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Insta-buddy DECO Diver: What’s NDL?

Discussion in 'Near Misses and Lessons Learned' started by Soloist, May 26, 2019.

  1. Soloist

    Soloist Solo Diver

    # of Dives: 500 - 999
    Location: North Carolina
    799
    1,045
    93
    I’ve been reluctant to post this incident, but considering the concerns raised by the Accidental DECO and mild panic in a non tech certified diver. thread it’s relevant. The intent of this post is not to embarrass, impugn or criticize, but rather further the discussion, awareness and edification.

    I have been very fortunate to have only ever had one dive buddy. It’s either her or “no-buddy” since we are both avid solo divers. However, I did have an insta-buddy experience. He was an extremely nice, funny and wicked smart individual with a doctorate in medicine. I immediately asked about his experience, training and comfort level. He had been certified roughly twenty years earlier, but had not been diving in a very long time. He was using rental gear including a dive computer. We were doing minimal current anchor dives with 50 feet visibility, 60 minute max with air filled aluminum 80’s. Nitrox was unavailable. Seriously?

    The boat was delayed getting underway due to several cruise ship divers yet to arrive. No problem. The first dive was a shallow wreck and reef with an average depth of 35 feet. My new buddy was very relaxed, trimmed, controlled, alert with better than average gas consumption. Great! At 45 minutes I noticed we were the last two in the water, but he signaled everything was fine, so we continued to explore until it was time to go up.

    Thirty minutes after we exit the water everybody starts gearing up. I mentioned our minimal surface interval time to the dive mate, but it was dismissed. I assumed they were rushed due to the late departure, but it was irritating nonetheless. So my buddy and I splashed after a 44 minute SI. Not a problem if diving nitrox, but diving air? Moreover, the group immediately descends to over 80 feet. There’s a dozen curious reef sharks buzzing around, so I am interested in extending the dive for a long as possible. My NDL is plummeting, so I signal to my buddy we should move up to the top of the reef. Throughout the remainder of the dive I’m pointing at gauges and receiving okay signals in response. Once again at 45 minutes into the dive we are all alone, but continue with our dive for another ten minutes. Average dive depth 49 feet.

    As I am coming up the ladder the DM says “hey, sorry for coming up so early, but I went into DECO”. Really? I stated I was down to 11 minutes NDL at one point. He laughed as as if I told him we were hanging out with Elvis and riding purple unicorns during our safety stop. I was compelled to tell him my Shearwater Perdix gradient factor was set for low conservatism. Out of curiosity I asked my buddy about his NDL on that last dive. He responded with “what’s NDL”? No freaking way! I questioned if he was serious. He was. Turns out he had gone into DECO, locked up his computer and was completely oblivious.

    I impulsively launched into a long self righteous rant about NDL fundamentals, why it’s critical to monitor NDL, accumulative nitrogen associated with repetitive diving, computer essentials, DCS, blah, blah, blah, BLAH, BLAH!!! In other words, I felt responsible. He said he felt fine, but was genuinely appreciative and concerned. Then proceeded to do the night dive he scheduled with a different dive op and was back on the boat the next morning. The dive mate did reprimand him though by saying “don’t lock up any more computers, because we won’t have enough to go around, haha”! I kid you not, so he used yet another computer the next morning. Fortunately, I believe my deco-buddy has a newfound respect for NDL.

    This level of complacency is concerning. Is scuba diving becoming the equivalent to bungee jumping, whitewater rafting and zip-lining?
     
    stuartv, Schwob, rabe and 2 others like this.
  2. davehicks

    davehicks Barracuda

    # of Dives: 1,000 - 2,499
    Location: Seattle
    307
    186
    43
    In a post where you mention "cruise ship divers" my answer is that No, it's not surprising.

    But seriously, in places like Cozumel the norm for dive ops is to impose the 45 minute / 60 foot rule for exactly this reason. Many of their customers are occasional divers and don't have the sort of experience, training, exposure to people like yourself who can really imprint safety practices into their brains. This really does require ongoing reinforcement for many to transfer the class training into real understanding.

    I don't want to be self righteous here either. When I started diving in 1990 my computer did not warn of NDL because I didn't own a computer nor did most others. I ran the tables, but it got a bit loose after repetitive dives on air. Many a time I came home with achy joints that I am sure were decompression stress. It took me being part of a dive club with more experienced divers around to really understand and embrace safety culture.
     
    Sam Miller III, Lorenzoid and Soloist like this.
  3. Divectionist

    Divectionist Solo Diver

    # of Dives: I just don't log dives
    Location: Gold Coast, Australia
    247
    112
    43
    You already did what you could given the situation - ask for OK's on the gauges throughout the dives - their failing is not your responsibility. Nevertheless, I think it is good that you went on your rant to educate your buddy further. Who knows, it may save him way down the track.

    I've noticed on boat dives where divers rent shop gear that most don't have the first idea about how to read the info on their computers (the cheap computers generally used don't help with their unlit confusing screens) and are given no intro by the staff either. Pair this with the inability to have a dive plan in your head (often unknown location led by guides or DMs), divers essentially have no idea what is going on, other than a dive time or reserve pressure limit.

    Real world diving is so far from the level of thought and procedure given to it by members of this forum, you may as well call it zip lining.
     
    Soloist likes this.
  4. drk5036

    drk5036 Nassau Grouper

    # of Dives: 50 - 99
    Location: Sapporo, Japan
    145
    56
    28
    Honestly, in this case, what's the point of having a dive computer? He'd be just as safe "following" your dive computer, since he doesn't know how to read his own.

    This is often how things are run in Southeast Asia. Dive as a group, everyone has to go down and come up together, and everyone "follows" the DM's computer. Then just hope and pray no one gets sick (no computer to analyze for why) or separated...
     
  5. johndiver999

    johndiver999 Manta Ray

    # of Dives: 500 - 999
    Location: Gainesville FL
    768
    645
    93
    I generally prefer to avoid giving hand signals and receiving hand signals for computer and air pressure. To be honest, I don't really know the standard signals for pressure etc.

    I prefer to just show my console and in general, the buddy responds in kind. Possibly, if both divers were looking at his computer, he might not have violated it.
     
  6. divinh

    divinh Photographer

    # of Dives: 100 - 199
    Location: San Francisco
    723
    280
    63
    I don't know if the conclusion you arrived at can be established with having had just /one/ dive buddy, who had not dived in about 20 years, likely someone who only had done trust me dives, as dive computers probably weren't as accessible for individual ownership so many years ago.

    The DM went up earlier because he went into deco, which is the responsible thing to do. If he was using a Suunto, for example, why would that be shocking that his dive computer would go into deco before a Shearwater, even on low conservatism? (I don't have a Shearwater or Suunto, but from what I've read, the Shearwater's are vastly more liberal.)

    Many DM's ask what everyone's dive computer is, especially when dives could go into deco, to see which would likely go into deco before others. That's likely from their experience of having to dive with many insta-buddies. They go with whichever is the most conservative, to prevent lock-outs among all their customers. From that, I know to see what dive computer my buddy is diving with. Since my primary dive computer is a Cressi, I already know it's pretty conservative so if I approach deco, my buddy is likely around there too, or still safely in NDL.

    I'm glad you educated your buddy on NDL again, but it's one of those situations when the dive op should have pushed for a refresher course.
     
  7. Soloist

    Soloist Solo Diver

    # of Dives: 500 - 999
    Location: North Carolina
    799
    1,045
    93
    You are right. Unfortunately I found it impossible to tell this story from my perspective without sounding self righteous or negative towards insta-buddies. Honestly my intent was to elevate the issue not myself. In retrospect everyone involved was complacent. The insta-buddy did not do a review or take a refresher prior to his five days of consecutive diving after an extremely long layoff, nor do I believe he informed the dive op of his history. The dive op did not do a full one hour surface interval from the last diver out of the water even though everyone was diving air. The first dive was very shallow while the second was considerably deeper. Moreover, the dive op all but ignored the fact that one of their divers went into deco. As for me, I selfishly didn’t want my dives abbreviated, so if my buddy says he’s okay then he’s okay. The algorithms for budget dive computers vary greatly, but I should have assumed his rental computer was more conservative than the very liberal settings I have programmed into my Shearwater.
     
  8. Lorenzoid

    Lorenzoid idling in neutral buoyancy

    # of Dives: 500 - 999
    Location: Atlanta, USA
    8,869
    5,318
    113
    I too avoid diving with insta-buddies, but if I did, I like to think I would do the same sort of simple dive planning I do with my regular buddy while we’re gearing up: “The DM said the depth will be about XX feet. My computer [in planning mode] shows we will have about XX minutes of no-deco time. Does that agree with your computer?”

    Since you ordinarily dive solo, that kind of interaction might not occur to you. For me, that’s just the minimal planning I would do on any dive.
     
    Soloist likes this.
  9. hammet

    hammet Manta Ray

    # of Dives: 200 - 499
    Location: United States
    552
    460
    63
    Even pros do bonehead things. I splashed with an instabuddy a few weeks ago who had hundreds of dives and was a certified DM. I had to turn his air on for him... after we were already in the water.
     
    Soloist likes this.
  10. arcticat99

    arcticat99 Barracuda

    # of Dives: 25 - 49
    Location: Saskatoon Sask canada
    320
    160
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    i been on 6 different "cruise ship "dives it works for me and my wife cause she doesn't dive.but on all the dive shops were very conservative with there dives.no longer than 45 minutes each with 1 hour surface intervals this is a standard from the cruise ships when you book excursions through them .and you never have to worry about leaving you behind .one of their guarantees
     

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