Why do computers rot the brain?

[sillygrendel]

First let me say that for being a SE and gadget person I am an incredible luddite when it comes to mathematical calculation. I don't believe people should use computers to do math while learning. It deprives them of an intuitive feeling for many odd calculations and manipulations. That being said I think they're also a great tool.

Air consumption and time... Give me a bottom timer which displays my average depth at any point in time, and an accurate SPG. With that info _anyone_ can mentally calcuate their remaining air or correspondingly the amount used or the time into the dive or... Its a trivial calculation if you know your SAC. If it doesn't display the average depth all you have to do is keep a running tally in your head. Okay -- so you have to pay attention a bit, but its not rocket science.

As has been pointed out, computers calculate your NDL based on your exact profile. In that sense they perfectly correspond to the model. Of course... They also don't leave much margin for error unless it is built into the computer . The trend has been that computers are getting more and more conservative to pad that fine line.

Planning a bare-bones square profile and diving it also has a degree of built in conservatism based on the fact your profile is really not square.

It is my guess that on dives that approach a square profile or a true 'multilevel dive', you will probably get more bottom time using a liberal table than with a conservative computer. On really wierd profiles I would guess you'd get more time with the computer. But I would guess really wierd profiles aren't all that common.

The main argument against using a computer, as I see it would be that you lose control over the degree of conservatism in your diving. Whether you feel that is a good or a bad thing depends on how much you like to push the tables... There is something to be said for being able to calculate avg depth & air on the fly and its not hard but... I don't know that it is necessary for most people either. There is something to be said for memorizing the tables but... Actually I think it would be a better idea to be familiar with the functions associated with your model of choice. In the case of perfusion based, haldane-like models, decaying exponentials are not all that difficult... For any given 'perfect' dive there will be a limiting compartment for that dive...

Wow... I have **way** too much time on my hands...

That being said I have a Vyper and enjoy it

For more serious dives it will probably turn into a bottom timer.

 

[dotyj]

Hey UP there:

What visual queues if any do you use for ascents? I don't plan to buy a computer any time soon. I've got plenty of other expensive gear to get.

I'm assuming a lot can be done with a watch and depth guage but I don't have any real world experence, yet.

I have a lot to learn.

Uncle Pug once bubbled...

It is a sad and probably irreversible state of affairs.

However I know for a fact that some can be taught to ascend correctly without a computer... (my joy is remedial education.)

 

[Scuba]

I learned to dive with a computer and found it helpful. A new diver will probably not have a good notion of his ascent rate, which a computer can point out. He probably will also not have a good notion of how much faster his nitrogen absoption is with increasing depth. When you see the nitrogen meter moving fast towards the red, you gain a better appreciation of what that 10 min. maximum bottom time means.

So I do think it is helpful and useful. Is it necessary? No. Then so are a lot of things. As I become a better diver I don't need to look at my computer as much, but I still find useful the information it provides.

Like any tool: Learn its intended purpose. Learn its capabilities. Learn how to use it. And you will learn how it may be helpul in your activities.

I heard a mention that there is a mask at the DEMA show that displays the computer's info in the mask. Top gun style. It may not be ready for prime time, but its coming. Cool. Computers are not just here to stay, but will become increasingly a fundamental piece of equipment. Just wait till they monitor your individual gas absorption in various tissues, etc. Ok, thats enough, I am getting way ahead of our time. But hopefully we will see it within our dive time.

 

[mth71]

Thanks for all the great replies! While now I'm amost more confused than ever, you sure have given me a lot to think about (and I guess that's the point to dive without a computer...so I can think ). I agree with points made by both the pro-computer folks and the no-computer guys (and gals). I certainly don't ever want to use a computer without understanding the fundamentals of the calculations involved. I'm an engineer, so I need to know the details of things before I trust doing them on a computer. But once I do understand them, I have no problem using a computer (there's no way I'm going to do a complete structural analysis of an airplane by hand!), but I also check to make sure that the answers make sense. I'm also a pilot, and I use GPS almost exclusively anymore. Does it take away calculations that I used to do by other means? Sure. Is it a "better" tool for the pilot? Absolutely!! It provides for much better situational awareness...if used correctly. I still like to check my position and progress with conventional means (VOR and an (electronic) E6-B), but flying with a GPS does allow for a safer flight as it instantly tells me if any of a given number of parameters are not what they were predicted (or forecast) to be. I suspect that the same could be said of a dive computer. However, like I said, I don't intend on getting a computer until I thoroughly understand how to carry out a dive mentally, and perhaps I won't get one even then. I have respect for what technology has done for mankind, and don't think that it necessarily rots the brain (believe me, I do so many other things that keep my mind active...I read math, engineering, and computer programming books for fun, I write software, and keep my body and mind healthy by exercising regularly). With that said, it never hurts to always back that up with wisdom, experience, and a little bit of common sense.

I really appreciate hearing all your opinions. While they might tend to overwhelm a newbie like myself, I do thorough research before coming to a final decision...that's why this board is so great!! Thanks everyone.

Mark

 

[Alban]

hello all

Just a quick mention to Mike if he really wants a Auto B.C. there is one a guy did a test on . http://www.divernet.com/equipment/0102divertests.htm#pilot

I think they have a way to go yet , but who knows what the future may bring ? it does seem like the logical step forward.

Yours Alban

 

[Dr Deco]

Dear Readers:

Computers and Decompression Physiology

Speaking only from the point of decompression physiology, computers are not really safer than tables. In fact, if you go to the limit of the meter on that particular dive, you are ALWAYS diving to the limit of the algorithm. With tables, you always “peg” to the deepest depth and next longest interval. You are virtually always WITHIN the “limit” on a table unless you do a square dive, and then you might be AT the limit.

Limits

As I have discussed on several occasions on other SCUBA SOURCE forums, “limits” are a holdover term from the old HALDANE metastable-limit hypothesis. Tissue micronuclei were introduced into decompression in the 1940s by EN Harvey, and they have been gaining favor since the 1960s. In the concept of micronuclei, there are not any table limits . Instead, there is an increasing probability of a DCS problem developing as the nitrogen load increases in the body. It is not an all-or-nothing phenomenon.

Algorithms

Surprising as it may seem, the algorithms in these computers are not available to the public. There is not any indication that they have been tested; they are repackaged US Navy tables with conservatism added. With the exception of the PADI, US Navy, and DCIEM tables, there are not any booklets available describing what is inside of them – tables or computers. The RGBM meters are a different concept for decompression diving, but not really for the simpler, no-deco diving.

Deco Physiology

For the recreational scuba diver, I have not seen anything that would indicate to me that the important physiology and biophysics has been covered to improve safety. [Decompression diving is a different story.] Many factors cannot be easily added to a deco meter. Physical activity is the major factor, after gas loading, and that is not modeled by the computer. This idea is a not the generic “exercise avoidance,” but rather is a laboratory tested fact. Activity level is inserted into every NASA decompression protocol. Some of the data is in the ATTACHMENT and shows the reduction in microbubbles after a zero, 60, and 120 minute waiting period. These nuclei were generated by physical activity (deep knee flexes.) { Dervay JP, Powell MR, Butler B, Fife CE. The effect of exercise and rest duration on the generation of venous gas bubbles at altitude. Aviat Space Environ Med 2002 Jul;30(1):22-7 }

No computer can do for you what you can do for yourself. I know that this is not “glitzy” and high-tech sounding, but it is the basic biophysics of the game.

Dr Deco :doctor:

 

[The Iceni]

MikeFerrara once bubbled...
Maybe... we need computer control bc's. That way the diver couldn't ascent to fast no matter what.

In The BSAC's mag "Dive" I read an article about a year ago where they road tested such a device.

The diver selects and controls his depth by means of the computerised console which automatically operates the dump valve and injectors for the BC according to depth. This gadget will hold the diver at the selected depth regardless of any efforts he makes himself to control this depth or rate of ascent.

Great, just programme in your deco schedule and the computer does the rest. . . .

until it fails. :boom:

I think the device did not sell well - if it was a genuine article ,and not an April fool's joke in bad taste. I believe UP's opinion on such a device would be unprintable.

In the UK most non-technical divers use (Nitrox) computers, while the technical community cut their own tables and use these with a bottom timer.

The relative merits of technical (multimix) diving computers have often been discussed on this forum.

Since the majority of the people I will be diving with will be using tables it makes little sense for me to spend £800 on a device I will never use properly because I will always have to wait around for my buddy to complete his planned deco schedule in any case!

I still have an open mind and my attitude is technology has its place but as far as technical diving computers are concerned they are currently as reliable as a model T Ford, but a breakdown could be fatal.

They will improve and be accepted given time.

 

[The Iceni]

Dr Deco once bubbled...
Some of the data is in the ATTACHMENT and shows the reduction in microbubbles after a zero, 60, and 120 minute waiting period. These nuclei were generated by physical activity (deep knee flexes.) { Dervay JP, Powell MR, Butler B, Fife CE. The effect of exercise and rest duration on the generation of venous gas bubbles at altitude. Aviat Space Environ Med 2002 Jul;30(1):22-7 }[/font] Dr Deco :doctor:

Hi Dr Deco,

I am getting a little confused. On some of your earlier posts you recommended gentle cycling exercises during decompression to improve offgassing owing to increased cardiac output.

Was the exercise performed during this study (deep knee flexes) performed on the surface in a chamber under the influence of gravity, ie. isometric exercise = harmful.

As I understood it, performing isotonic exercise when submerged during deompression stops is beneficial and does not generate such excessive micronuclei.

Could you please clarify?

 

[SCUBAMedic]

Dive computers are just a tool for your brain to use. They don't stop your brain from working, you choose to stop your brain from working. I am getting a bit sick and tired of the same old argument computers verses tables. Both are only as safe as the person using them - use what works for you, if your new try both, become good with both of them, then decide for yourself.

Uncle Pug - your type of diving is not for everyone, there are many ways of diving - using a computer is only one of them. Using a computer is a great way of monitering asent rates and done properly you can look around you keeping your awearness, watching little bubbles and stuff in the water and comparing that with what your computer is saying to give you an even better understanding and in the case of failure simply switch to either your backup or start to monitor the environment. Which you already know the speed of, because you have always been comparing it to the computer assent rate reading.

I am one of those people who started out with tables and moved onto computers, they are a good tool - but they are only as good as the brain looking at it.

 

[Uncle Pug]

SCUBAMedic once bubbled...
I am getting a bit sick and tired of the same old argument

Cheesy: whining about being sick and tired of a thread you chose to read.

If you are sick and tired go to bed... or at least learn to read thread titles and stay away from the ones that make you sick and tired....

Sheesh... somebody really needs to learn situational awareness.

Uncle Pug - your type of diving is not for everyone

Sure it is. Ask anyone who has ever been diving with me.