Number one cause of diving fatalities?

[boulderjohn]

In an emergency, people behave the way they are trained. They are not trained to drop weights. They are trained to pretend to drop weights and warned to not actually do it except in an actual emergency.

So because the instructors in your class did it a certain way in violation of standards, that must be what is happening all over the world, right? Believing that something you have not seen must not exist is borderline solipsism.

 

[2airishuman]

I sometimes question even having an extra second stage regulator. To play devil's advocate: If you are at 90 ft, you have 700 Lbs. and someone runs out of air because he did not watch his gauge, will you share your precious air with him? Will you look at your gauge and think "Wait a minute; he should do a free ascent."

I will not be found at 90' without either a twinset or a pony, and I will not be found at any depth beyond 20' without the air and equipment necessary to bring an OOA diver to the surface, regardless of whether or not I think I'll encounter another diver.

 

[2airishuman]

So because the instructors in your class did it a certain way in violation of standards, that must be what is happening all over the world, right? Believing that something you have not seen must not exist is borderline solipsism.

John.

I don't believe for a minute that my experience is universal. Neither, however, do I believe it to be so isolated an experience as to be irrelevant to this discussion.

Neither of us knows how every instructor teaches.

I had two instructors, 2000 miles apart, one in the pool, one in the ocean. So I can share my statistically insignificant experience of 100% in a sample size of two.

I think that this skill should be taught so that the student is performing it exactly as they would in an emergency at the surface. They should go through all the motions with the intent of getting free of the weights without regard to where they end up. That's the way you build psychomotor associations. If the instructor catches them, fine, but the student shouldn't adjust the skill so that having the instructor catch them is part of the goal.

And I understand that that's how you're teaching it. And I accept that it's part of the standards to teach it that way. I believe there are many instructors who teach it that way. There are some instructors who do not.

 

[2airishuman]

There are many reasons for fatalities, and dropping weights is not a factor in the overwhelming majority of them. For example, in the most common fatality event, if someone passes out from a sudden cardiac event, they do not have the opportunity to do so. You can't drop your weights when you are already unconscious or already dead. In response to a discussion of this ilk several years ago, I went through the descriptions of fatalities in two years of DAN fatality reports. In each year, I found only a handful of cases in which dumping weights MIGHT have made a difference in the outcome of the incident. I included in that total any incidents in which there was even a remote possibility of a different outcome. In over 90% of the cases, the fact that the diver did not drop weights was irrelevant to the outcome--it would have made no difference.

Somehow people get the idea that all fatalities could be prevented by dropping weights.....

I agree with you on all this. I think that ditching weights as a conditioned response is mainly useful when a diver reaches the surface after an OOA emergency or buoyancy failure. As I recall there's a small but significant share of fatalities that occur after a diver has safely reached the surface. Perhaps it's 10% or less.

 

[boulderjohn]

I agree with you on all this. I think that ditching weights as a conditioned response is mainly useful when a diver reaches the surface after an OOA emergency or buoyancy failure. As I recall there's a small but significant share of fatalities that occur after a diver has safely reached the surface. Perhaps it's 10% or less.

There have been a couple of cases--really only a few--in which divers reached the surface after an OOA incident, failed to achieve buoyancy, and then dropped back down. It is nowhere near 10% of fatalities, but it has happened. As a result of this revelation in their study with DAN, PADI made two adjustments to their OW course several years ago:

1. Adding the aforementioned requirement to experience a weight drop at the surface.
2. Adding an OOA ascent with oral BCD inflation after a deep pool OOA skill.

In reality, there is a third skill involved in achieving buoyancy after an OOA event--proper weighting. In the class, students are taught that proper weighting is achieved when they float at eye level with an empty BCD while holding a normal breath. This test is done with a full tank, and some people advocate adding extra weight to compensate for anticipated loss of the weight of the gas. Some people do not advocate that, saying that at the beginning of a dive, there is enough trapped air in the gear to make that difference.

If a person does indeed float at eye level with a full tank and en empty BCD, how on Earth is that person sinking with an empty tank and the air that was in the BCD during the dive, air that expanded and made the diver more buoyant upon ascent? Even if the person added enough weight to compensate for that anticipated air loss, that person should be able to stay afloat with lazy kicking. Only a heavily overweighted diver should be unable to stay on the surface with an empty tank.

 

[kelpqwest]

If you are neutral at the surface with your gear on, do you have a problem using a snorkel without ditching your precious weight? No, you are fine.

The instruction of diving with too much weight is: 1. inherently dangerous 2. unnecessary because you can swim down with your fins 3. wetsuit squeeze means you can actually be positive at the surface and will be neutral at depth (this takes figuring your weight from a dive or two). 4. more weight+partially inflated BC= you have more mass+more drag=you burn more air.

More mass means you will need to expend more energy to propel yourself through the water, it is irrelevant if you are neutrally buoyant.

 

[Storker]

As I recall there's a small but significant share of fatalities that occur after a diver has safely reached the surface. Perhaps it's 10% or less.

Judging from what I've read about fatalities around here the last years, that share is at least 10%. If not quite a bit more.

 

[kelpqwest]

From chapter 34 of Diving Medicine "Why divers die"
Overview
Diving Fatality Data
90% died with weight belt on
86% were alone
50% did not inflate BC
25% had first difficulty on the surface, 50% actually died at the surface
10% were under training
10% were told they were medically unfit
5% cave diving
1% "rescuers" became victim
Those are just results, to study the causes there is other information.

For example, difficult surface conditions (e.g. Northern California) + too much weight+run out of air can be a difficult combination. You can be negative at the surface, then unable to mouth inflate BC or forget to ditch weights while struggling to breathe, etc.

 

[kelpqwest]

I will not be found at 90' without either a twinset or a pony, and I will not be found at any depth beyond 20' without the air and equipment necessary to bring an OOA diver to the surface, regardless of whether or not I think I'll encounter another diver.

I guess I don't get the concept of carrying 1. extra bottles 2. extra air for other divers to use.

The vast majority of my dives are 90 feet or shallower (deeper in California is actually much less interesting). I would become selfish of my air supply over 40 feet. I can free ascend from 60 with all my gear on because I have had to do it.

True anecdote: A guy off FL chasing lobsters ran out of air at 80+ ft. A PADI instructor handed him his pony bottle which did not function. So, the PADI instructor swam over to a new diver and grabbed her regulator and dragged her over to give her air to the careless lobster diver.

This could have resulted in drowning when the appropriate response would be tell the lobster diver "learn a life lesson from this; swim up yourself and have a nice day."

 

[boulderjohn]

90% died with weight belt on
...
50% did not inflate BC
25% had first difficulty on the surface, 50% actually died at the surface

Interesting stats when taken together. If they died at the surface, then taking the weights off or inflating the BCD would have made no difference in those cases.