computer useage in DIR ? ?

[Braunbehrens]

Erp, you are right on.

Diver0001, I just have a set of basic tables with only the long stops.

Deco is much much simpler than most people think it is. Just a few basic rules, get the shape and the general deco time right...the rest is propellerhead BS.

It's interesting to talk about all the compartments and how they are loading etc, etc, but the fact is that this knowledge is not enough to keep anyone from getting bent 100% of the time, so it's really only useful in terms of understanding what the general curve is supposed to look like. It's also insufficient at explaining why some people DON't get bent doing some really really stupid stuff.

All that fancy math is like trying to figure out the 8th decimal point of a distance that was arrived at by eyeballing an area the size of a football field.

As Mike says, take the deco program and play with it. For the same dive you can get wide changes in deco time, stops, etc etc. just by changing a few of the parameters. What does this mean? It means that you should find some values that work for you, adjust the shape so it is the right shape, take a few other simple rules into account, and go diving. Start with some conservative values, and go from there.

I know that people don't like George Irvine because he can be a bit harsh at times. However, he's posted a lot of good info about deco.

Again, I'm no expert, and I don't think you need to be one to figure this stuff out. Just play with this stuff, spend some time with it, try a few dives, see how you feel, don't push things until you are more comfortable...

I'm not all that happy posting even this much. I AM NOT AN AUTHORITY ON THIS! Do it at your own risk, and verify antything you hear from some yahoo on the internet (me) by more serious means (such as taking a class).

 

[Charlie99]

Braunbehrens once bubbled...
I know that people don't like George Irvine because he can be a bit harsh at times. However, he's posted a lot of good info about deco.

He has postedc some interesting stuff on repetitive dives:
... http://www.wkpp.org/articles/Decompression/repetitive_dives.htm

 

[BigJetDriver]

MikeFerrara once bubbled...


However most of the good work he has done has been totally ignored by the folks who programmed your computer.

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.....

____________________________________________________

Mike Ferrara,

I do know how I feel at the end of the dive, and most of the advanced computers on the market will let me reset the physiological and conservatism factors as I need to!

I have to believe that you did not read my original message. In it I did state that the VR3 does NOT utilize the RGB model. I sure would like to persuade Kevin to let the end user install that model if so desired. (if anyone has any influence in that sphere, I definitely would like their help.)

As for my original contention, I know of no one who is faster than a speeding microchip at these kinds of calculations. (If you are, I do suggest you apply at Professor Xavier's school. I will, however, wait for verification by people like Sawatzky, Wienke, and Vann before I believe it.)

And since you have, by your own account, read some of the literature, you know full well that on any given day YOU can be bent by what YOU do, just as easily as any other diver within any other "safe" profile.

 

[Diver0001]

Braunbehrens once bubbled...
Erp, you are right on.

Diver0001, I just have a set of basic tables with only the long stops.

<snip>

You mean something like the navy deco tables? If that's your starting point then the rest would be to work out proper ascent rates, deep stops and your profile to get a deco procedure that works for you. Am I pointed the right way now?

How do you plan your gas? You'd need to have at least some idea of your profile before you start even if we assumed that your deco stations were surface supported (which is probably very un-DIR like). The reason I'm asking this question is because something you said a few posts ago made me think that you just go diving and work out your deco on the fly at your first stop. You could obviously do it with tables if you know where your first (deep) stop will be but there must be more to your planning than just jumping in.....

R..

 

[Richeod]

I don't have the time to get into a back and forth on this board but there are some things that need to be cleared up.

1st.

DIRF is NOT a deco class. Its purpose is to teach basic skills, dive planning, and the reasons why specific equiptment is used. On the fly deco is NOT taught. GUE does have a set of minumum deco tables (NDL's if you will). There use is covered. They teach things differently, i.e. averaging depth and an alternate way to plan repetitive dive times. They also do a series of 1 minute safety stops rather than the 3 at 15. The tables are designed to be easy to use rather than getting every last minute of bottom time. If after the class you want to use a computer for diving so be it. DIRF does not turn you into a DIR diver nor does it prepare you to join the WKPP. It just gives you the building blocks to enable you to continue further if you so desire.

2nd.

Tech 1 is where deco theory is introduced. Again GUE does things differently here. The tables that Paul caries are a set of ranged air tables cut with decoplanner. The GF's are set (to a standard setting) and away you go. The tables (about 3 pages in your wet notes) are carried and modified (in your head) depending on backgas used and deco gas used. It is very simple and easy to use. And that is as detailed as I am willing to get. Sorry, take a class.
On the fly deco is done differently, and also introduced in Tech 1. It is just that, ON THE FLY. You do it all in your head while you are diving. It is so easy as to be laughable, and it works VERY well. I have never felt better after a dive.
You DON"T just jump in the water without planning the dive though. You figure out how much you can do on the surface (based on gas) and use that as a maximum. Then you plan what you want to do.

Hope that clears up some of the confusion.

 

[Braunbehrens]

Since the cat is out of the bag, re. depth averaging, I'd just like to shove it back in ;-)

Well, no, but please don't just "average" your depth. That does not work! You have to get a feel for it, weigh things a certain way, be aware of your depth at all times, etc.

PLEASE don't use this stuff without taking a class or at least diving with someone who does it and having them show you. This is not something you pick up by reading a post on scubaboard.

P.S. It took some time, but all my minimum deco times, and deco tables fit on 2 pages, I even have room for a couple of other tables, such as a cheat sheet that helps when you have divers with different sized tanks.

And he's right when he says that it's so simple it's laughable.

Remember, deco is a large approximation, not an exact formula. Figuring things out to the minute is not going to help. It may make you feel better in your head, but it won't affect the likelyhood of you getting bent. If you want to reduce that likelyhood, add a few minutes to your deco.

 

[BigJetDriver]

Braunbehrens once bubbled...
Remember, deco is a large approximation, not an exact formula. Figuring things out to the minute is not going to help. It may make you feel better in your head, but it won't affect the likelyhood of you getting bent. If you want to reduce that likelyhood, add a few minutes to your deco.

Help me to understand something here, please. Are you saying that the way to avoid getting bent is to estimate or take a "wag" at it, and just sprinkle in a few extra minutes to your deco?

 

[Uncle Pug]

BigJetDriver69 once bubbled...
Are you saying ... a "wag" at it

That isn't what he said.... and it certainly isn't what he meant.

 

[Braunbehrens]

Thank you Uncle Pug.

No, I'm saying that the way to avoid getting bent is to understand how deco works, and what works. Not by using some fancy gizmo.

The numbers in question are all crude approximations. However, the SHAPE of the deco and a few other things, are far more important.

For example, you mentioned (correct me if I'm wrong) that you drive some kind of rig that keeps you at a constant PO2. This is exactly what you don't want, if you understand deco. Rather than having your PO2 high on the bottom, where the risk and danger of tox is much higher, keep it low and offset some of that oxygen with helium, which is easier to deco from. Once you are shallow and doing deco, go for the maximum gradient by using a PO2 of 1.6, but don't stay on it. Take frequent low PO2 breaks. The reason for this is that your ability to offgas actually decreases when breathing high PO2's for lengthy time periods. Low po2 breaks will prevent this and your deco will actually be more effective.

Another reason to avoid high po2's on the bottom is that you only have so much "high po2 reserve". If things turn out really bad, and you need to hit the chamber, you'll be in deep trouble if you've exhausted this reserve! The treatment will be ineffective, and possibly dangerous.

I shouldn't even be saying all this, I'm not really the right guy to listen to on this subject. There are people who know a lot more, and understand this a lot better. Much has been written about it. I suggest you take a look at it. DO NOT DIVE BASED ON WHAT I SAY! DO YOUR OWN RESEARCH! Better yet, take a class. Sorry for the all caps, trying to keep it clear.

 

[Divesherpa]

Hey Paul,

What would be a big dive for you? I'm only referring to bottom times, depth, and total time in water.

Cheers and safe diving,
Jamie