question about dive computers

[dmbelina]

I was talking with my LDS today and they said that with an AI computer, your dive times are longer than using a non-AI computer.

I forget exactly what it is he said, but it was something about non-AI computers are basically computerized dive tables. If you were planning on diving 50ft for 70 minutes, and 15 minutes into your dive you look down and you're at 80ft, bam (that's what he said, heh), you just shortened your dive to 30 minutes (total time, so you only have 15 minutes left now), even if you were at 80 feet for only a few seconds.

With AI computers he said they take into account how much you are breathing, along with depth. And some stuff about how different tissues absorb nitrogen at different rates. If the situation above happened, it would take into account the time spent at 80 feet, and if you went back up after only 30 seconds at 80 feet, your dive would be shortened, but not nearly as much as with a non-AI computer.

This is what I got out of his explanation.

Did I misunderstand? Can someone clear this up?

Thanks!

 

[DiveTub]

Both AI (Air Integrated) and Non AI from the same manufacturer will usually use the same algorithms to work out your no deco and deco limits.

The difference is a AI computer has a second window that displays tank pressure and on some models time left at your current depth before you must ascend to finish the dive with a certain amount of air in your tank usually around 30bar.

As oppose to a non-AI computer that you have to work out in your head with your SPG to finish your dive with the same amount of air.

You have the same amount of air in your tank so regardless what way you go you can still stay at the same depth for the same time. Both AI and NON AI computes will show you how much no deco time you have left and all will credit you for ascending to a shallower dive.

A Good example of this are the Uwatec Computers
http://www.uwatec.com/index1.html

Cheers
Chris
MSDT
http://homepage.mac.com/sydney_diver

 

[Scuba]

An Air Integrated computer is able to calculate your air consumption, then, based on how much air you have left in your tank calculate how much dive time you have remaining.

This is something that a non AI computer can not do since it does not know how much air you have in your tank.

Most new computers ( regardless of AI or not ) will calculate how much actual time you spend at a certain depth as you move about, ( sawtooth profile: repeated ups and downs ) as opposed to penalizing you for your maximun depth regardless of time spent there. They then use different guidelines to determine your nitrogen and in the case of Nitrox, oxygen exposure. The result is some will be more conservative in their calculations reducing sligthly your bottom time as compared to the more liberal guidelines.

Does a readout telling you how much air time you have left make your dive last longer? Based on other considerations ( DCS exposure, safety gas margin needed in your tank, etc ) I would say this is immaterial. A computer that can calculate the example in the third paragraph is the one that will give you more bottom time.

Peter

 

[Uncle Pug]

The difference between an AI and non-AI computer is the rate at which your brain rots.
Guess which one rots your brain faster.

 

[JDostal]

I have an AI computer, and I never use the Remaining Bottom Time feature...I like to dive based on tank pressure.

And your LDS telling you that an AI computer calculates the times better than a non AI is BS. They both use the same algorithm, they both will take into account your short time at a deeper depth. And both can do detailed dive profiles.

The air integrated is nice in that it gives you another check on your own dive plan...that's about all I use it for. Otherwise, when I'm at depth I don't look to it to see how much time I have left. I use the tank pressure to see how much time I have left.

 

[redacted]

They want to get deeper into your pockets and they are willing to feed a new diver whatever line of crap they think will work to seperate you from your $$$.

Not that AI is not a good feature, but the cost outweights the benefits in my (check)book. And each time you upgrade you get to buy the integrated SPG again.

I would look for a seperate computer with the features you need & a new dive shop to do business with.