The Unearned Bullhit

Doria_2So there I was, having breakfast with my good friend Dr Nick at the usual hotel before the Our World Underwater show in Chicago a few months ago. Nick is one of the most knowledgeable guys I know on the subject of decompression theory and physiology, and if he is talking then I am definitely listening. Anyway, we are talking about divers doing stupid stuff, and then he starts to talk about something serious, an unnamed diver who suffered an "unearned hit". An "unearned hit" is one of those politically correct terms now used to describe a decompression sickness (DCS) event where the diver has supposedly followed all the rules, and done absolutely nothing wrong, but still ends up bent for reasons that remain a total mystery??? "Unearned hit" really means unexplained hit to me.

Just to be clear, we are not talking about divers with serious medical problems that end their diving careers until the medical issue(s) is resolved, like PFO's or any medical condition that affects diving and decompression. Events like these are truly unearned by the diver, but explainable. We are also not talking about divers who get caught doing stupid things that end them in the chamber, and hopefully they then learn a lesson. What we are talking about here are divers who are healthy, have a DCS event, and then claim a mysterious unexplained, "unearned hit", and then return to diving, of course after a stint in the chamber and a short rehab on the beach, having learned nothing.

Just the use of the term, "unearned hit", is enough to get me going, so I had to stop Nick in mid-sentence. I asked him if he meant unexplained hit, as opposed to unearned hit, and he thought for a second, and responded positively. I told him that so long as there was not a medical background to this particular case, I was able to explain it completely, entirely, without even knowing all of the dive particulars. The reason I was able to explain it was because there is one, and only one reason for DCS in a healthy diver.

Bill Nagle_2

Every single case of DCS in a healthy diver, without exception, has been caused by the diver..... not doing enough decompression!!! That is it. I just assumed that science guys know this, but apparently not?

It is not really that complex is it? The cause of DCS, is coming to the surface too soon, without having done enough deco. Now the causes for coming to the surface too soon are almost infinite, and there are divers who take responsibility for their mistakes, and learn from them. But "unearned hit" is really a lot of,  "let me tell you my story of how I am too smart to get bent, and I did nothing wrong, and blah, blah, blah, blah, blah."

When I first arrived in London to dive the Lusitania, in 1994, the expedition leader had just been treated for a pretty serious Type II DCS hit involving some paralysis. I was not only worried about her, but sympathetic to her situation, and none of us were sure how this would impact our expedition? When she was finally released from hospital, she told our group what had happened.

She went down to the tabled depth, but the grapnel was a little deeper, so she went down and secured it, she did her dive and she was right on time coming back, but after she had started up the line she remembered the hook, and went back down to free it, and she did not understand why she got bent....... it was a totally "unearned hit".  I mentioned something to the effect that it was totally "unearned", except for going over on time... AND depth!!! My comments were not well received, but I am experienced at saying the wrong thing.


A few years ago, a friend of mine got himself in trouble in the Pacific. When I saw him after he returned, he sheepishly told me how even the chamber operator had agreed with him that it was a totally "unearned hit"! However, I had already spoken to another friend of mine who was there. I do not mean to be unkind, but this guy was overweight and out of shape at the time. It was his first dive of the trip, it was deep, he was jet-lagged, and stayed up into the wee hours drinking with friends the night before the dive.  So, he was claiming the hit was "unearned", except for his lack of fitness, the lack of sleep, the abundance of alcohol, the dehydration, and the stress of travel. Aside from that, it was totally "unearned", because his rebreather computer told him to surface? Seriously?

This is the deal, it does not matter whether you use a computer, or tables, or just remember your dive plan in your little head, you are the only one responsible for when you come to the surface. Come up too soon and you will get bent. I have made thousands and thousands of dives, and understanding this simple premise is the only thing that has kept me from being bent.

Is there a check box on your dive planner, or a button to press on your dive computer for any of the following?

  • Are you seasick, or did you start out feeling not too good to begin with?
  • Are you tired, sleep deprived, or jet lagged?
  • Are you dehydrated?
  • Is your individual cardio-pulmonary efficiency poor for any reason?
  • Are you out of shape or carrying too much weight around your middle?
  • Are you stressed out at work, or are you stressed out at home?
  • Did you do a lot of swimming or hard work on the dive?
  • Did you get cold, or wish you had worn your drysuit?
  • Did you scare yourself?
  • Were you lost?
  • Is that 12' shark a bull or a white?
  • Are you going to get your butt kicked on the surface because the environmental conditions are a tad challenging this afternoon?
  • Did you breathe more gas than usual today, for any of the many possible reasons?

I love my dive computers, but mine doesn't have an "I am seasick" button, and I would imagine yours probably doesn't either? Computers and tables give us mathematical predictions, based on time and depth only. They provide information, which is just a bunch of numbers based on an algorithm estimating typical human physiology at a molecular level. If this stuff was an exact science no one would ever get bent, but that is not the case, is it?
noticeWhen we look at the information from our computer or table, it is only numeric data for a baseline dive based on time and depth. Then........ and I know this is hard to believe, but the diver needs to get personally involved, and interpret this data as it applies to himself/herself on that particular day, and that particular dive. You may need to buffer the calculated hang, safety stop, or ascent. Just because the computer, and/or tables say it is okay to surface, does not mean that it is absolutely safe to do so.  There is a lot that the computer and/or tables simply don't know about your dive. You should know more than the magic box!

I hope none of you are ever in this situation, however if you do not interpret the data correctly, and you don't do enough decompression, and you get yourself bent, please do not call it an "unearned hit", simply because it is totally, unabashedly, "earned" by you. Utilizing politically correct and wholly inaccurate terminology to hide the fact that you are a jackass is not going to make you a better diver.  Nor will this earn the respect of anyone who knows anything. DCS of this kind is not a mystery, it is not caused by the hand of god, and it is not all complicated like brain surgery. The cause of DCS is not doing enough deco.




24 Responses

  1. Bravo. Excellent point regarding the "hidden" causes of DCI.
  2. John, You are spot on with your assessment here. I agree that too many divers do not take personal responsibility for their own actions. Personally, as I 've gotten older and and hopefully wiser I dive more conservatively. Last weekend when we were gearing up for our dive on the RBJ (260fsw) I noticed that I was running a little shorter BT than the rest of the divers, that's OK, I stuck with my plan because I knew it was right for me based on my personal experience at that depth. I set v-planner to conservation factor of +2 ... one for each of my children.
    • John Chatterton
      And when you left, I understood that you were adjusting the dive to be more responsible, not less responsible. That is the way to keep diving. Thanks for the feedback.
  3. Larry Weatherall
    EXCELLENT article and I agree wholeheartedly with lack of deco time being the reason for the "unearned" hits. It seems so simple when it's viewed at the most basic level! Love your articles, keep up the good work!
  4. Thank you! Thank you for putting into an article what I have been thinking for years but have been a little reserved in saying. I say a little because I have also had conversations with friends or friends of friends who have been hit where I do not agree with them when they talk about these "underserved hits" (that's what we call them). While I don't think anyone "deserves" a hit, without fail in the dive recollections I have heard, there are plausible explanations as to why the hit occurred and all have been diver related aka "user error." No one wants a hit, but to not think about outlying factors and make adjustments in your dive plan to account for them especially with more technical dives, can land the divers in a higher risk zone. I'll be sharing this blog on our dive shop FB pages. :) -nicolle
  5. Thanks, this was a good read and information every diver should be absorbing. Too many divers take what we do too lightly. I've said many times the most important piece of equipment we have is between our ears and I don't think enough people use it well enough.
  6. Michael Apke
    Last September I purchased a compressor off of Paul a diver in his middle to late sixties. He was selling gear due to type2 hit. Paul has thousands of dives around the Great Lakes and more souvenirs than most museums. (That’s another subject.) He was on a 170 foot air dive. His bottom time was about 11 minutes. His safety stops and deco profile were all good. I even had seen a computerized graph of his dive profile, and it looked conservative enough. He took serious type 2 hit and it was 6 weeks later and Paul was still hobbling around from paralysis. According to Paul he will never deep dive again. Paul thought he did everything correctly. I have no experience compared to this guy that was diving since the sixties. I was surprised at his answer when I asked Paul about hydration before the dive? Paul responded “I was ok I wasn’t thirsty”. I do not know the reason for his type2 hit. I believe as we get older we have to do more deco, more hydration, more exercise, etc. I draw a parallel to my shop security. I may add a lock or power off the garage door openers, but I keep adding and changing things to keep the bad guys out. I never remove security.
  7. Ilan.B
    Great article. Last month a rebreather diver in my area (Red sea) was driving for 6 hours didn't get enough sleep, he is overweight and had a minor flew, went for a dive to 60 meters and the next day to 70 meters. Coming out from the second dive he was Suffering from dizziness and vomiting. He was treated in the chamber for inner ear DCS five times and has some problems with ballance till now. His computers were "clean" and the schedule was perfect.......
    • John Chatterton
      This is a good example of what we are talking about. Thanks for sharing.
  8. Mike
    Great article John. My thoughts have always been that tables /computer is a guide only. If youve worked hard or felt sick and dehydrated or not feeling it that day, why not add a few mins to the stops. I may add a min to half max depth and then two to the next stop and so on. Stay fit. Stay hydrated. Stay safe
    • John Chatterton
      "Guide" is an appropriate term to use. Thanks.
  9. Allen Mac Tavish
    Far to often , after experiencing a hit, most divers will try to reason the incident into something other than diver error. Let me be the first to say , that I not only agree with you John , but stress the point that if youve still got air on a deco hang then a few more mibutes never hurts .Just plan those deco minutes ahead of time. Cheers
    • John Chatterton
      A few extra minutes spent on the hang, seems like incredibly cheap insurance against DCS. Thanks for your comments.
  10. Gareth
    Enjoying your blog John, first the knives post and now this, common sense and experience. The number of times I've heard and read discussions of 'Undeserved hit' usually along the lines of I only did x Minutes at x Meters, & everything was fine. Ask them a few probing questions and finally you hear about the 'small' problem they had, during or prior to the dive... It drives me crazy when people get DCI within there first couple of hundred rec dives. I would even go so far to say the 'undeserved hit' then becomes their badge of honour.
  11. Tom Palmisano
    Been there seen it done it. John,you are dead on!
  12. [...] Read Johns full blog on his website here [...]
  13. Graham Strowes
    A well written piece, I've always been annoyed with the term. It amazes me when I see people on various diving forums complaining about certain brands of computer being too conservative. It's almost as if diving conservatively is bad! A few extra minutes of bottom time is not worth a chamber visit.
  14. John, Thank you for taking the time to write this article. Before I met you, I truly believed that I had taken an unearned "hit" on one of my trips a couple of years ago. Although my hit was a very minor one, it was a serious wake up call. After taking your class and having this discussion among countless others on the topic, I now feel much better educated about this subject, and I also feel much more confident as a diver understanding how my pre-dive actions had a direct outcome on my health post-dive. Since taking your class, I now understand what I have to do to not get bent. Thank you so much John. You are a true role model and inspiration to me.
  15. Mike Pizzio
    Heresy I say! Heresy! Burn the witch Chatterton! Everyone knows that all of these "famous in their own minds" divers could never "earn a hit" when they are so...well...famous...but no one outside of diving websites has ever heard of them... Here are some of my favorites- 1. "I dive helium but lie to my computer and tell it Im diving air" (lie to your wife, lie to your boss, lie to your accountant, lie during confession, but please don't lie to a plastic box)... 2. "I have open circuit tables that a buddy of mine produced (from where no one knows) so I dive them on my CCR with helium dil"...I only dive tables from a buddy if his name happens to be Buhlmann. 3. "I average depth on deep dives because I only spend a few minutes on the bottom at 270 fsw, so I run a 240 fsw table"...Hmmm, apparently we forgot that pressure and diffusion lesson in PADI Open Water... 4. "Everyone knows there is a helium penalty so I shave deco at the shallow end"...Yup, just trim the fat off of those tables pal. 5. "Its not the quantity of the deco its the quality" (Really? So what is a treatment table there pal? Its a long time spent on high O2 at relatively shallow depth. So your stop at any depth is of a better "quality" than mine at the same depth? Do you produce bubbles that diffuse faster across a cell face than I do?) These are just a few examples of a special kind of stupidity that is out there in the diving community. Mike Pizzio
    • John Chatterton
      Thanks Mike. The late Bill Hamilton used to say, "What works, works." However, if you get bent just once, it isn't working. :)
  16. [...] I kinda like John Chatterton's take on an answer to the question "bent diver - what went wrong?" - not enough deco The Unearned Bullhit | Shadow Diver | John Chatterton [...]
  17. Spot on!
  18. Robert H. Hughes
    Awesome Post John: I know you are not one to "skirt" around an issue and will say it like it is! I had a friend who dove Bonne Terre mines a few months back, dove his first dive there to 65' and ended up bent and did three chamber rides as a result. What is a relevant part of this story is- He is a DOCTOR. He came back and said those words to me we all love to hear- "It was an undeserved/unexplainable Hit"! I asked him 3 questions and then gave him my "professional" opinion. 1st question- I asked him did you drive there? He answered- "Yes I arrived at the airport after flying back in from Bonaire early that morning and my car was at O'Hare". 2nd question- Did you sleep on the plane ride back? His answer- "No I can't sleep on planes". 3rd question- Did you do alot of diving in Bonaire? His answer- "Hell Yes, 4-6 dives a day, It's Bonaire". Upon answering my last question I gave him My "professional" assesment of his hit. I explained to him (also being rather upfront) that he is "a complete idiot and ALL the money he spent on Med. School and dive training was a complete waste"!!! I not only could explain why he got bent but that if he couldn't see the reason he had might want to consider Golf as a hobby instead? Here is a Doctor who had just spent 10 days in Bonaire diving 4-6 dives a day, flew in the morning of his dive and had no sleep to boot and couldn't understand why he had got bent? It amazed me and also made me think that someone of this "educated" stature could not grasp what a very simple reason there was for ending up bent. He went on to say that his computer did not give him any warning that this was possible and he followed it religously? I asked him if he explained to his computer that he had just got off a plane and was exhausted with lack of sleep and had been diving like crazy for ten days before he strapped it on and dove? He replied with an explitive I will not post here!!! I wish that some divers would realize that the computer is not the answer, it is meerly a suggestion to avoid a problem based on algarithims and assumptions.
  19. I will ditch my group and dive guides (e.g. in Asia Pacific locations) if necessary and head up the slope and compass bearing on a rec/photo/video dive if I believe that bottom time is extended. They can catch up with me as I enjoy the light at 10 or 20 feet for extended times. Older, heavier, and factoring....
    • John Chatterton
      Being responsible for yourself? I like it. JC
  20. In Feb I dove off Koh Lanta at Hin Daeng, not a super deep dive at 28m, but I'd arrived the day before after 18 hours of travel, didn't during much on the 4 hour boat ride even though I spent more than and hour tweaking my rig. Everything went to plan by the computer on my arm. But it couldn't account for the fact that there were mantas to watch and film, and the finning to hold position in the current. It couldn't know my working SAC would go from 22 to 30 pushing through the current as we followed the reef ridge up almost expertly on my NDL limits. It couldn't know when it said "deco clrd" that I probably still owed 10 minutes at least, and likely needed a high mix O2 tank dropped. And worst, it couldn't tell me I was done diving that day, instead I followed with the "shallow" dive at 18m. And two hours on the way home, my shoulder hurt, but by dinner it was gone, so I dove two dives the next day (25m & 21m). And on the way home, it was clear I had skin bends. But while I sat with the docs at the chamber two days later (because after breathing O2 and a visit to the dive doc, with no neuro symptoms I was told to just not dive the rest of the week - but 36 hours later, the skin bend was back like fire, and I was off to the chamber) I wasn't talking about unearned, I knew I wasn't in top shape, I knew I rode my profile tight, but I kept looking for answers, other present and contributing factors I could have understood better to change the results of my injury. I'm making my first dive 60 days later this afternoon, and trust me, the computer on my shoulders is much smarter today. Thanks for the pearls of wisdom. Just thought I'd share that some of us do learn and don't make excuses.

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