully closed business.

    I'm with you on this 110%. The quarter turn back is simply a route to confusion.

    Your tank should be fully on or fully off. Anything in between is, over time, asking for trouble.

    Do the popular agencies still teach the quarter turn back?? Is it scheduled for decommission? It seems like one of those things that should clearly be put out of its misery...


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