Learned Wrong...

[Thalassamania]

I have seen numerous cases where there was an empty tank at the end of an incident but not at the start of the incident. One that sticks in my mind was a case where the diaphragm in the second stage did not seat and flooded the regulator, the diver aspirated water, induced freeflow in his octopus, and bolted for the surface suffering an embolism. When the tank was finally gauged, it was all but empty.

 

[Akimbo]

It is very common to see empty tanks on a recovered corpse. Very often the remaining pressure is lower than a human could have sucked it down before passing out, which indicates post mortem leakage. It is also quite common to find the body after the mouthpiece has fallen out. An empty tank only indicates that they were empty when found, but is not a reliable indicator that low air played any role in the tragedy.

Many high performance regulators will freeflow when the second stage falls out of your mouth. Some medical conditions that are difficult to impossible to detect on a deceased diver can cause loss of consciousness yet automatic breathing does not stop. It may be reasonable for a coroner to list loss of air as a “probable” cause of death, but accident analysis needs to look much deeper if lessons are to useful.

 

[tflaris]

I'm still unclear what you meant by, "I have yet to hear an intelligent reason why this is not a valid safety option for all other divers..." I can give you lots of intelligent reasons why a diver - ANY diver, not just saturation divers - should not ditch their weight. Would you like to hear them, or did I misunderstand your statement?

I found this article online:

http://www.divingmedicine.info/divingmedicine/Welcome_files/Ch 34 SM10c.pdf

It was an interesting read.


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[Thalassamania]

I found this article online:

http://www.divingmedicine.info/divingmedicine/Welcome_files/Ch 34 SM10c.pdf

It was an interesting read.


Sent from my iPhone using Tapatalk

I often have quibbles with Carl, but generally his stuff is worth reading. Here's the link to the entire book: Diving Medicine for SCUBA Divers

 

[boulderjohn]

This sounds a lot like GUE or UTD philosophy? ...

Also, when my wife got certified in 2010 (I got mine in 1976), I believe the "learned wrong" was not drilling repeatedly on in-pool or in-ocean exercises such as a "surprise" shutting off the air and having her re-oen her valve, not enough buddy breathing practice, no drills such as doffing and donning your gear with your mask off, diving with your mask off, etc. We even had to turn off our valves so we would know what running OOG felt like and then turn them back on.

This is the fault of the new e-learning procedures and limited pool and open water sessions. I know that "old school" can seem macho, but I really believe those elements of my training were invaluable.

What does eLearning have to do with this? That only involves the academic learning and has nothing to do with the pool and open water training. And, by the way, UTD uses online learning, too.

 

[Thalassamania]

If nothing else, e-learning cuts down on the contact time between the instructor and student; that is, sort of, the objective, is it not? Now, I realize that in the case of some instructors that may be a good thing, but for others it removes get to know each other time and establish credibility and trust time. A plastic card and a patch jacket does not, in and of itself, or in combination with a DVD player, create (at least for me) any of the warm-fuzzies that I think are core to teaching diving. But then, I rooted for John Henry.

 

[markmantei]

Not something I learned wrong, but something I saw taught wrong....

An AI was teaching some OW students about SAC rates. On the previous dive he had them calculate their resting SAC rates (sitting on the bottom, resting for 1 minute). He was now during their SI having them calculate their required gas for the next dive based on those resting SAC rates. :shocked2: To ignore rock bottom is one thing, but to instruct OW students who do not know any better to vastly underestimate gas consumption, and then plan dives on that faulty information (given that most of us do not own scooters and must actually "fin" to get anywhere on a dive) was ridiculously stupid and dangerous (not necessarily during the class, but for future dives conducted now with no safety margins). Not that I'm advocating it, but better to not teach SAC's at all and leave it at surface with 500psi.

 

[boulderjohn]

Not something I learned wrong, but something I saw taught wrong....

An AI was teaching some OW students about SAC rates. On the previous dive he had them calculate their resting SAC rates (sitting on the bottom, resting for 1 minute). He was now during their SI having them calculate their required gas for the next dive based on those resting SAC rates. :shocked2: To ignore rock bottom is one thing, but to instruct OW students who do not know any better to vastly underestimate gas consumption, and then plan dives on that faulty information (given that most of us do not own scooters and must actually "fin" to get anywhere on a dive) was ridiculously stupid and dangerous (not necessarily during the class, but for future dives conducted now with no safety margins). Not that I'm advocating it, but better to not teach SAC's at all and leave it at surface with 500psi.

Did you see all of the instruction? Some people use terms differently, and are you sure what was done in this case?

For many people, SAC rate is indeed a resting, non-active, surface rate. The rate is then used to estimate gas usage by multiplying by expected pressure at depth and a number representing an anticipated activity level. This is called RMV--Respiratory Minute Volume.

Other people use the term SAC to refer to a rate that includes the expected activity. If most of your dives are at about the same activity level, that is the easier way to do it, but it is not the only way to do it.

 

[Akimbo]

I often have quibbles with Carl, but generally his stuff is worth reading. Here's the link to the entire book: Diving Medicine for SCUBA Divers

There is a great quote I suspect we both agree with:
Diving Medicine for Scuba Divers 3rd Edition 2010
Chapter 34 — 5

Earlier diving instructors taught that the weight belt was the last item put on, the first taken off. It was to be removed and held at arm's length in the event of a potential problem. The diver then had the option of voluntarily dropping the belt if the situation deteriorated, or replacing it if the problem resolved. When problems did develop, the belt was dropped automatically! Some current diving students now question the validity of dropping these lead (? dead) belts – perhaps the high cost of replacement is worth more than their lives. "Lead poisoning" is a frequent contribution to fatalities.

This is the most rapid-acting and deadly form of Lead Poisoning I can think of.

 

[markmantei]

Did you see all of the instruction? Some people use terms differently, and are you sure what was done in this case?

Yes, I was there for all of the instruction (was also on my SI during rescue training). This particular individual had some very rudimentary and dangerous knowledge of appropriate gas usage and reserves. I recall having a very interesting discussion with this gentleman the previous day while waiting for tank fills. While I don't recall all of the details, it definitely had to do with dives he had done with vastly insufficient gas reserves, and I suggested at that time that he google rock bottom. His dive count and experience were below mine as well, not that I am implying that I am in any way experienced, but this goes to show the folly in taking courses without appropriate diving experience and a method to validate instruction mixed in. This goes doubly for those instructing others who cannot be expected to know better. SB should NOT be used as the only method for gaining knowledge, but it sure will let you know when something you have learned is wrong (not always kindly ).