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Survivor Bias

Discussion in 'Basic Scuba Discussions' started by jvogt, Oct 18, 2020.

  1. Ana

    Ana Solo Diver

    # of Dives: I just don't log dives
    Location: Pompano Beach, FL
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    I'm glad you opened this new thread. I read most of the posts on the thread you're referring to. Every other post made me wonder what's happened to the people in ScubaBoard. And to be fair it wasn't just this thread with the 108', anything written here that involves crossing the magical 60 foot line unless you have 10 tons of gear with redundancy to absolutely everything, makes you believe the dragons are gonna get you.

    Most of the responses could be narrowed to:
    "I did it 20-30-40 years ago, but I know better now"

    Seriously? You know better now?
    Ooor Is it that you were in your 20's or 30's back then, and now your old behind is not up to the challenge, because you're hedging your bets?

    I'm not advocating to learn to dive today and tomorrow go 150' on a couple of spare-airs . But do not impose your way in other's either. Specially when your way says that it is unsafe to do what people normally do round the world thousand of times before lunchtime without a problem. Oh and that is no problem to the average vacation diver, not the average SB diver... spare me the survival bias, normalization of whatever and all that jazz. Taking a shower is dangerous, driving I-95 in South Florida is not exactly safe, cutting vegetables with dull knives may lead to blood events. Living is risky and will surely end in death.

    Even with the nitrox mixes people are getting carried away. What happened to 99' MOD for 40% ? That's what I followed when I started, not just me but all the people around me did the same. You went out for a 2 tank trip and the mixes were 36 and 40. The dives were 1st around 110' 120' 130 and 2nd to 40-60' none of them were exactly to X' on the 60' reef sometimes you saw something off to the sand and you may end up in 70 for a bit, or whatever, was well within the 99' limit for the 40%. I didn't stay at the edge back then (at least not regularly) and that's pretty much the way I will continue.
    Don't waste time calling me reckless because you "feel" it is safer to keep 40% shallower. I have adjusted my diving to match my aging process and my laziness levels but the level of safety remains pretty much the same. What is reasonable for me today is not the same as for my son in his 30's, but not because I'm safer than him, he's stronger and more motivated. Just because I've already been there doesn't make it unsafe for others.

    It gets old to read how much you guys did back in the day but not today... Oh no, now you take enough gas to circumvent the planet in order to go to 61' solo. You guys take the kitchen sink but of course no knife, only an overpriced envelope opener of some sort.

    Do your dive as safe as you want, but don't justify your ways by calling other divers not-safe or reckless, just because they handle risk differently.


    Ok I'll stand down from my soap box.
     
  2. BoundForElsewhere

    BoundForElsewhere Waiting for the zombies ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: NYC
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    so where do the Darwin Awards fit into these concepts?

    Just a fine line past Survivor Bias, I would imagine.
     
  3. AfterDark

    AfterDark Solo Diver

    # of Dives: 1,000 - 2,499
    Location: Rhode Island, USA
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    Seriously? You expect people to be able to do all the things they did at 20 when they are in their 60s and beyond?

    My SAC rate was never real good even in my 20s running daily. It hasn't gotten better with age. These days I go thru a air like a Hoover. What was within the margin of safety for me in the 1970's isn't today. I can't hit NDL at 100FSW on a any single tank I own, at best it would be a bounce dive.

    Divers need to know their limitations or they find out at the worst possible moment. They have to either equip themselves to mitigate those limitations or limit their diving.

    I get the sky is falling danger, danger part of your post, for a lot of people diving to 100+FSW on a AL80 is well within their abilities, their SAC rate enables a safe dive and it's just the way they dive.

    All the emphasis about depth limits applied to OW / AOW has IMO created a type of phobia / paranoia about deep diving among some divers. A health respect for the hazards involved in dives over 100FSW is good however.
     
  4. Ana

    Ana Solo Diver

    # of Dives: I just don't log dives
    Location: Pompano Beach, FL
    1,637
    1,678
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    I'd say respect for the hazards involved in any diving is good.

    The issue is that what one person considers respect, there's another person that thinks that's disregard and a 3rd person that considers it over-kill.
     
    Bob DBF and captain like this.
  5. Bob DBF

    Bob DBF Solo Diver

    # of Dives: I just don't log dives
    Location: NorCal
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    I've found that getting old is a real pita as well. It's not that against doing the dives I used to, hell I know more and have more experience, it's just that my body is not in the condition it was decades ago and safe diving is about making rational decisions.

    It's faster and easier to train a diver to arbitrary limits, than to teach good judgement and how to use it.


    In the words of Dirty Harry Callahan: A man's GOT to know his limitations.
     
  6. captain

    captain Captain

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    Post of the day.
    I started diving at 14, now I am 76, over the years adjustment had to be made as the ageing process and medical issues arose. Depth and surface conditions have to be factored in, now it mostly shallow calm water. No more diving in 4 foot seas and 3 knot current 30 miles off shore, the physical ability and desire to do that is no longer there.
     
    Julius SCHMIDT and Bob DBF like this.
  7. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
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    I think this segues into an aspect of this topic nicely. When people look at the details of a dive incident and think, "Wow! That is insane!", that may be a result of their not understanding that for the person involved in that incident, it was not insane because that person had the necessary training and experience to make it reasonably safe. I mentioned that before. On the other hand, the opposite is also possible. That person may fully believe he or she has the necessary training and experience but may be sadly mistaken. How are we to know the difference? Here are three illustrations.

    1. A number of years ago, a dive shop owner in Cozumel, her top divemaster, and her boyfriend made a dive intended to go to 300 feet while diving on single tanks of air (2 AL 80s and 1 AL 100). At 300 feet, the shop owner kept descending, either because of narcosis or unconsciousness (stories vary). Her DM caught her at 400 feet and brought her back As their air supplies dwindled during ascent, they ended up doing 3-person buddy breathing off the AL 100 and reached the surface without any decompression stops. The shop owner died, and the DM will never walk again.

    They tried at first to cover up the true story, but eventually it all came out. The DM posted a confession, and when I read it, I was horrified by how little they knew about some deep diving principles, including narcosis and oxygen toxicity, when they did the dive. In the aftermath, a well known figure in Cozumel, someone you would assume to be an authority, wrote to me privately to ask a technical question about deep diving. I was shocked to see that this authority figure did not understand something I would have thought was pretty basic.

    2. A couple years ago, a diver in St. Croix attempted to break the world record for diving depth. The dive shop supporting him in this venture advertised it heavily, referring to him as "Doctor Deep" in professional made videos with dramatic voicing. (The dive shop personnel included someone who did this stuff professionally.) When it was announced on ScubaBoard, the most highly trained people on the board went nuts, warning them not to do it in the strongest possible terms--"You're gonna die!" He ignored the warnings, did the dive, and died.

    3. Two cave diving incidents will be lumped together. A young man named Ben McDonald supposedly died in a cave (his body was never found), and a father and son team died in Eagles Nest Cave. Ben McDonald had no formal cave diving training, and a video in which he appeared briefly showed him to have weak skills and unsafe equipment. The father in the second case was only OW certified, and the son was not certified at all. Eagles Nest is a highly advanced cave dive requiring trimix training in addition to cave certification to dive to the area where they died.

    Analysis
    The dive shop owner and DM had done thousands of dives in Cozumel, and they probably had never seen anyone who appeared to be any better than they were. Even if highly trained technical divers had dived with them, on those basic NDL dives, the skills and training they had in technical diving would not be evident. It would be understandable if they believed they were at the top of the diving world. Other top divers dive to 300 feet--why not them?

    Doctor Deep was a medical doctor who moved to St. Croix in the wake of a messy divorce. He got OW certification and continued to take classes. According to the biographical sketches published, he had soon surpassed the deepest dive his technical instructor had ever done--215 feet! (As a trimix instructor, I am required by standards to take trimix students much deeper than that.) Soon after that, he was preparing for his record dive. In those post-incident biographies, a member of the supporting dive shop said that Doctor Deep knew more about technical diving than anyone on the planet. That statement is stunningly absurd. He was really just a beginning tech diver, and he had no one around him to lead him to believe anything different. He was indeed the best anyone in St. Croix had ever seen, and they mistakenly believed that made him the best in the world.

    In the aftermath of the two cave incidents, social media discussions showed that the friends and relations of the deceased fully believed that the victims were at the very top of the cave diving world. When divers were looking for Ben, one of his relatives wrote that some of the divers doing the search were among the best in the world, "almost as good as Ben." For years after the Eagles Nest incident, their relatives fought to have the cave permanently closed. If divers with the skill and experience of those two dived in that cave, they argued, then it is too dangerous for anyone.

    In response to the details of the first dive, I devised something I called the "I'm the best I've ever seen" syndrome. They have never actually seen anyone performing at a top level and assume that those people are no better than they are. It is what leads people to make foolish decisions--the decisions do not look foolish to them because they honestly do not know any better. So how are we to tell the difference? A couple years ago, after a friend died doing a cave dive that was obviously well beyond my ability and I believe was not so obviously beyond his as well, I tried to write an article on diving beyond your ability. I wanted to provide guidelines for telling the difference between extending your ability reasonably and going a bridge too far. I gave up. I did not know how to do it.
     
  8. MaxBottomtime

    MaxBottomtime Divemaster

    # of Dives: 2,500 - 4,999
    Location: Torrance, CA
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    Ana's post reminded me to add a caveat to my post in the 108 thread. The only reason I would not dive to 100 feet with an 80 today is my high sac rate and my camera. I would probably only get ten minutes or so at 100 feet before having to get shallower. That's not worth taking my huge camera housing. Most of my dives these days are 70-80 feet with a 130, giving me enough bottom time to shoot a lot of photos.

    I used to make a ton of dives between 160-240 feet using double 120s and deco bottles. All of my tech buddies have gone on to other pursuits, so I wasn't making many deep dives for a few years. My last three dives on the UB88 at 185 feet were solo. It is a lot of work carrying all that gear, so I eventually sold my doubles and deco bottles and have relegated myself to recreational dives. If I found a new wreck in deeper waters I might consider borrowing or buying doubles again, but for now, I'm happy with 60-80 minutes at 70 feet on a single tank.
     
  9. BoundForElsewhere

    BoundForElsewhere Waiting for the zombies ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: NYC
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    other than wrecks, what's to see past 100'? doesn't the light get filtered so much coral and plants don't live down there? maybe big pelagics but if you cut your buddy's finger and let him bleed for a little while won't they just come up to where you are?
     
  10. drrich2

    drrich2 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Southwestern Kentucky
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    You'd need to define the standard one has to meet to be said to 'know' what they're doing.

    How many divers know the odds of serious injury or death on an average mainstream recreational dive? Or how to judge how those odds might vary in different conditions (e.g.: cold water, depth > 80 feet, current, etc...)?

    Next, you've got to define the standard for acceptable risk. If I want to do a dive, and my odds of dying on it are 1 in 10,000, is that acceptable risk? For a typical recreational dive, maybe not. But what if it's a special dive to see large numbers of manta rays, or dive with tiger or bull sharks? Is the 'bucket list' factor a justification for added risk?

    How do these risks compare to those of other things we do? How does the risk of a morning dive trip with 2 1-tank 80-cf AL rec. dives compare with a 6 hour round trip road trip for the family to enjoy a couple days visiting a public aquarium? Or hiking or skiing?

    I think people rely on herd conventional wisdom a lot. If the 'diving community' thinks solo diving is too dangerous, or going below 130 feet without technical training and equipment, over overhead diving without special training and prep., is too dangerous, they think it is. They're often right. And if they're told a 45 minute dive not over 60 feet in good conditions with a buddy on an OW cert. is okay, then that's fine. Is that an example of 'knowing' what they're doing?
     
    Esprise Me and Lorenzoid like this.

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