First cave dives

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beester

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Heya Bluetrin and Esprise me... I agree with you (specially Esprise me)... you are right in some way.

I still believe it's very hard to quantify risk, and I also think that most people underestimate the chance of incident ("it will be alright").

There are just too many variables... in the end it's a matter of context. Put an OW/AOW diver 200 m in a cave and chances are good he will get out alright and spread the word on scubaboard that cavediving isn't that hard at all... ;-) but in 1% of his dives his light fails and he doesn't make it out because he has no backup light, procedure in place, he panicks and he dies. For the cave diver in 1% of his dives his light will also fail, but it's a non incident... he just deploys a backup light, signals his team members, gets sandwiched between his team members (safety) and they call the dive. It's not even mentioned in the post dive brief... it's not even an incident. Why? Because he and his buddies have the equipment, training, experience to make it a non issue.

So this group of cave divers, might go deeper in a cave (1Km in), and they don't have a light failure, but a complex failure (dropped stage without gas, plus limited visibility because of percolation), this still should be a non issue... but the risk indeed is higher.

I'm not able to quantify risk, I know how I plan my dives, with my buddies... but I am sure that if you put an inexperienced diver without training in a harsh environment, the 1% chance of incident will probably be a 50% chance of death when it happens... while for the experienced diver (in that environment) it probably won't be an issue.

Not sure if I make sense...
 

Esprise Me

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Definitely makes sense. I do think the numbers can help with conceptualizing risk, even if they're neither very precise nor very accurate. I had to look into the math, because I was thinking in terms of multiplying the odds of an adverse outcome by the number of repetitions, which gets you pretty close with smaller numbers, but obviously repeating a 1% chance 100 times doesn't equal 100% probability. What you really need to do is raise the odds of success to the power of the number of times the risk is taken. So, diving to the NDLs carries a 1% risk of DCS, which is a 99% chance of not getting bent. 0.99^100 = 0.63, or a 63% chance of DCS occurring at least once if you do 100 dives right to the limits. If you've done 99 dives to the limits already without incident, your risk on the hundredth dive is still 1%, but don't be lulled into thinking it's less. Of course, getting bent is not a death sentence; if you have oxygen on the boat and a hyperbaric facility nearby (and good insurance), you might decide that those 63% odds are acceptable to you. To me, no way. I will be keeping a nice cushion on all my dive plans. I have also passed on a lot of other risky activities that seemed fun because I wasn't comfortable with the danger. But others can make different decisions--to a point.

The other factor people in this thread have pointed out, which OP hasn't really responded to, is the impact on others. Sticking with the assumption of 1% risk of death for untrained divers in a cave, let's imagine 100 untrained divers over the course of a year enter a particular cave. Odds are at least one of them will die. If 1,000 untrained cave divers do it, odds are at least 10 will die-- and the odds of at least one death become overwhelming at 99.99568288%. This basic idea applies no matter whether the postulated 1% risk is over or under. The effect of these deaths may include the cave being closed to all, to say nothing of the effects of 100-1,000 people stirring up silt, breaking stalactites, and imperiling other divers in the cave. Looking at just the 1% risk to yourself is a bit like just looking at the risk of being fined for taking a shell out of a marine preserve. Maybe you'll get away with a real benefit to yourself and no measurable harm to anyone, but we can't all think like that or it'll suck for everyone.
 

kafkaland

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Irrespective of all statistics, for me the calculus is simple: if I want to engage in an objectively dangerous activity like cave diving, I will try to manage foreseeable risks. And most risks in cave diving can be managed very well with the right training and equipment, so getting those is a very potent part of any risk mitigation strategy. Just telling yourself that you are a good OW diver and your best guess is that that particular cave isn’t all that dangerous, on the other hand, won’t do much when things eventually go sideways.
 

Princess Chris

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I'd like to thank the OP for starting this and some of you experience cave divers for beinf so honest as its a good guide on what to do and what not to do. I'm a relatively experienced with overhead enviroments but cave dives have always scared the bejeezus out of me (thanks sanctum). However being the idiot that i am, i would definitely like to give them a go. At no point was i considering just heading into one and hoping for the best, this thread has given me a good bit of extra insight into cave diving and a chuckle at 60plus' expense (sorry)
 

BlueTrin

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Heya Bluetrin and Esprise me... I agree with you (specially Esprise me)... you are right in some way.

I still believe it's very hard to quantify risk, and I also think that most people underestimate the chance of incident ("it will be alright").

There are just too many variables... in the end it's a matter of context. Put an OW/AOW diver 200 m in a cave and chances are good he will get out alright and spread the word on scubaboard that cavediving isn't that hard at all... ;-) but in 1% of his dives his light fails and he doesn't make it out because he has no backup light, procedure in place, he panicks and he dies. For the cave diver in 1% of his dives his light will also fail, but it's a non incident... he just deploys a backup light, signals his team members, gets sandwiched between his team members (safety) and they call the dive. It's not even mentioned in the post dive brief... it's not even an incident. Why? Because he and his buddies have the equipment, training, experience to make it a non issue.

So this group of cave divers, might go deeper in a cave (1Km in), and they don't have a light failure, but a complex failure (dropped stage without gas, plus limited visibility because of percolation), this still should be a non issue... but the risk indeed is higher.

I'm not able to quantify risk, I know how I plan my dives, with my buddies... but I am sure that if you put an inexperienced diver without training in a harsh environment, the 1% chance of incident will probably be a 50% chance of death when it happens... while for the experienced diver (in that environment) it probably won't be an issue.

Not sure if I make sense...
I think you make a lot of sense.

I think the best way to use any figures like this is to use them as an additional indicator to have an order of magnitude: as you said these figures will be very rough.

It is not directly related to this thread (and cave diving) but I find this link interesting in regards to scuba statistics:

Scuba diving fatalities - Wikipedia
 
OP
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60plus

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Just to clear up a point. I was not a health and safety lecturer, I was primarily an engineering lecturer but part of that included health and safety modules. My background in assessing risk when penetrating confined environments (chemical, petrochemical and land based industries) does put me in a much better position than most, probably nearly all divers of similar diving experience when evaluating risk. I think too many posters on here have jumped to too many negative conclusions regarding my cave dive. If you look at guided diving in these areas it has a very good safety record. The not infrequent cave diving deaths that have occurred have been unguided. I am not saying what I did was risk free, and i accept the risk was greater than shallow OW diving but the level of risk was to me and the others on that dive acceptable. Were these very frequent cave dives high risk there would be a lot of deaths and litigation, which there is not.
In an earlier post I mentioned a couple of local road accidents. The motorcyclists injuries are described as serious but not life threatening. The lad who was paralyzed is now not paralyzed, he has severe bruising to his head and a strained neck.
 

Dan G

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Just to clear up a point. I was not a health and safety lecturer, I was primarily an engineering lecturer but part of that included health and safety modules. My background in assessing risk when penetrating confined environments (chemical, petrochemical and land based industries) does put me in a much better position than most, probably nearly all divers of similar diving experience when evaluating risk. I think too many posters on here have jumped to too many negative conclusions regarding my cave dive. If you look at guided diving in these areas it has a very good safety record. The not infrequent cave diving deaths that have occurred have been unguided. I am not saying what I did was risk free, and i accept the risk was greater than shallow OW diving but the level of risk was to me and the others on that dive acceptable. Were these very frequent cave dives high risk there would be a lot of deaths and litigation, which there is not.
In an earlier post I mentioned a couple of local road accidents. The motorcyclists injuries are described as serious but not life threatening. The lad who was paralyzed is now not paralyzed, he has severe bruising to his head and a strained neck.

The issue is not "How risky is a dive?" The issue is, "Do I have the training to deal with a problem if things go sideways?" Cave divers go for countless dives with no issues. Years... decades with no issues. What people are trying to point out to you is that despite the fact that your dive went just fine, it doesn't mean you could have dealt with a problem. Even your description of how your team dove together ("nose to fin") illustrates a lack of training. The risk you assessed was based on if nothing went wrong.
 

BlueTrin

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The issue is not "How risky is a dive?" The issue is, "Do I have the training to deal with a problem if things go sideways?" Cave divers go for countless dives with no issues. Years... decades with no issues. What people are trying to point out to you is that despite the fact that your dive went just fine, it doesn't mean you could have dealt with a problem. Even your description of how your team dove together ("nose to fin") illustrates a lack of training. The risk you assessed was based on if nothing went wrong.
I think what 60plus means is that all in all, his chance to die is not that high in this kind of environment.

Surely he acknowledged he is not cave trained but he believes that the kind of passage is safe enough so that his tail event is fairly low in probability.

So by saying this, he is saying that he actually included the chance of it being wrong.

You can disagree with his assessment :)
 

Jay

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In 1979, Sheck Exley wrote the book "Basic Cavediving: A Blueprint for Survival" to help explain some of the hazards. Although the book is celebrating it's 40th year of existence, much of the content is still relevant. Last year, the NSS-CDS decided to give away the manual for free, please take the time to download and read a copy, it may save your life.

https://nsscds.org/wp-content/uploads/2018/05/Blueprint-for-Survival.pdf

My best,

Ken

Thanks for sharing that book. It's an excellent read.
 
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