Why do computers rot the brain?

[madmole]

Some of us had 1000 or so dives under our belt before computers were even invented, so we know how both table and computers work and guess what Computers and tables are the same thing, there aint no difference in the algorythm. RGBM tables are the sane as an RGBM computer, I bought my first computer in 84 (DecoBrain) and have done another 1800 dives with them since. Not had a clinical bend yet, so I guess both work fine

Only difference is that the tables assume only one model slice to cover the whole dive, whereas the computers slice the into little 10 or 20 second chunks in their model. Do a square profile dive on a Buhlmann computer and you should get exactly the same decompression as Buhlmann tables.

So neither are better or worse. You hit the nail on the head when you said it was the diver that makes the difference (and how they were trained). Some divers shouldn't be allowed near the water with computers or tables, but at least with a computer, there is a third party in the water with them to beep at them when they are about to do something stupid.

You can screw up both dives if it goes wrong and you can get bent on either method. The computer is just more flexible in real use on real dives which are not very often square profile.

Some agencies teach deco from day one, others will give you ticket to dive without every explaining it to you, until you come back for the advanced class :upset:

Personally I plan my dives in advance (So I have a feel for times and depths etc) and carry tables for worse case scenarios. I do however do the dive following my computer (and its backup) as I can then swap PPO2 setpoints, swim up and down the wreck etc without getting penalised. If I swap back to tables I have to assume lowest PPO2 and deepest depth for the whole dive and do a ton more deco.

I can use a slide rule or log tables to do maths (I'm so old I was taught those at school), but I'd much prefer a calculator

 

[Uncle Pug]

AquaTec once bubbled...
it concerns me that you guys have such a difficult time finding this point

here is an example of my line
100 feet for 20 minutes allows me a direct ascent to the surface
100 feet for 30 minutes requires a deco stop prior to surfacing

Doug you might want to ask Dr. Deco about this in his forum.

 

[boomx5]

AquaTec once bubbled...
100 feet for 20 minutes allows me a direct ascent to the surface

Would you really do that?

 

[AquaTec]

Uncle Pug once bubbled...

Doug you might want to ask Dr. Deco about this in his forum.

this thread is why computers rot your brain..

it went from computers to tables....then some of you said you don't even use tables.....

you do a minimum deco profile...30...20...10 etc.

then it was discussed that if a deco profile was required it was not recreational......

it has also been discussed and agreed that you are nitrogen loading as soon as your face hits the water, but there is a line when it can be off gassed durring a direct ascent, and when a stop is "REQUIRED"

this brings me to this question..which is appropriate in this thread....when does a deco profile go from recomended to required based on your principles of dive planning

meaning no computer or tables

 

[AquaTec]

boomx5 once bubbled...


Would you really do that?

A 100 for 20 is within the NDL and yes i would do this dive

 

[Uncle Pug]

AquaTec once bubbled...
this brings me to this question..which is appropriate in this thread....when does a deco profile go from recomended to required based on your principles of dive planning

meaning no computer or tables

You misunderstood me.... I am not trying to blow you off or say that you shouldn't ask that question here.... just thought you might want to quiz Dr. Deco on the notion of a *line* between deco and no deco required.

So to answer your question here... there is no line between deco and no deco required.

We do a minimum deco of 1 minute at 30,20,10 on all dives and call it that. We don't pretend that there is a line... there isn't. We face the fact that as bottom time/depth increases the number and times of required stops will increase. We also understand that the penalty for omitting required deco becomes more certain and excessive as the dives grow in duration and depth.

When I have used the term NDL it is not to imply that such a line or limit actually exists... I am merely referencing the limit that has been set by most training agencies (though they all seem to have "their" line drawn in different places.

Again, you might want to check with Dr. Deco for a better explaination.

 

[AquaTec]

I undertand the line ..or lack of pretty good.

Now i understand your phylosiphy a bit better....

let me see if i have this right.


any and all dives you believe that you should do a deco stop at a minimum of 30/1, 20/1, 10/1

from a decompression theory this makes all the since in the world, and from the training DIR provides..focussing on boyancy control...then it makes since.

except for one thing, and i guess this comes from my years PADI

A recreation diver should not dive in an over head enviroment. it seems that your system is an overhead enviroment.


Well saying that GUE doesn't teach an entry level diver, so it is the next step, therefore i don't have a problem with this principle, as long as the bigginer or occasional diver can always have direct ascess to the surface..i guess that s really my point.

after that nothing wrong with teaching deco procedures...

 

[Uncle Pug]

AquaTec once bubbled...
except for one thing, and i guess this comes from my years PADI

A recreation diver should not dive in an over head enviroment. it seems that your system is an overhead enviroment.

Recognizing the truth about the NDL does not create an overhead environment.

 

[AquaTec]

true but being required to perform deco does

 

[Uncle Pug]

AquaTec once bubbled...
true but being required to perform deco does

Even PADI recommends the 15 foot "saftey stop" and it is almost identical in effect to the 30,20,10 (other than lacking effective slowing of ascent from 30 to the surface.)

The saftey stop doesn't create an overhead nor is it required if for some reason the divers must surface. But it is becoming more and more a *rule* and even dive computers are demanding it if certain parameters have been exceeded (ascent rate for example.)

The same holds true for what we call minimum deco of 30,20,10 but we are just being forthright about what it really is... recognizing the truth that all dives are deco dives and that to be safe, stops should be made to allow the body a chance to offgas.

The difference between the two philosophies is this:

One says, "There is a line (the NDL) and if you do not cross that line then you can omit the safety stop with impunity."

The other says, "There is no such line only an increasing inert gas load that must be dealt with to avoid problems... and you need to be aware that if you omit a portion of your deco you may face consequences... and the more deco you omit the greater the chance of that happening and the greater the consequences."

In practice if we need to omit a portion of the minimum deco we would... the point is we are looking at things as they really are so we can make informed decisions.

How safe is it for some AOW diver to go out and do a dive to 100' for 20 minutes thinking all the while, "Well I know I'm supposed to do a 15' stop for 3 minutes but as long as I don't cross the NDL I can go ahead an skip it." Maybe they can and maybe they can't.... but thinking that way could get them into trouble.

Maybe the thought crosses their mind as they go for that one last fish knowing that they will not have enough air to do the safety stop but thinking, "It really won't matter, it's just a safety stop."

Or maybe having gotten that fish, run low on air and having crossed the *line* they think, "Oh No!!! Now I am into decompression and I must make my stop!!!" and they try but they run out of air at the stop.