Ascent Rates-Split from Catalina Diver died today

[Teamcasa]

The big problem (considering TSandM's excellent post) is not just a rapid ascent rate or holding your breath. We all understand that both are difficult for the human body to manage and the outcome differs for everyone.

The big problem is why you are holding your breath or ascending too fast in the first place.

When all conditions are normal, divers generally don't hold their breath or shoot to the surface. They do one or the other, or both, as a result of something going wrong combined with a lack of training and adequate practice time dealing with abnormal diving situations.

 

[Ken Kurtis]

Jim, I would hate for the measure of my teaching ability to rest on what any one of my students retained some point after my class. "I wasn't taught that" sometimes means "I don't remember being taught that"

The job of an instructor, IMHO, is to MAKE SURE they get it. Thats what teaching's all about. If they don't remember being taught something, and especially if there's some consistency with students forgetting X, Y, or Z, then maybe a re-examination of teaching techniques is in order.

One thing I do after each basic class I teach (and before I turn them loose) is go through all the final exams and see what questions were missed. If I've got a high percentage of students missing certain questions, that's probably more an indication that I didn't teach well rather than they were bad students. And so I'll review those points with the entire class before issuing cards.

"Presenting the information" is not the same as "teaching". It seems to me today (and this is not meant as a slam at wedivebc) that we have too may "Scuba Presenters" and not enough "Scuba Teachers."

- Ken

 

[DCBC]

The job of an instructor, IMHO, is to MAKE SURE they get it. Thats what teaching's all about... It seems to me today (and this is not meant as a slam at wedivebc) that we have too may "Scuba Presenters" and not enough "Scuba Teachers."

I agree Ken, but I think what wedivebc was getting at was that an Instructor can teach all the right things and time can pass and the diver forgets what he learned.

Wayne
NAUI 4728

 

[InTheDrink]

As a side note, I cringe anytime I see a smoker who dives. A smoker can be doing everything correctly (with regard to not holding his breath during ascent) and still be at very high risk of experiencing a lung overexpansion injury. With respect to lung overexpansion, smoking has a double whammy effect:

1. The tar in inhaled smoke paralyzes respiratory cilia which help move mucus up and out of the respiratory tract. This stagnant mucus becomes an obstruction hazard.
2. Inhaled smoke damages the walls of terminal airways, resulting in less tissue flexibility and the development of emphysema.

Even with an open glottis, it's easy to imagine how a mucus plug inside the lungs could trap air in the terminal air spaces. Upon ascent, the expanding air will find a way out -- possibly the weakened walls in terminal bronchioles and alveolar sacs. The result is a pneumothorax. And that's not the only reason to quit smoking. Carbon monoxide in inhaled smoke decreases the oxygen-carrying capacity of the blood. There's also the increased risk of heart disease and several types of cancer.

My point is...divers really should not be smoking. Sorry for going off on a tangent like this, but I think it is related to the topic of discussion.

I don't want to add to the thread hijack so maybe this should be posted separately but is there any data as opposed to theory that shows smokers are higher risk? I ask because I've come across a lot of DMs/Instructors/Guides that smoke. Admittedly this is often in poorer countries where smoking is more prevalent but it is certainly not exclusive to poorer countries. There's a lot of down time when diving - smoking is great at killing time (yeah, leave the obvious retort at the door ). Anyhow, main point being - is there any actual data showing smokers to be at higher risk of DCI?

J

 

[Blackwood]

The job of an instructor, IMHO, is to MAKE SURE they get it. Thats what teaching's all about.

And perhaps to identify those people (if possible) who are prone to panic and advise they take up a different hobby (even if doing so hurts the bottom line).

 

[herbdb]

The job of an instructor, IMHO, is to MAKE SURE they get it. Thats what teaching's all about. If they don't remember being taught something, and especially if there's some consistency with students forgetting X, Y, or Z, then maybe a re-examination of teaching techniques is in order.

One thing I do after each basic class I teach (and before I turn them loose) is go through all the final exams and see what questions were missed. If I've got a high percentage of students missing certain questions, that's probably more an indication that I didn't teach well rather than they were bad students. And so I'll review those points with the entire class before issuing cards.

"Presenting the information" is not the same as "teaching". It seems to me today (and this is not meant as a slam at wedivebc) that we have too may "Scuba Presenters" and not enough "Scuba Teachers."

- Ken

Wow!! I sure generated a lot of hostility with my question. Perhaps it was the phrasing.

Of course, my instructor taught me how to ascend from a dive and made sure I know how to do it properly.

The question was when does it become dangerous to deviate from the recommended rates?

For those who were civil and thoughtful with the responses, Thanks!

For the rest Well...........

 

[Thalassamania]

Three thoughts:

First, on ascents ... the ascent rate is built into the decompression calculations, the slower the ascent rate the longer the no-D time on the table. You can ascend rather fast (submarine escape is done at about 350 fpm) without decompression problems assuming the pressure exposure is short enough.

Second, on embolism ... this is not speed dependent, this has to do with not having an open airway as the gas in your lungs expands due to a drop in external pressure.

Third, concerning teaching ... if they have not learned, have you taught?

 

[DCBC]

...concerning teaching ... if they have not learned, have you taught?

If they have not learned, they should not be able to pass the exam. If in-time they forget what they knew, that's not the fault of the Instructor.

For example, I've forgotten most things from my organic chemistry class covering the acidity of organic acids. Since I passed the exam, the university said I learned enough, so I can conclude that I was taught correctly. Learning retention and memory may well be a different beast.

How long should a human being remember what s/he knew, when they don't use the information learned in everyday life?

 

[captain]

I was told do not ascend faster then your bubbles.

Actually the old rule was don't ascend faster than your "smallest" air bubbles.

 

[AfterDark]

Actually the old rule was don't ascend faster than your "smallest" air bubbles.

Funny how that worked all those years for so many people but today it's akin to witchcraft. I don't get it? Does anyone know what that rate of ascent would be?
Dare anyone risk their life trying it?:shocked2: