@
raftingtigger: Thanks for sharing your thoughts on the incident. You bring up a lot of good points. One of the things that, in my opinion, makes a good dive pro (DM/AI/instructor) is approaching instruction in a thoughtful way. I get the feeling you're going to do that.
I was trained in buoyant ascents (drop weights at the bottom), but that was in 1973. Many of the posters are making recommendations, but fail to give their qualifications. While I'm not going to make any recommendations in this post, my qualifications are: I'm currently a professional healthcare provider (Physician Assistant in Urgent Care), former Airline Captain (and check airman), ALPA safety committee member with extensive accident and safety training, Flight instructor for many years, former Paramedic, professionally trained Whitewater rafting guide, Swiftwater rescue and Rescue Diver trained. From this vantage point I have a few comments.
I'm
not going to assert this in your case, but I've found that the people on any Internet forum who claim authority through certifications, education, or experience, appear rather insecure about the comments they are making. Any thinking, rational human being will be able to read a post, judge the words on their own merit, and appreciate (or not) the author's perspective. FWIW, I'm not a dive pro, and, therefore, I have no formal experience teaching scuba divers. I'm just an average recreational diver with some rescue training.
5. Both young men in this tragedy were NEGATIVELY buoyant at the time they were found – else why were they on the bottom.
Most novice divers whom I encounter are negatively buoyant at any given point on a dive. They are kicking along at an angle (45°?) with the ocean bottom (head-up/feet-down trim). If they stop kicking, they will sink.
6. To paraphrase a 1991 Monterey Diving guidebook: The 23 dive fatalities in the last 20 years (numbers are my best recollection) ALL (my emphasis) had their weight belts on. I do not know if this applies from 1991 to present, but according to our PADI instructor he believes it still does. This is a POWERFUL statistic in my mind.
I'd like to caution you about reading too much into that 1991 report. Your interpretation would seem to suggest that failure to ditch the weightbelt contributed to one or more of those 23 fatalities. Wouldn't it make sense to do an in-depth accident analysis of each specific case...and
then draw a conclusion about whether failure to ditch weight contributed to death? After all, correlation does not imply causation.
8. A BCD cannot be inflated underwater if the tank is empty - either by the power inflator or by mouth.
From this statement, you seem to be implying that ditching weight is the only way for a diver with an empty tank to ascend. If a diver wants to ascend to the surface from any depth, why should he ever have to
add air (by power inflater or by mouth) to his BCD? A small kick up should initiate an ascent very easily -- air expands in the BCD and neoprene expands as the ambient pressure decreases. Perhaps divers need to learn how to be "neutrally" buoyant at depth. That's something I learned in my PADI basic OW class.
9. I know of only two ways to make a negatively buoyant object into a positively buoyant one. Either increase displacement (ie add air into a BCD) or decrease density (ie drop weights). This is physics.
Don't forget that as you ascend your wetsuit will expand a little as ambient pressure decreases. Also, as you use up air from your tank, this should make you more "positively" buoyant. Obviously, if the tank is already empty, the latter effect doesn't occur in any significant way.
10. Dropping a weight belt does not have to mean dropping all your weights. There is a big difference in dropping a 10-15# belt and a 25-40# belt. This thinking is changing how I'm going to rig my personal (and family) gear. BCDs will carry trim weight, use of ankle weights, and keep the actual ditchable weight belt to a reasonable weight, but one that allows positive buoyancy at any planned depth by its removal. I have discussed this with our PADI instructor and he agrees.
If you or the divers in your charge decide to wear a weightbelt with a weight-integrated BCD, please let the boat crew know about this weight configuration ahead of time. I had an interesting conversation with a very experienced Monterey boat captain who thought splitting up weight in that way was dangerous. (I strongly disagreed BTW.) He shared a story in which he was trying to get a panicked diver back on board his boat. Apparently, he removed the diver's weight-integrated BCD...and the diver immediately began to sink because he was also wearing a heavy weightbelt (apparently counteracting the positive buoyancy of his exposure suit). Fortunately, the captain had a strong hold of the diver and there was a good outcome. The take-home message for me from this story was that the boat crew needs to know
how you are carrying your weight. I won't get into who I thought would be responsible if something bad had happened to that panicked diver.
11. You can't hurt a dead person. Drowning IS DEAD ("near drowning" is different), AGE, other lung overexpansion injuries, and DCS while they can cause death, are often treatable.
I'm not sure where you're going with this statement. In any emergency situation, if you can help out in a way that has an acceptable level of risk to you, choose the approach that will result in the best outcome for the victim. If that means getting the diver expeditiously to the surface (and often times it does), figure out a way to do that.
