Coroners Report. What do you think!

[Ken Kurtis]

Has there been any study as to the correlation with fatal and nonfatal accidents and the type of buddy the diver had - instabuddy, regular diving buddy, solo, etc.

Good question and not to my knowledge. The thing you'd need to remember should any study like this be attempted, is that as you slice and dice the categories into smaller and smaller chunks, the magnitude of error is going to increase. In other words, one or two more (or less) in a given category skews the results greatly.

We use this as an example in our annual "Why Diver Die" seminar at the Scuba Show in Long Beach. We average 5 fatalities/year in L.A. County. In 1998 there were 4. In 1999, there was 1. In 2000, there were 4. Did diving suddenly become 4 times safer in 1999 and then 4 times more dangerous in 2000? No. But when you break the numbers down into smaller and smaller groups, one more here or one fewer there distorts the picture. Longer/larger looks are better in determining the correlations that you suggest.

 

[jejton]

Good question and not to my knowledge. The thing you'd need to remember should any study like this be attempted, is that as you slice and dice the categories into smaller and smaller chunks, the magnitude of error is going to increase. In other words, one or two more (or less) in a given category skews the results greatly.

We use this as an example in our annual "Why Diver Die" seminar at the Scuba Show in Long Beach. We average 5 fatalities/year in L.A. County. In 1998 there were 4. In 1999, there was 1. In 2000, there were 4. Did diving suddenly become 4 times safer in 1999 and then 4 times more dangerous in 2000? No. But when you break the numbers down into smaller and smaller groups, one more here or one fewer there distorts the picture. Longer/larger looks are better in determining the correlations that you suggest.

I don't know if the analysis would be as hard as you imply. The bigger question is if there are enough incidents, fatal and non, in which data is actually recorded to properly power the study. I would think that the presence of a dive buddy, and whether it is a regular buddy or not, is one of the more common variables since a.) most people do dive with a buddy and b.) there are are only possibilites, if they were with a buddy, - yes (instabuddy) or no (regular dive buddy) (without getting into further subdividing into how many dives they did together, as then I think it would be hard to properly power the study.

 

[kmarks]

I teach the CESA horizontally but think doing it vertically is exceptionally nuts given the damage it can and has done to students and instructors.

We teach the vertical ESA (SSI's term - apparently we don't care about control?) from our training platform at 12-15 feet. It's not super realistic, being only as deep as a shallow safety stop, but the idea is to demonstrate that the air expanding in your lungs as your ascend will make it much more comfortable than you think, but also limits the danger.

Which I personally believe is a complete waste of time. Doing a simulated CESA horizontally gives a completely wrong impression of how it will be if you have to do a real CESA vertically.

But what do I know? I'm not a certified instructor.

I agree that horizontal is basically a waste of time. I feel like it only teaches students that the (C)ESA is going to be difficult. No matter how many times you tell them that it will be different if they are doing it vertically, if they only do it horizontally, they will learn that it is difficult to swim slowly across the pool on one breath and that means the (C)ESA must be difficult.

Or . . . it teaches them how far they can go (frequently the length of a pool or 75 feet) exhaling on one breath without running the risk of them embolizing while doing it. And then you add in an explanation that, should they have to do this for real, gas expansion in their lungs while ascending will make it seem "easier" and even extend the range over which they can do this, thereby giving them some back-of-the-brain confidence that, should they ever have to do it for real, might kick in and save their life.

But what do I know? I AM a certified instructor and have been teaching for 40 years.

With fins on, going like a bat out of hell, yeah, I can easily cross an olympic pool in one breath. But that's not how you do a "safe" (C)ESA. Do it that fast from depth and you're not likely to survive; you might as well have dropped your weights and gone buoyant. When we did the CESA horizontally in my PADI class, we had to do it slowly and in one breath, across 40 feet or so. It was hard for everyone and when we did it vertically, from that shallow platform, it was hugely different. The horizontal experience did not translate to the vertical experience, but everyone wanted to swim to the surface as fast as they could because we all had the memory of how painful it was to swim across the pool on one breath.

Panic kills. They say we either respond to threats with flight or fight, but I think fright needs to be added. People often freeze when they are under threat of death. Unfortunately, it's high on impossible to teach people how to mitigate panic.

Were you ever in the military? (Honestly asking, it seems there is a large minority of us on Scubaboard who are veterans) The best way to teach how to mitigate panic is training and experience. Ask any first responder or veteran what happens when the SHTF and they will almost all say something to the tune of "that's when the training takes over." If your caravan gets hit by an IED and you start taking fire, your first thought would be to flip out and lose control if not for the training. By the time you deploy, you've gone through the exercises so many times that even if it's not exactly the same, you basically have a mental checklist that tells you what to do. Stop, think, act. Form a defensive box, find out where it's coming from, assess personnel/equipment, etc. You don't have time for panic if you have a checklist to follow and actions to take.

 

[Ken Kurtis]

We teach the vertical ESA (SSI's term - apparently we don't care about control?) from our training platform at 12-15 feet. It's not super realistic, being only as deep as a shallow safety stop, but the idea is to demonstrate that the air expanding in your lungs as your ascend will make it much more comfortable than you think, but also limits the danger.

Physics (and calculus) lesson of the day: Actually, it doesn't.

The greatest rate of change is happening the closer you get to the surface. Essentially, the danger increases as you get closer and closer to finishing the drill. You can embolize on a full lung (and holding your breath) in 4 feet of water. 12 feet is 1.36ATM. Ascending from "just" 12 feet still means you lungs will undergo a fairly large volume increase if you inadvertently hold your breath. You're definitely in embolism territory.

With fins on, going like a bat out of hell, yeah, I can easily cross an olympic pool in one breath. But that's not how you do a "safe" (C)ESA. Do it that fast from depth and you're not likely to survive . . .

Also not true. They is blowing off a volume of air equal or greater to the amount that's expanding. Boyle's Law. Sure, going faster is riskier because there's more rapid air expansion - again, especially as you approach the surface - but to make a blanket statement of "you're not likely to survive" is simply not true.

 

[kmarks]

Physics (and calculus) lesson of the day: Actually, it doesn't.

The greatest rate of change is happening the closer you get to the surface. Essentially, the danger increases as you get closer and closer to finishing the drill. You can embolize on a full lung (and holding your breath) in 4 feet of water. 12 feet is 1.36ATM. Ascending from "just" 12 feet still means you lungs will undergo a fairly large volume increase if you inadvertently hold your breath. You're definitely in embolism territory.

That's why I said it limits the danger, with an emphasis in limits.

Also not true. They is blowing off a volume of air equal or greater to the amount that's expanding. Boyle's Law. Sure, going faster is riskier because there's more rapid air expansion - again, especially as you approach the surface - but to make a blanket statement of "you're not likely to survive" is simply not true.

There are more concerns than embolism or lung over expansion if you are shooting from 60 feet to the surface in under 10 seconds.

 

[Ken Kurtis]

There are more concerns than embolism or lung over expansion if you are shooting from 60 feet to the surface in under 10 seconds.

What the hell, I'll bite . . .

And what exactly would those greater concerns be???
(Bearing in mind that an embolism stands a pretty good chance of killing you fairly quickly if a chamber is not readily available.)

 

[kmarks]

What the hell, I'll bite . . .

And what exactly would those greater concerns be???
(Bearing in mind that an embolism stands a pretty good chance of killing you fairly quickly if a chamber is not readily available.)

Poor editing on my part. I meant to say "greater concerns, like embolism, than lung overexpansion..."

 

[Ken Kurtis]

Poor editing on my part. I meant to say "greater concerns, like embolism, than lung overexpansion..."

I'm really not trying to slap you too hard here but you do realize that lung over-expansion IS embolism, yes???
In other words, if you embolised, it's because your lung (more correctly the alveoli within your lung) over-expanded, releasing air bubbles into your bloodstream.
And if you didn't embolise, it's because your lungs/alveoli didn't expand beyond their maximum capacity, so no emboli were created in the process (or lack thereof).

 

[kmarks]

I'm really not trying to slap you too hard here but you do realize that lung over-expansion IS embolism, yes???
In other words, if you embolised, it's because your lung (more correctly the alveoli within your lung) over-expanded, releasing air bubbles into your bloodstream.
And if you didn't embolise, it's because your lungs/alveoli didn't expand beyond their maximum capacity, so no emboli were created in the process (or lack thereof).

That's not the only way to form an embolism, but fine. You win. You're way smarter than I'll ever be. I'll quit this conversation.

 

[The Chairman]

It's not super realistic,

I agree that horizontal is basically a waste of time.

Both can be a waste of time, depending on the instructor. Neither are realistic... not even a little bit. Both allow you to teach technique. Only one is repeatable with no increased danger so the technique can be truly mastered. Only one entails no danger of embolism or barotrauma.

Were you ever in the military?

I proudly didn't serve. I was first taught by a Master Chief back in '69, for whatever that's worth. Wasn't much of a class and didn't involve anything to do with panic. The agencies stopped "harassment drills" early this century. That was a great tool, but some instructors went overboard with it and students got hurt. I don't get a lot of time with my students, so I use my time wisely. It's been my experience that many divers seem to be in a mild state of panic from their first immersion until they get on the boat. They lack a modicum of trim and buoyancy control and spend the entire time trying to correct it. They either look like rototillers or yo-yos and it's no wonder they lose their buddies or run out of air. They are task overloaded just by not being in control. So, I find it far more effective to teach control from the onset. Relaxed divers have the time and mindset to actually look at their gauges so they don't run out of air. They even look at their buddy's air and vice versa, so it's really effective in that regard. Fortunately, we don't deal with those pesky IEDs. Most, if not all, of the issues we encounter underwater are diver generated.