Teaching contradictions: differing dive training philosophies

[Thalassamania]

Pete:

I'd appreciate a medical reference that indicates the level of nitrogen load and an indication of the depth that repeated ascents at 60 fpm to the surface followed by descents present a problem. My understanding, open to correction by creditable sources, is that bubble pumping involves ascent from dives somewhat deeper than those depths that are agencies specify for CESE practice (typically shallower than 30 feet) and involve a diver with a a nitrogen load sufficient to cause venous side bubbles that are picked off at the lung capillaries and that upon re-descent compresses sufficiently to move them through the capillary bed to the arterial side. Since a descent back to, say, 33 fsw only results in a bubble radius decrease of about a quarter, and since short dives in such shallow regions result in rather light nitrogen loads, I've got some doubt that there is a real issue here.

I'd also appreciate a medical reference to the cases of instructors injured during CESA evolutions. Unlike your anecdotal observation, the only injuries that I have observed instructors incurring during CESAs were minor ear problems that resulted in injuries that presented with no major acute injury and that resolved themselves in a matter of days, though long term "glue ear" is always a worry with any middle ear injury.

 

[The Chairman]

I'd appreciate a medical reference that indicates the level of nitrogen load and an indication of the depth that repeated ascents at 60 fpm to the surface followed by descents present a problem.

So would I. I suppose you have one that states that a 60 fpm ascent from 25 feet is a good idea, right? I actually teach that the final ascent should be less than 10 fpm. I wonder why all the agencies changed from 60 fpm to 30 fpm??? They should have asked you first, huh? Here's all DAN has to say about ascent rates: Divers Alert Network They say that "Most Experts" say that the ascent rate has an affect but we really don't have enough data. You should notify them that you disagree with this assessment and that all ascents from your safety stops should be at 60 fpm. After all, that's what you are teaching by example.

I'd also appreciate a medical reference to the cases of instructors injured during CESA evolutions.

So would I. Recurring ear problems are the most common that I have heard of. My NAUI CD, Wayne Mitchell told us that he had injured himself more than once doing multiple CESAs. He blamed his increasingly bad hearing to those injuries but old age certainly was a factor. But at least you admit that injuries occur during CESAs. Why expose ourselves to such nonsense? Can you provide a study showing that the risk of doing all these CESAs have saved even one life? Or, even better, that doing only horizontal CESAs has cost a life?

I said at the very beginning that the information that I had was anecdotal. I am not sure why everyone is asking me for something I never said I had? I was asked just this past spring to do a series of CESAs for an instructor out of Miami. Not could I not do them for him, as I was not an instructor for his agency, but I told him I would not do them for him. All of the instructors I refer to are from Florida. While I meet more than my fair share of instructors doing what I do, I really found it quite alarming. Consequently, I have shared that here. Accept it or reject at yours and other's peril. As for me, I'm not going to subject this 55 yo overweight body to the rigors of multiple quick ascents from any depth. Your perceived level of acceptable risk in this case may be quite different than me. I'm way OK with that. I don't possess the arrogance to believe that I can dive like Aquaman and get away with it all the time.

 

[DCBC]

I suppose you have one that states that a 60 fpm ascent from 25 feet is a good idea, right?

Our testing at DCIEM supported a 60 FPM ascent rate to 30 FSW, 30 FPM to 10 FSW and 10 FPM between 10 FSW and the surface. These figures have been modified somewhat depending on the authority. Regardless, we're spitting hairs. If you dive within the tables (especially with today's fudge factors incorporated into them) in 60 FSW. I know of no evidence that prohibits multiple ascents if they are done at a safe rate. This of course assumes that the diver is medically fit to dive. Obviously excess obesity and some other conditions should be taken into consideration. Personally, I have no problem diving on this schedule and have done so for over 40 years of recreational instruction without incident. I cannot understand why this would be demonstrating a "bad example" to my students, but am open to anyone sharing evidence to the contrary.

Pete, stating how you elect to dive and teach is up to you. It's a different matter if you criticize the practice of others unless you have the evidence to support your claim... Perhaps however, I'm misunderstanding something?

 

[The Chairman]

I cannot understand why this would be demonstrating a "bad example" to my students, but am open to anyone sharing evidence to the contrary.

I can't make you see something if you keep your eyes closed. You teach 60/30/10 fpm just as I do. Why? If you feel this is valid, then why suspend it for a simple stunt? Obviously, you teach horizontal CESAs and then you go to vertical CESAs. What do the students really gain one over the other? In fact, most everyone has suggested it's harder to do horizontally, so what's the big deal? Just to show them it's possible? If it's possible horizontally, then why is it questionable vertically? Now, they've just seen their instructor violate the 60/30/10 protocol several times on one dive. Would you call this a "good example" for them to follow? If so, then end the hypocrisy of teaching 60/30/10 and just teach 60. If not, then reconsider how you are teaching them.

Pete, stating how you elect to dive and teach is up to you. It's a different matter if you criticize the practice of others unless you have the evidence to support your claim... Perhaps however, I'm misunderstanding something?

That's just it. I have stated what I teach, why I teach that way and yet others call me to task for it. It would appear that they infer any variance from the way that they teach as a criticism. No, I haven't called them any names or indicated that they are poor instructors. No, I will not teach like they do, so shoot me. Never mind, they're doing that on their own already!

 

[DCBC]

I can't make you see something if you keep your eyes closed.

Open my eyes with science not opinion.

I can't make you see something if you keep your eyes closed. You teach 60/30/10 fpm just as I do. Why? If you feel this is valid, then why suspend it for a simple stunt? Obviously, you teach horizontal CESAs and then you go to vertical CESAs. What do the students really gain one over the other? In fact, most everyone has suggested it's harder to do horizontally, so what's the big deal? Just to show them it's possible? If it's possible horizontally, then why is it questionable vertically? Now, they've just seen their instructor violate the 60/30/10 protocol several times on one dive. Would you call this a "good example" for them to follow? If so, then end the hypocrisy of teaching 60/30/10 and just teach 60. If not, then reconsider how you are teaching them.

Pete, the rate of ascent is how fast you come up; the number of ascents made on a decompression schedule is the number of times you ascend. ROA is a fixed rate dependent on depth; the number of ascents either conforms with safe diving practice (dictated by the tables), or it doesn't. Why is it that you confuse the two?? I don't violate the recommended ascent rate and therefore don't demonstrate a bad example to my students. I always dive within the tables (although I may elect to do more than one ascent during CESA examination in OW).

Horizontal CESA is not the same as a vertical one for the reasons you've mentioned. Buoyancy changes and this can affect the ascent rate. This is part of the CESA and one that must be demonstrated.

That's just it. I have stated what I teach, why I teach that way and yet others call me to task for it. It would appear that they infer any variance from the way that they teach as a criticism. No, I haven't called them any names or indicated that they are poor instructors. No, I will not teach like they do, so shoot me. Never mind, they're doing that on their own already!

That is not my understanding. How you teach is between you, the student and the certification agency. Personally, I don't care what you do.

I believe however, that it was you who was suggesting that other Instructors were showing a bad example by undertaking multiple ascents for the purpose of CESA training. I maintain that multiple ascents can conform to good decompression practice and because of this, I've asked you to substantiate your claim. If you're claiming that some instructors dive outside the tables, that's a legitimate complaint. This doesn't mean than an Instructor who elects to do multiple ascents in OW, is acting in a unsafe manner and setting a bad example. That's crap.

I teach students to dive within the decompression tables. I don't make-up personal decompression rules that I expect them to follow (like one dive one ascent). I encourage them to know the science, to dive responsibly and apply good judgment. The Boogie Man will not get you if you dive within the tables, regardless of how many ascents you make from 60 FSW. Other considerations apply to depths greater than 60 FSW and are discussed in the Advanced Course..

 

[The Chairman]

Open my eyes with science not opinion.

Ditto. I'll even add logic and best practices. I see absolutely no science to support doing a vertical CESA.

Pete, the rate of ascent is how fast you come up;

Glad you figured that out. So, during a CESA you have your students abide by the 60/30/10 protocol? Interesting. I teach that a CESA should be at 60 fpm until you hit the surface. I think that 60 fpm should only be done when there is a much larger threat of drowning to be avoided. You would be the first person I have ever met to teach that students do their CESAs with a 60/30/10 protocol, if that's indeed how you teach it.

This is part of the CESA and one that must be demonstrated.

That's your opinion, now show me the science.

I believe however, that it was you who was suggesting that other Instructors were showing a bad example by undertaking multiple ascents for the purpose of CESA training.

I certainly believe that instructors set a bad example when they do this as well as kneeling to teach skills. That's why I don't do those practices. I'm genuinely sorry that you are taking this with such a think skin. To be clear, I never called anyone a "bad" instructor or other epithet for doing either, but I find both scenarios as being counter productive in the teaching environment. As I pointed out: it sends confusing and mixed signals about what is acceptable AFTER the class.

I don't make-up personal decompression rules that I expect them to follow (like one dive one ascent). I encourage them to know the science, to dive responsibly and apply good judgment.

For the record here... you don't believe in surface intervals between each and every dive (barring an emergency)? I think this flies in the face of our understanding of bubble pumping and violates almost every agency's imposition of a 10 minute minimum SI between dives. Or possibly, you are the one stretching the rules to fit your teaching style. That's up for you to decide. As for me? I'm going to set the best example as I know how to do during every single dive with every single student. I owe them that.

 

[DCBC]

...I teach that a CESA should be at 60 fpm until you hit the surface.

As NAUI's specifies a maximum ascent rate "no faster than 9 meters (30 feet) per minute," I follow policy when teaching a NAUI program. As you are a NAUI Instructor, if you're teaching 60 FPM, you are teaching in contravention of NAUI standards. Not to say that you're setting a bad example or anything Pete...

Obviously, the ascent rate matters little if the diver doesn't reach the surface. I ensure that the diver is aware that they are capable of reaching the surface at a normal ascent rate. This builds diver confidence. In any diver emergency, confidence can eliminate the desire to panic (which may be the natural reaction). That too is something that can be learned (if the Instructor has the ability and desire to teach it). I feel that I owe my students this.

That's your opinion, now show me the science.

You were the one expressing your opinion. I'm showing you the policy that NAUI established, based upon the science.

...I think this flies in the face of our understanding of bubble pumping and violates almost every agency's imposition of a 10 minute minimum SI between dives. Or possibly, you are the one stretching the rules to fit your teaching style.

Perhaps the problem is that you (for some reason or another) believe that a dive is completed (for the purpose of the tables) when you ascend (one ascent, one dive). This is NOT the case. When using the decompression tables, there is NO second dive until the surface interval is more than 10 minutes (NAUI recommends 60 mins. between dives). If any subsequent dive is undertaken in less than 10 mins., it is considered part of the previous dive and the time is cummulative.

The NAUI ND Tables allow for a BT of 55 minutes at 60 FSW. If I decend and ascend three times within this dive (at 30 FPM) and the BT is less than 55 minutes, I am diving in complyance with the tables and will complete Dive 1 as a no decompression dive. No rules have been broken and no "bad example" is being shown. So what is your complaint????

Teaching basic students "one ascent, one dive" is not based on how the tables are to be used, rather a reflection of an individual's teaching style. If anyone is "stretching the rules to fit your teaching style" it's you. It's becoming more clear why you advocate the use of diving computers...

 

[Thalassamania]

So would I. I suppose you have one that states that a 60 fpm ascent from 25 feet is a good idea, right? I actually teach that the final ascent should be less than 10 fpm. I wonder why all the agencies changed from 60 fpm to 30 fpm??? They should have asked you first, huh? Here's all DAN has to say about ascent rates: Divers Alert Network They say that "Most Experts" say that the ascent rate has an affect but we really don't have enough data. You should notify them that you disagree with this assessment and that all ascents from your safety stops should be at 60 fpm. After all, that's what you are teaching by example.

Ascent rate is a value that you plug into your model when you cut a set of tables, not a constraint, but rather an endpoint at the extremes, for reasons other than decompression considerations.

So would I. Recurring ear problems are the most common that I have heard of. My NAUI CD, Wayne Mitchell told us that he had injured himself more than once doing multiple CESAs. He blamed his increasingly bad hearing to those injuries but old age certainly was a factor.

I am amazed that Wayne, whom I knew for many years, had not learned how easy it is to avoid such problems by gently pressurizing your pharynx prior to descent.

But at least you admit that injuries occur during CESAs. Why expose ourselves to such nonsense?

Expose ourselves to our inability to properly clear our ears? Now that's nonsense, I just learned how to clear my ears ... problem solved.

Can you provide a study showing that the risk of doing all these CESAs have saved even one life? Or, even better, that doing only horizontal CESAs has cost a life?

Nonsense again, what risk? You say the problem is ear clearing, I say you're looking for a regulatory solution to a skill problem.

I said at the very beginning that the information that I had was anecdotal. I am not sure why everyone is asking me for something I never said I had? I was asked just this past spring to do a series of CESAs for an instructor out of Miami. Not could I not do them for him, as I was not an instructor for his agency, but I told him I would not do them for him. All of the instructors I refer to are from Florida. While I meet more than my fair share of instructors doing what I do, I really found it quite alarming. Consequently, I have shared that here. Accept it or reject at yours and other's peril. As for me, I'm not going to subject this 55 yo overweight body to the rigors of multiple quick ascents from any depth. Your perceived level of acceptable risk in this case may be quite different than me. I'm way OK with that. I don't possess the arrogance to believe that I can dive like Aquaman and get away with it all the time.

I did not realize that I and everyone I've ever trained all have the ears of a Super Hero, that's exciting!

 

[The Chairman]

DCBC, please research bubble pumping. You're missing the real risk of multiple ascents. I would say doing the three dives in such a manner to be excessive and not something the tables were designed to compensate for. Yes, I would call that a bad example. You left off the 10fpm at the end of every dive. Do you require your CESA students to honor that part of your protocol?

Thall, not everyone's physiology is the same and it's not just ears we are exposing to trauma/risk. While DCBC has been trying to justify his multiple ascents/descents with tables, I have not. There are a plethora of risks associated with multiple and rapid ascents, tables notwithstanding.

As for your comment about having the ears of a super hero... do you really need to taunt? This has been a great discussion so far and I hate to see it descend into a stealth flame fest.

 

[Thalassamania]

You introduced Super Heros, not me: "Your perceived level of acceptable risk in this case may be quite different than me. I'm way OK with that. I don't possess the arrogance to believe that I can dive like Aquaman and get away with it all the time." The clear implication being that I do posses such arrogance. I was just letting you know that it is only my Eustachian Tubes that, in fact, posses such arrogance.

As far as bubble pumping is concerned: It is my understanding that bubble pumping requires a diver with sufficient dissolved nitrogen to bubble on ascent on the venous (low pressure) side. This is not going to happen without a fairly significant dive, and is not going to happen with a dive to 20 feet (of so) regardless of duration. Further, it requires a descent, after such bubbling, to a depth such that the ambient pressure is sufficiently increased so as to compress the bubbles to a size that permits them to travel through the capillary bed into the arterial circulation, followed quickly by an ascent back to the surface so that the bubble may reform in a troublesome location. A descent to even 33 feet will result in a bubble radius compression of less than 25%. I do not believe that a small number of CESA yo-yos, followed by a decent to 60 feet or so at the end of the the CESAs for at least 10 minutes or so, will present any issue for a diver.