computer useage in DIR ? ?

[BigJetDriver]

MikeFerrara once bubbled...


Could you define accurate in the context of decompression?

As a pilot you use weather reports. They take accurate measurements all over the world and using sophisticated methods generate predictions that are often wrong.

Actually, they (the point-source reports and predictions that we use for the landing fields) are generally NOT wrong, and if they err, the result is that the weather is usually BETTER than predicted. Also, if you have ever flown the North Atlantic in winter, you know that there are times when you'd practically be willing to sell your first-born to continue getting the real-time IR satellite shots to tell you where the weather actually is located!

Now as for checking the Weather Channel to find if one should take an umbrella to work...well...we all still use many grains of salt there!

As for defining the word "accuracy" in terms of decompression, that argument falls more into the realm of high-level mathematics than anything else. One of the best sources we have today is Dr. Bruce Wienke of the Los Alamos National Laboratory. He is a very personable and pleasant fellow, and quite willing to talk about his work in layman's terms. Because he is a diver, his work is well grounded in reality. His latest book, TECHNICAL DIVING IN DEPTH, goes into that subject at length. The math is included as proof of concept for those who understand it. For those who are not so mathematically oriented, there is enough verbiage to make his points clear in plain language.

 

[Braunbehrens]

Diver0001 once bubbled...
And when I asked him Braunbehrens said some things with the waving hand that I couldn't follow because it wasn't detailed enough and then started talking about walking in the forest and drinking water. He says the knowledge is too dangerous for people like me (ie. strokes) and I haven't been able to get my middle finger back down since. I'm still feeling insulted. :whack:

I'm really sorry if I've somehow offended you, that was not my intention. I don't think you're a stroke, and I don't like to use that word.

I would be happy to answer any question to the best of my ability, short of giving you the rules I use for deco.

 

[jonnythan]

Braunbehrens once bubbled...


I'm really sorry if I've somehow offended you, that was not my intention. I don't think you're a stroke, and I don't like to use that word.

I would be happy to answer any question to the best of my ability, short of giving you the rules I use for deco.

It sounds like the methods you're describing come from a good understanding of and experience with decompression dives.

Is this the case, and do they teach that method in DIRF?

 

[Braunbehrens]

I don't know what they teach these days in DIR-F classes, I took mine in the early days. It probably somewhat depends on the makeup of the class.

I don't know how good my understanding of deco theory is...but there are a few things I've learned, and I use them in a common sense approach, along with some simple rules and some tables for a general reference.

When you do similar dives a lot you end up having a good idea of what is required. This is a huge advantage over using computers.

 

[Braunbehrens]

Deco is not an "exact" science. Otherwise no one would get bent following the the rules, but there are plenty of 'undeserved' hits.

It's a matter of understanding the right shape, doing the deep stops, etc. This applies to EVERY dive.

 

[Diver0001]

Braunbehrens once bubbled...


I'm really sorry if I've somehow offended you, that was not my intention. I don't think you're a stroke, and I don't like to use that word.

I would be happy to answer any question to the best of my ability, short of giving you the rules I use for deco.

Ok. I can't very well stay mad at you forever.

To start with I'm not after your deco rules. I'm not about to run off and apply the magic formulas and I'm neither reckless nor stupid enough to start experimenting with this kind of thing on my own.

However

I do want to know how the machine works. It's partly curiosity and partly so I can get a feeling if it's useful enough to consider taking a course. What I'm after is a big picture in enough detail that I can see how it all hangs together and so I can get an impression of it's utility in real diving.

I'm not quite sure where to start but lets start with your point that you need a different way to think about deco. Do you mean we need to forget Haldane?

As far as the tables go I'd like to know what kinds of informatoin are on the tables and why. For example, is it a list of M-values and 1/2 times at some kind of baseline pressure? That's the only thing I can imagine it being but I must be missing something because you'll need to have some kind of indicator of which compartment is leading.

This is the level of information I'm after. Let's just leave it at that for the moment so I can see if I'm going in anywhere near the right direction to start with.

R..

 

[jonnythan]

Braunbehrens once bubbled...
I don't know what they teach these days in DIR-F classes, I took mine in the early days. It probably somewhat depends on the makeup of the class.

I don't know how good my understanding of deco theory is...but there are a few things I've learned, and I use them in a common sense approach, along with some simple rules and some tables for a general reference.

When you do similar dives a lot you end up having a good idea of what is required. This is a huge advantage over using computers.

How do you do *any* dives outside the scope of a basic table without a computer?

 

[MikeFerrara]

BigJetDriver69 once bubbled...


Actually, they (the point-source reports and predictions that we use for the landing fields) are generally NOT wrong, and if they err, the result is that the weather is usually BETTER than predicted. Also, if you have ever flown the North Atlantic in winter, you know that there are times when you'd practically be willing to sell your first-born to continue getting the real-time IR satellite shots to tell you where the weather actually is located!

Now as for checking the Weather Channel to find if one should take an umbrella to work...well...we all still use many grains of salt there!

As for defining the word "accuracy" in terms of decompression, that argument falls more into the realm of high-level mathematics than anything else. One of the best sources we have today is Dr. Bruce Wienke of the Los Alamos National Laboratory. He is a very personable and pleasant fellow, and quite willing to talk about his work in layman's terms. Because he is a diver, his work is well grounded in reality. His latest book, TECHNICAL DIVING IN DEPTH, goes into that subject at length. The math is included as proof of concept for those who understand it. For those who are not so mathematically oriented, there is enough verbiage to make his points clear in plain language.

Actually Bruce Wienke is a member of this board. We all know who he is. I have and have sifted through most of his book TECHNICAL DIVING IN DEPTH. However most of the good work he has done has been totally ignored by the folks who programmed your computer. Some of us however conduct out decompression in a mannor (or shape) that will resemble an RGBM profile far closer than what your VR3 will provide. Since your computer uses no "AI" and has no idea about how YOU felt after your last dive it is not able to learn as you can. The computer just spits out numbers based on calculations using measurements of depth, time and the buhlmann model. I personally know folks who have gotten very bent while their computer was very happy. While the measurements may be accurate and the calculations complex they still don't seem to accurately predict the outcome. I saw their profiles and I would do the same dive very differently and the computer would be of non help at all. I know how deep I am and how long I'm there. If I choose I can use max depth to calculate decompression or I can use the knowlege that I actually had a multilevel profile to modify it. I can also take advantage of past experience and better deco shapes using gradient factors (or whatever).

Now, I don't tell any one that they shouldn't use a computer. I never refer to myself as DIR and I'm not GUE trained but I have done some diving and know what lever of confidence I have (or don't have) in the gamoke who programmed the computer. I also know what I did on dives wher I didn't feel so good afterwards and what I did on dives that I felt great after. If you can find a computer that knows that stuff I'll pay double for it.

Then there are the advantages you find in simplifying dive planning by knowing ahead of time what your deco will look like. As far as I'm concerned a little extra deco isn't the danger it's the wrong deco.

Who knows maybe some day some one who understands diving will build a computer and I'll give it a try. In the mean time though I'll buy a lot of gas with the money that a multi gas trimix computer costs. I will also end each dive knowing that my ascent schedule worked well the last time I used it rather than hoping the computer spits out a surprise schedule that works.

 

[ERP]

OK I'm going to try and come at this from a different angle, I'm not DIR trained although the majority of my dives have been with a DIR trained buddy, and I do intend to take DIRF shortly.

Being the inquisitive sort I tend to ask a lot of questions and discuss things like the merits of a computers (and yes I dive one in computer mode).

It seems to me that the Computer/Non-computer proponents in this thread are arguing about different things, and I think that some of the message is getting lost.

It is my understanding reading this thread that the No-Computer proponents are trying to convey, is not that computers in and of themselves are bad, but rather that they don't tell the whole story, and reliance on a computer is a bad thing for this reason alone.

A computer doesn't control your profile, you do. A bad profile is a bad profile whether the computer says your inside the NDL or not.

All dives are deco dives, the only real difference is where you do the deco, in the water or out of it at 1ATA. With the right profile, you can feel much better after a dive.

DIR trained divers do not use computers, because even with rec like profiles the computers do not allow them to dive the profiles they find most effective without complaining (insisting on a 3 minute safety stop). And obviously on dives with planned deco, computers are not useful, because of gas switching and the algorythms in use.

If I'm misreading here, I'm sure someone will correct me.

 

[Charlie99]

Braunbehrens once bubbled...
I would be happy to answer any question to the best of my ability, short of giving you the rules I use for deco.

Hmmm. Makes it difficult to compares different options.

This leaves the two options that are publically discussed on this board being:
1. Use tables
2. Use computers.

Once someone has low enough SAC that the tables become the limiting factor, computers are an attractive option.

It would be nice to discuss other options, but clearly that discussion will not be with you.

Charlie