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Old dive accident: 2001 student diver in Lake George, NY

Discussion in 'Accidents & Incidents' started by Ryebrye, Sep 23, 2020.

  1. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
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    Regarding this story, I would say the reporting was pretty good compared to most such reports, but there is still not enough information to know what happened. The story said that the deceased diver panicked for an unknown reason, let go of the ascent line, and drowned. I can speculate a number of reasons that might have happened, but the important things is that when she let go of the rope, she descended, meaning she was negatively buoyant. This means it could be one of those cases in which dropping weights might have helped, but she should not have been in that situation to begin with, and if he was panicking, she would not likely drop the weights. During the ascent, she should have been roughly neutrally buoyant, in which case descending would indicate she was already helpless. She was probably negatively buoyant and pulling herself up by the rope, which is not good technique.

    What follows is sheer speculation based on what I have seen in similar situations. It may have absolutely nothing to do with this actual case, but perhaps readers might find it helpful.

    In dive instruction, students usually do hours of training in a swimming pool prior to going into the open water environment. They are often dressed in 3mm suits or less. (The dive shop with which I am somewhat associated is now using a pool so warm that they are not using wetsuits at all.) As they practice ascents, there is little change in buoyancy. Many instructors teach an incorrect ascent technique that is commonly used in warm water diving. They teach students to dump ALL their air from their BCDs prior to beginning the ascent. They should instead teach them to begin the ascent while neutrally buoyant and dump a little air at a time as they ascend so that they maintain control. In a swimming pool with a 3mm suit, the difference is negligible.

    If they then go to a site like Lake George and use a 7mm suit (or worse, the typical 7mm two-piece common then), it is a whole different world. Because a 7mm suit loses buoyancy so rapidly upon descent, a diver needs much more weight to descend than is needed during the dive. Thus, at depth, anyone in a 7mm suit is overweighted, and dumping ALL the air out of the BCD may make it impossible for the diver to ascend without help--as by pulling on an ascent line. Letting go of the line will lead to an immediate descent.

    Ascending with a thick wetsuit takes practice for a beginning diver. You must begin the ascent neutrally buoyant and dump air in little burps as you ascend. The wetsuit will become more buoyant especially in the last 15 feet, so you have to be careful to avoid a rocket ride to the surface. You don't want that, but neither do you want a plummet to the bottom. My first cool water diving was as a DM assisting classes while wearing a 2-piece 7mm suit. My job was to swim around the class doing their skills in shallow water to make sure everyone was OK. I was very surprised at how much skill that took for me--only a few feet of depth change made a huge difference in my buoyancy.
     
  2. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
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    You make an assumption that they are properly weighted and beginning an ascent makes them positive. That is often untrue and a 3 dive diver is often so severely over weighted with an empty BC parked on the bottom in class that they have to go up 30ft or more to become positive.
    New OOA divers also sometimes dump their BC attempting to put gas into it as they kick up hard and panic. They reliably forget on the surface (if they do make it) to orally inflate their BC too. The fact that this woman sank back down after being assisted partly up suggests over weighting to me. Plus CO2 and panic or just plus - OOA both could have led to her unconsciousness and then drowning. Dropping her weights was/is the right call for a new diver "in trouble" like this far more often than not.
     
  3. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
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    Oh, I have no doubt she was overweighted. As I said, everyone diving a thick wetsuit (as is required in Lake George) is overweighted, and probably more than necessary. What I am saying is that being overweighted requires you to have more air in the BCD to be neutral, and a diver beginning an ascent should have added enough air prior to that to be neutral. In fact, if an oeverweighted diver has achieved neutrality by adding enough air, the real danger is an uncontrolled ascent.

    There was a video clip popularly played on ScubaBoard a few years ago that people said showed the problem of panic. I think they missed the point, because I think it showed exactly what I am talking about. In that clip, you see a group of divers wearing heavy wetsuits. The clip scans the group, and everyone is neutrally buoyant. Then we see someone, likely an instructor, give the thumb, and people start to ascend. Then the film goes to one of the divers, a woman, who we had earlier seen was neutrally buoyant. At this point, though, she is negatively buoyant and kicking hard to keep from descending. Her panic grows. Eventually she fights her way to the surface, in full blown panic. To me it is obvious what happened. When she saw the signal to ascend, she dumped her air, as she probably had been taught (and I have seen that being taught). She then became instantly negative and could not ascend.

    I led a dive trip to Belize a number of years ago, and our group was assigned a DM. Before the first dive, he gave his standard spiel on basic diving skills. He told us to be sure to drop every bit of air from our BCDs before starting the ascent. That works just fine in Belize; it will not work in lake George.
     
    poseident, Bob DBF, eleniel and 4 others like this.

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