The straw that broke the divers back.

[bleeb]

Indeed, a diver who is physically fit can process more fuel and produce more CO2 much faster than one who is not. On a rebreather that fit diver can overload a scrubber much faster than the diver who just can't exert as much effort.

I think you have it backwards.

A fit diver will not exert as much effort as a diver who is out of shape/obese/not used to the physical work in ivolved in diving. Take two guys, one who is an athlete and one who is a couch potato and have them run a lap on the local track. Who's gonna be breathing faster when they make it back around?

The fit diver might not even break a sweat or breathe any more heavily than normal while in a crisis, the nonfit diver might be blowing through his air supply like there's no tomorrow. And for him or her, there's a good chance there won't be.

Of course, the practical reality is somewhere in between.

A fit diver is more efficient than an unfit diver, producing less CO2 per unit of work.

But a fit diver may also have the capacity to achieve a much higher peak power output, which is what overloads the scrubber.

 

[idocsteve]

Of course, the practical reality is somewhere in between.

A fit diver is more efficient than an unfit diver, producing less CO2 per unit of work.

But a fit diver may also have the capacity to achieve a much higher peak power output, which is what overloads the scrubber.

But now you're altering the conditions that the two hypothetical divers are working under.

The idea is that an obsese, out of shape diver, will not perform as well and may overbreathe his scrubber, as would a fit diver.

Now you're saying, well, the fit diver can work much harder and therefore may overload the scrubber. That's another whole variable introduced to the equation.

Back to the original premise, which I appear to be correct about:

While doing an identical dive, one where a crisis occurs such as a strong current or other emergency requiring above average physical exertion, the fit diver will be much less likely to over breathe their closed circuit rig than will an obese out of shape diver.

Fair enough?

 

[deco_martini]

I am a wimpy warm water diver. Last labor day my dive buddy and I went to North Carolina and dove the Spar. The water was calm and walm, and the sky was mostly sunny. My spider sense first startled tingling though when the captain took 10 minutes to hook onto the wreck. 5 feet beneath the surface was a current that was so ripping it made my regulator burp. We were flapping on the anchor line like flags. My dive partner is 170 pounds at 5'8" and I was at the time 5'8" 200.

10 feet down, struggling just to get down to the wreck, we were both in the first stages of panic due to exertion. We gave each other signals, went back up (not uncontrolled). Got a breather, and decided to try again but just go hand over hand back down to the wreck (finning down was what winded us, and the current pushing our regs to belch on top of what starting to tingle that "i cant get good air" sense).

Take 2, we get down to the wreck, hold onto it for dear life, see the sharks. Normal dive.

In retrospect, that dive was starting to sound like a "Lessons for Life" from a scuba mag early on. When we got back to our hotel that day, we basically passed out from exhaustion. Neither of us was "obese" on the BMI scale, but neither of us had good cardiovascular fitness. With the kind of martini diving we were used to, we had never realized how badly we needed it.

"Someone said fitness doesn't matter in diving until it does."

That is the truth. Worse, people build up confidence in places with less variable conditions and then maybe their first time diving somewhere wilder, they get the "worst day in 5 years" there. Its a recipe for disaster.

2 days ago at the health club (I hit the gym 5-6 days a week now after I learned a hard lesson in NC), I saw a new club member who was 35-45, 175 pounds maybe, 5'9", and he passed out during his cardio fitness test! Its not the obesity, although obesity usually is a positive indicator for it.

Guy at work, 42 years old, 5'8", 180, goes to his doctor for a physical and winds up admitted into the hospital for a quadruple bypass. Turns out he lost the genetic lottery for heart disease as his diet/etc wasn't bad.

So yes, fitness in divers is something I think about often, especially reading the DAN report for 2008 which profiled the average fatality as being 40-60, overweight, with significant reduced arterial flow.

Now, I love easy diving in places like the Caymans and Coz. I get my zen on underwater. I'm cool. However, I still remember on my first trip to Coz (non-diving trip with my wife), a diver at our resort had a cardiac arrest on his first dive. 50-60 years old, overweight, etc, etc. He fit the profile. It doesn't take a wild day in the Gulf or Atlantic to push an unfit diver over. It can happen on the bunny slopes too.

If you love to dive, and you love your family, get physical (or get a physical). It will cost you less than it will cost them in burial expenses.

 

[116fire]

I'm starting to feel like Jack Nicholson from A Few Good Men:

You don't want the truth because deep down in places you don't talk about at parties you want me on that wall, you need me on that wall. We use words like honor, code, loyalty. We use then as the backbone of a life trying to defend something. You use them as a punchline. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the blanket of the very freedom I provide and then questions the manner in which I provide it. I would rather you just said "thank you," and went on your way...

He he.

So:

You starrt off fine, but definitely go overboard on the degree of ability you recommend. A 550 under 10 minutes just ain't gonna happen for many folks, regardless of fitness. Especially for those of us that learned to swim at age 52. I'm happy with a 450 under 10. Multiple 25 yards underwater on 1 minute intervals? Ain't gonna happen for most people.

Its the journey that counts. Congrats on your 450 in ten. The underwaters repeats are with fins on sorry. Again though its the process. Knowing how it feels to be tired and out of air, but finishing anyway.

Why do you assume that the diver was out of shape? All we know really is that he is dead. He may have been a marathon runner and he is still dead. I agree that you should take care of yourself but in the end, you still die...at least that is what historical evidence has suggested.

Please I really though I went out of my way to not make it about a specific incident. Especially somebody who recently died. I don't know the specifics and I am deeply sorry for his friends and family.

I am trying to point out that all things being equal, one is more likely to survive a mishap if you are in better shape.

Note also part of fitness is health. In my opinion if you are doing any serious diving you should have a physical once a year, and a stress test every now and then.

What do you base this statement on? In the "VAST MAJORITY" of dive related deaths we can attribute people not being in good shape?

This IS news.

Do you have any statistical data to back this up?

What I said was: Most diver mishaps are a chain of mistakes and equipment failures. And in my opinion, in the vast majority of them better fitness would have helped.

The first sentence is almost a definition. The only ones that aren't go something like, bob jumped in and had a heart attack. Or then the shark eat him. But even those are the result of a chain of mistakes. Going diving where you might be eaten for example.

This is based on study reading and training. But very quickly: Most mishaps involve Panic. This is a mental and pysiological state. Mental state is effected by the state of your body. Hold your breath until its uncomfortable. Then try doing something intricate like some math problems on paper. Not so easy. The state of your body is effected by the state of your mind. What do you think the pulse rate is of somebody with their neck in the noose about to be hanged (hung?). Even if they are not exerting themselves at all. I will guess that somepeople even have a heart attack while they are waiting to be hung. But the noose is what kills them.

Ditto the hypercapnia. If your heart explodes in 30 sec, instead of passing out in 1 min, you have 30 sec less to fix the problem.

I survived a CO2 hit on a rebreather. All of a sudden my breathing went though the roof, and I thought I was going to die. The only reason I survived was I had heard a story of a friends experience. He said "I was breathing so hard and so paniced that it was all I could do to close my mouth piece, and put my bail out reg in my mouth" I grabbed a boulder--I was at about 150' in a quarry. And used all my will power to close my DSV, and stick my bailout reg in my mouth. My bouyance was going to hell, and I then had to battle to vent my drysuit, wing, and rebreather. All the time wondering if this was how I was going to die.

Better fitness means more bullets under extreme stress. Again if my heart had exploded, or if I couldn't keep it together to do the two things I barely managed to do--Get on alternate source of air and grab a rock--I probably wouldn't be here to irritate you today.


Its always better to be smart enough to stay out of trouble, than fit enough to fight your way out.

But like the old western:
They weren't looking for trouble, but trouble came looking for them.

Stay safe.

 

[bsee65]

Back to the original premise, which I appear to be correct about:

While doing an identical dive, one where a crisis occurs such as a strong current or other emergency requiring above average physical exertion, the fit diver will be much less likely to over breathe their closed circuit rig than will an obese out of shape diver.

Fair enough?

Don't confuse size with fitness. You can have great aerobic fitness and muscle tone under significant excess weight and do a lot better than the typical "healthy" person.

 

[zaberman1]

look, everyone on this thread has a lot of great points and I think they are worth taking into consideration. I do have one bone to pick:

PADI dream world? Seriously!? To say that divers need to be responsible and follow the rules is one thing but to start agency bashing and blame the problem on the big box corporation is another. Yes, PADI may be an easy target, but to blame this agency for the problem we have in the diving community is both unproductive and wrong. Come on, focus on the substance....

 

[idocsteve]

Don't confuse size with fitness. You can have great aerobic fitness and muscle tone under significant excess weight and do a lot better than the typical "healthy" person.

Seems highly unlikely if at all possible.

Either you're in good physical shape with great aerobic fitness and muscle tone OR you're an obese out of shape couch potato.

How can you be both?

 

[OldNSalty]

Seems highly unlikely if at all possible.

Either you're in good physical shape with great aerobic fitness and muscle tone OR you're an obese out of shape couch potato.

How can you be both?

Common misconception; I have known a lot of flabby people who insisted that their large size was muscle and felt they were in great shape. Not saying that the OP is this type of person, just something I’ve noticed in general.

 

[N2BLUE]

This recent tragedy warrants examination for sure, not for finger pointing but more introspective, "How can I learn from this incident?" type of analysis. I am an Instructor and Dive Master in Pensacola and run trips to the "O" frequently. Fortunately, in over two hundred 'working' dives on her, I record only one, "Aww, *****!" that was remedied by the diver. That diver was on a rebreather. After recovering and back safely on the boat, my British friend patted his RB and quipped, "Yep, about once a year or so she tries to kill me." Of the deaths of divers on the "O", the commonality was a rebreather. Just saying. Yes, fitness and skill proficiency are VERY important, however, let us not use this tragic event to overlook the obvious. There is a reason crews refer to a RB as a, "little box 'o death". I know that pisses of some, but I think it's only fair since this was introduced via the death from the Oriskany this past weekend.

 

[DennisS]

Seems highly unlikely if at all possible.

Either you're in good physical shape with great aerobic fitness and muscle tone OR you're an obese out of shape couch potato.

How can you be both?

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