Is UTD still a "fringe" organization?

[tursiops]

This gave birth to the notion that we are all bent after every single dive

This is silly. Are you bent if there are no symptoms? Once again, you are confusing bubbles with DCS.

 

[CAPTAIN SINBAD]

This is silly. Are you bent if there are no symptoms? Once again, you are confusing bubbles with DCS.

Goodness, did you even read my whole post? As I explained, prior to Doppler this term at the scientific level would imply the existence of bubbles and is used as such in early documents. If you were not bent then you cant have bubbles. It is not me, this is what was believed. Doppler research showed that to be wrong and if that meaning is carried today then we are all bent whether we have symptoms or not. Modern discussion is better served by silent bubbles and symptomatic bubbles.

 

[tursiops]

Goodness, did you even read my whole post? As I explained, prior to Doppler this term at the scientific level would imply the existence of bubbles and is used as such in early documents. If you were not bent then you cant have bubbles. It is not me, this is what was believed. Doppler research showed that to be wrong and if that meaning is carried today then we are all bent whether we have symptoms or not. Modern discussion is better served by silent bubbles and symptomatic bubbles.

What is the point of the history lesson and the extensive quotes from Powell? We know the history. We've read Powell. What critical thinking are you applying to all this, or is the point just to wear us out?

 

[Ulfhedinn]

Raises Hand... That would be me... Yep didn't like it all once I "really" put it to work but the check was already cashed. Just want to get back half and I would be happy.

Right, whilst we're here talking about UTD, someone's just posted about a UTD "Z" sidemount system. What on earth is that all about???

Sidemount's about as simple and reliable as you'd ever want. Sure, it's a bit fiddly to get configured to your exact sizing, but once over that, it's superb. I just don't understand why anyone would want to complicate it by adding a manifold. Sidemount's pretty much standardised to a short hose to bungeed necklace on the LH cylinder and a longhose around the neck to the RH cylinder. The only modification from "DIR" would be the use of a break-away O-ring to secure the longhose boltsnap -- so you can pull it off your RH D-ring when breathing from the other reg.

Anyone know why they add a manifold and another valve behind your head, when the two cylinders are perfectly happy beside and in front of you -- it's a hell of a lot more accessible than getting to the valves of backmounted cylinders!

 

[Ulfhedinn]

Ha ha.

And now for some SB Trivia: TSandM (Lynne Flaherty) said it was she who coined the name "Unified Team Diving."

I suspect Solo Team Diving was rejected for several reasons.

That's a name I haven't heard in a while... sure do miss her.

 

[ginti]

Sorry ginti. I didn't mean to ignore. I had my first vaccination shot and it is knocking me out so I had intended to respond when I was a little better. Hopefully, the following will address a lot of confusion that some of this earlier conversation has created.

Well, thanks for your answer, I am sure it took you time, and I really appreciate it I believe most of us have read and appreciated the book from Powell, but it's always nice to see a recap. Just keep in mind that "Dr. Simon Mitchell" is a mind in the field, together with all other researchers. Mark Powell, present UTD leadership and all other dive industry representatives - well, they are absolutely not minds in the field.

Regarding my previous questions:
1 - what do you mean by "being bent"?
I am a bit confused now. You know that having bubbles is different from having symptoms, and you know that everyone always has bubbles in the body. But you referred to the old concept that every diver is bent. Also, previously you associated being tired with DCS (being tired and having DCS are two different things). So it is still not clear to me what is your concept of "DCS"/"being bent"... I think that if you state it clearly, you will solve a lot of misunderstanding in this post.

2 - can you link the article you cited?
I refer to the article where the authors said that "a significant" number of recreational divers get bent within NDL. This is very surprising for me since I have always found that recreational scuba diving is incredibly safe (but never on a scientific paper). I still cannot find this article.

3 - what did you mean when you said "significant" in your previous post?
This is still not clear to me; "significant" is a vague word: maybe something is significant for you but not significant for me. By the way, in that paper, authors surely quantify their findings.

If the vaccine still has some side effects on you and you cannot answer - well, now I understand what's happening.

Many thanks!

 

[boulderjohn]

2 - can you link the article you cited?
I refer to the article where the authors said that "a significant" number of recreational divers get bent within NDL. This is very surprising for me since I have always found that recreational scuba diving is incredibly safe (but never on a scientific paper). I still cannot find this article.

I have been thoroughly confused by his statements here from the beginning. I think he is confusing the concepts of "significant number" and "significant percentage." I got the idea he went to a UTD workshop where he was shocked to learn that a significant percentage of people who get DCS were within NDLs and thought that was roughly the same as saying a significant number of people get DCS while diving within NDLs. I also got the impression that the UTD presenter was intentionally creating this misunderstanding.

One of my earliest and most futile posts in this thread tried to explain the difference between percentages and total numbers. One of the most common estimates given for the percentage of dives leading to DCS is 0.02%. Let's convert that percentage into a number. It means that for every 10,000 dives completed, a grand total of 2 dives results in DCS. That is a very small number. Let's say it turned out that 75% of those 2 dives were diving within NDLs. That is a very large percentage, but the actual number (1.5) is very small.

As I also said, the overwhelming majority of divers dive within traditional limits, so you would expect that percentage to be high--but it is still a very small number.

As I see it, Captain Sinbad is trying to claim that a large percentage of an extremely tiny number is the same as a very large number, and he is claiming that this means the traditional limits are not effective when in fact the statistics indicate that they are very effective indeed.

 

[ginti]

...

I have the same impression of you actually, this is why I would like to read the original scientific article...

 

[tursiops]

I have been thoroughly confused by his statements here from the beginning. I think he is confusing the concepts of "significant number" and "significant percentage." I got the idea he went to a UTD workshop where he was shocked to learn that a significant percentage of people who get DCS were within NDLs and thought that was roughly the same as saying a significant number of people get DCS while diving within NDLs. I also got the impression that the UTD presenter was intentionally creating this misunderstanding.

One of my earliest and most futile posts in this thread tried to explain the difference between percentages and total numbers. One of the most common estimates given for the percentage of dives leading to DCS is 0.02%. Let's convert that percentage into a number. It means that for every 10,000 dives completed, a grand total of 2 dives results in DCS. That is a very small number. Let's say it turned out that 75% of those 2 dives were diving within NDLs. That is a very large percentage, but the actual number (1.5) is very small.

As I also said, the overwhelming majority of divers dive within traditional limits, so you would expect that percentage to be high--but it is still a very small number.

As I see it, Captain Sinbad is trying to claim that a large percentage of an extremely tiny number is the same as a very large number, and he is claiming that this means the traditional limits are not effective when in fact the statistics indicate that they are very effective indeed.

Agreed. It is like saying that 100% of the people who got DCS were wearing swim fins.
The same fallacy was in the DAN Europe report by Cialone et al. They noted that about 74% of the recreational within-NDL divers who got DCS were using GFs of 0.7 to 0.9 (70 to 90 in the usual GF-speak). It is stated as a risk factor. But they do not state what the GFs were for the other 99.99% of the dives that did not have DCS.

 

[stretchthepenn]

Tightening: Quoting Mark Powell is not very convincing...he is a good writer and has done us all a service in make some of the less transparent material a bit more accessible... <snip>.

I agree that Powell deserves credit for helping make deco theory accessible--I just finished Deco for Divers; I enjoyed the book, and it helped my understanding tremendously--but I disagree about the quality of Powell's writing. A lot of Deco for Divers is painfully bad.