NDL

[The Chairman]

To me, the amount of gas I have is more important that the amount of NDL time I have.

It ain't the tables...

It ain't even the steenking (com)puter...

It ain't your Dive Master...

An sho enuf, it ain't your Dive Instructor...

It IS the diver and the whether he uses the grey matter betwixt his ears.

Tables don't make you smart....

(Com)puters don't make you stupid...

Dive Masters and Instructors can only teach what you are willing to learn and apply.

NONE of these will enforce modest bottom times, slow ascent speeds and/or doing your safety stop. That, my dear diver, is YOUR CALL!!!

 

[Dr Deco]

Dear Readers:

Long Thread

This is one of the longest threads on SCUBA BOARD, and I appear to have missed it. It looks as though virtually all of it occurred on one day (May 15th); if I was busy that day, the shooting was over.

Decompression Theory - An Editorial

I would like to comment on decompression theory and the various opinions that are bandied about. This is an actual example of science at the working level. In school, students learn that scientists propose experiments, test their theories, and decide on the truth. This is not exactly true for science “in the trenches.” There is a considerable amount of personal opinion, distrust, fighting over scarce research dollars, etc – just like everything else in the world. Scientists are ordinary people with ordinary faults. They can have an “agenda” just as anybody else.=-)

Because scientists must compete for research money, they often will have a desire to see their opinions adopted by government (or private) agencies. Likewise, they obviously are believers in their ideas or they would not be pursuing them in the laboratory. Scientists will push their work. In short, nothing is absolutely pure. This means that “contemporary theory” will often depend on whom you ask.

My Bias

I try to give what I believe to be the “real skinny” as I see it. This is tempered by several decades spent as a research scientist. These experiences are not the same as those shared by other researches and this will color their views. I have not seen all that they have and vice versa. Dr D tries to give a complete answer but sometimes it is one man's opinion. You will not necessarily receive the same answers from DAN or Drs Brubakk, Vann, Wienke, or Powell (to name but a few).

Deco Meters

Another thread has been discussing the DCS situation with a meter that was reported to have a program defect. A lawsuit has arisen from the injury. I see two aspects to the general situation.

Divers believe very strongly in the veracity of these devices. Despite the fact that my SCUBA BOARD replies indicate that microbubbles generated by physical stress are not incorporated into the algorithms, divers trust these devices to the hilt. This is bad science and practice. Divers control the dive and gas loads.

Purveyors of deco meters, on the other hand, will make claims that their meters have a such and such algorithm and give the impression that all has been accounted for. This is bad science and practice. Divers control the dive and gas loads.

Dr Deco :doctor:

Please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[The Chairman]

But won't these failings also apply to table diving as well? Sure, you could move over a letter group, but in all reality will the average diver do that? And do they know when to do that? Will increasing the conservatism on your computer accomplish the same thing?

I guess I am wondering if you feel that diving tables is inherently safer in some way... thanks in advance!

 

[The Chairman]

when are you having a deco class over in Florida?

 

[Dr Deco]

Dear NetDoc:

Tables versus Computers

Yes, the same failings of computers apply also to tables. You can push tables and you can exercise excessively with tables. The “problem” with computers is that, if you go to the max NDL, you are always at the edge of the model. This should be sufficient and the tables are tested under these limiting conditions. However, divers sometimes exceed the test conditions. :boom:

Problem

The problem is what I read here on SCUBA BOARD. The vast majority of divers rely totally on computers. This is simply a derivative of the “computer age.” I have seen in scientific papers something to the effect “The data was analyzed with a XXX computer program.” While not done as much today, this gave the impression that the computer did a better analysis than a scientist with a paper and pencil did. The data will decide the result, not the analytical tool.

Computers are wonderful, but they do not analyze situations.

Dr Deco :doctor:

Please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[gkwaldee]

UP,

The only machine that generates O2 from water is the O2 generator we have in the machinery room on the Submarine I am attached to. And its too big and dangerous to carry underwater, something about the hydrogen it stores........but thats another story entirely, and is beyond the scope of this forum.

I guess "puter" could have been misleading to a golfer, but since I was in a diving forum, speaking on diving COMputers, and I purposely felt out the extra "T" that is needed to properly spell putter............I just assumed I would be understood...........I know what we get when we "assume" and I must say that, in this instance, Im to blame for the fopah. Not to mention that the word belies a lifestyle that may be considered "geeky" vice the cool persona of a diver. Again, my bad.

The phrase "Tiny bubbles" refers to those little bubbles that we all blow when we dont have a regulator in our mouths.........in other words, dont forget to move air when underwater. OR maybe Im a Don Ho fan and just cant get that song outta my head...........who knows? Ill ask my shrink the next time I see him

Anyway, I wasnt offended by your comments, but it has enlightened me as to the state of mind some here are in..........I must remember that getting Narced has lasting effects on the mind..........maybe is the N2 and NOT the COMputer that rots the brain..............food for thought there.

dont forget to move.............fu@# that!........

tiny bubbles hehe

 

[gkwaldee]

I would hope that anyone taking on the sport of diving would understand the basic concept behind the effects of pressure as it relates to a given gas. If they dont, they certainly are playing a game they are ill-equiped to win.

Volume and pressure.................hmmmmmmm, must be what they were talking about in Submarine school as they taught us about the Ho-Ho-Ho accent.....of course, now its the good ole "ahhhhhhhhhhhhhh". Same difference, except that N2 will expand in various places, while they were mainly interested in ensuring that air didnt expand in the lungs and ......well

The bottom line is whether or not one is willing to push the "limits" for the sake of enjoyment when the price for such action is so high. I have posted before that we are not such people, there is just too much to enjoy in life, and this is just a sport..........I push the limit by being places that I shouldnt be, doing things that other people wouldnt like if they knew I was doing it...........but thats my job

As for pewter............its an alloy, while "puter" is geekese for computer.......

Geesh, this is a tough board.........id better fire up, i mean "use", the spell check before i hit "send"

anyway,
tiny bubbles