Computer only dives?

Since I've started recreational diving, I've been needing to beg, steal and borrow gear, gradually working my way into buying my own. Now it's time for the gauges/computer. Is it reckless abandon to go strictly AI computer, with a single module monitoring cylinder pressure, depth, bottom time, etc? I know we could "what if" everything in this world to death, but sticking to the root issue, is it safe and prudent to dive with only a computer, as far as gear goes?

I know lots and lots of people that dive with just an AI rig. Personally, I have a Vytec AI, but I also dive with a pressure gauge. Some thoughts:

- My SPG is a back up. My SPG is alo mounted facing out so my buddy can sort of slide up next to me, scan how much gas I have, and slide back into formation.

- As you get in the groove, you should get into the habit of scanning your gauges about every 5 minutes or so. I do it a little more frequently at the start of a dive, then settle in for about every 5.

- As you do this, you should start estimating your gas usage. I've got it to where I can estimate (at various depths, various levels of exertion, etc,) to anywhere from spot on, to a couple of hundred pounds either way.

- This is part of being engaged in the dive... knowing your gas supply before you look. It will also deliver great confidence and peace of mind, should your AI ever go south on a dive (not likely.) In that event, you calmly and slowly surface, because you know what's in the can.

FWIW - I have hundreds of dives on my Vytec. Never one failure with the AI. They're pretty solid.

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Ken

IMHO, properly used, no. You should not depend on it to do your gas management (ie, it says I have XX minutes remaining), but used as Mo2vation suggests they're fine. If I was buying, I like the Sherwood Wisdom. Nice shape, large numbers, user replacable battery, Nitrox capable, can connect to your PC. Do get the one with quick disconnect.

SDI Open Water Certification relys on AI Computers only. It's one of those things, the longer it is around the more people will accept it. Not only do the computers display minutes, they also display pressure just like a gauge. So, just like a gauge, if the computer were to break underwater, you should have a good idea how much pressure you had before since you monitor it and start to accend towards the surface. Gauges break too, and you should always abort a dive if you have an equipment malfunction.

I dive with an AI only and no backup... never been a problem. I prefer the Aeris footprint to the sherwood, but both are great.

I dive with a Vytec AI computer, but I also use a hoseless pin gage for checking pressure without my computer. A pin gage is the kind of gage you often see on spare air or deco bottles, It's a small gage that threads right into the HP port on your regulator.

One of the advantages of an AI computer is removing a HP hose from your setup, using a pin gage gives you another way to monitor cylinder pressure without adding an extra HP hose or turning on your dive computer.

Its probably not imprudent, but, IMHO, it is an utter complete and utter waste of money that could be better spent on more useful items.

I bought an Aeris 500AI a few years ago. It told me everything that I could possibly need to know, including how many minutes I had left, a couple of cute bars for O2 and N2 loading and, by pressing a button, my pressure. I used it for a couple of seasons, then decided that I really didn't need all that information and that I really wanted the pressure to be displayed without needing to press any buttons. I also realized that I could predict how long I had left on a tank.

What really convinced me to stay away from AI machines was a mistake that I made and a problem that I observed. In my case, I found out the hard way that the Aeris does not activate upon contact with water. Instead, it must be manually activated. I was on a boat dive. I activated my computer, then got delayed getting in the water. The computer was on when I was getting ready, but apparently turned itself off before I hit the water. I didn't notice (stupid me) and got to the bottom before I found out that it wasn't working. Even worse, it cannot be activated deeper than 4 feet. I wasted a good part of the dive going back up to reactivate the computer.

The problem I observed was on another wreck dive. Another diver had a hoseless AI on a wreck dive. The receiver repeatedly lost the signal, which created difficulties for the diver because he did not have an accurate pressure reading. Subsequent calls to the manufacturer led to the fascinating discovery that the presence of large amounts of ferrous metal can interfere with the signal (FWIW, I only observed this once, and received my information second hand from the diver)

I replaced the Aeris with a Suunto Mosquito and an OMS SPG. That provided me with all the information I wanted (depth, pressure, time, ascent rate) for about half of the cost of the Aeris.

Like Northeastwrecks, I tried AI and decided it just is not worth the $$$$. And because they change so quickly, you may well be looking at a new one every 5 years or so. A good SPG will last a lifetime (or 2). Stand alone computers for depth, time, N and O status are about half the price and will provide all the info you need. And the upgrade to the newer model, if you must, will also be about half the price. I guess if the dive is really boring, all that extra info you can get from an AI rig might give you something to do.

Northeastwrecks:

I found out the hard way that the Aeris does not activate upon contact with water. Instead, it must be manually activated.

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That was the good old days... you used to have to use a phone line to access the net too... but today, all of the ones water activate - it's actually a feature you can turn off it you don't want it to, but the default is, as soon as it gets wet... it turns on.

awap:

And because they change so quickly, you may well be looking at a new one every 5 years or so. A good SPG will last a lifetime (or 2). Stand alone computers for depth, time, N and O status are about half the price and will provide all the info you need. And the upgrade to the newer model, if you must, will also be about half the price. I guess if the dive is really boring, all that extra info you can get from an AI rig might give you something to do.

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Actually you wouldn't need to upgrade it any sooner than an SPG unless there is a new feature that you want, just like any other computer. They don't wear out.

And the additional info from the AI being right at your fingertips makes it great for interesting dives because you don't have to spend a lot of time fumbling around and making miscalculations in your head because it is all done for you.