Worth extra $ for air intergrated computer?

[TheRedHead]

Would you really continue a dive, without knowing how much air you've got left?

I know how much gas I have within 200 psi without looking. Depending on the circumstances, I might continue a dive if it were fairly shallow.

 

[dannobee]

I'll add this. If you happen to be into photography, the alarm by itself might be worth it. You can program the thing to beep at a turn pressure or at any myriad of other warnings to suit you, including the all-inclusive "dive time remaining." I know some picture takers get lost in the moment and for some of them the AI thing adds a bit of safety.

I have a Pro Plus 2 and an Aeris AI (basically the same computer, just packaged differently) for AI's, and have another setup with a hockey puck and an SPG. The AI is easier to glance at and get all of your info.

 

[ChrisA]

It seems to me like the only advantage to air integrated over regular SPG and computer is the remaining dive time.

No, not even that. The remaining dive time that is displayed assumes that you will continue to breath air at the current rate. If you change depth your rate of air usage changes or if you turn around and swim up current you usage will change. So it turns out to be just a toy.

Where it is useful is if you want to analyze your dive later and compute things like SAC rates. You need to know your SAC rate so you can plan dives better. The air integrated computer helps you keep the records you need. Of course a dive slate could also do it "good enough".

Even if you do buy the air integrated computer a smart diver will still have a real mechanical SPG as a backup.

 

[TxHockeyGuy]

Just curious... I'm assuming you equate "crack your SPG" with an out-of-commission guage...

Would you really continue a dive, without knowing how much air you've got left?

I would under very specific circumstances. The dive site would have be shallow, both myself and my buddy would have to be familiar with it, and we would need to know our air consumption rates in relation to one another. Using a rough guestimate based on our relative air consumption rates I would plan on being at the surface with at least 1000 psi in both tanks. I consider this a big enough safety margin, I'm sure many if not most here will probably disagree. I certainly consider my proposed method safer than diving the old J-Valves and starting your ascent when you hit 500 psi which people used to do all the time.

In fact I have done this when my buddies air integrated computer failed and he had no backup spg. We knew he had a much better air consumption rate than myself and the last known readings showed him having much more gas than myself. We had already turned the dive and simply continued on. We did end up surfacing earlier than originally planned for an additional margin of safety which resulted in a longer than planned surface swim. I'm sure many consider this unsafe and I respect that opinion, I simply don't share it.

Edit: This is one reason why I want to add an AI computer to my current setup. I'll then have redundant computers and redundant air "gauges".

 

[BKP]

The best feature of an AI computer is that the software will calculate your SAC. Then you can track your SAC with types of dives done (looking for exertion level, cold water, etc.) and that might help you with gas planning in the future. The assumptions an AI computer make about how much time you have left in terms of gas are faulty. It is usually holding back a reserve as well.

Yes, it will.

However, if you note your starting and ending pressure, most of the download software will do that as well, without buying the AI. (Not that I'm anti-AI... will probably go that way myself sooner or later, and keep the SPG as a backup).

 

[BKP]

I know how much gas I have within 200 psi without looking. Depending on the circumstances, I might continue a dive if it were fairly shallow.

I'm envious... Seriously...

I have a short-term memory like a sieve, and can't remember the readings from thirty seconds ago... I have a short-term memory like a sieve, and can't remember the readings from thirty seconds ago... I have a...

 

[Matsya]

snip.................
The assumptions an AI computer make about how much time you have left in terms of gas are faulty. It is usually holding back a reserve as well.

Would it be correct to say that the asumptions are "conservative" rather than "faulty"?

 

[Tienuts]

Would it be correct to say that the asumptions are "conservative" rather than "faulty"?

Faulty would be the better word. Like someone posted before, the AI comp measures your SAC rate by the change in your tank pressure. A change in your breathing rate from exertion or a change in depth will screw it all up. My VT pro has this feature, and I shut it off, since every small depth change I made would make the alarm go off.

And speaking of alarms, I teach my students that when diving on an AI computer, to minimize and turn off all non-essential alarms. It's the "cry wolf" theory. If alarms keep going off, eventually you will train yourself to ignore the important one.

 

[TX101]

How much is the $200 worth to you? If $200 isn't much money, then why not? If $200 takes more than a day to earn, then save your money.. It's not essential by any means, but it's useful for post dive analysis when you download your dives and log them on computer. It will calculate SAC automagically too, which I consider to be the best feature.

I have a uwatec smart com (console) computer and use it on most rec dives, unless my wife is diving. I then use an suunto SM36 spg and a dive rite nitek 3. Although the sm36/nitek combo gets me more "techy respect" when on the boat, I actually prefer using the smart com.

And to the guy who says it's a failure point because you must end your dive early, that's true with a mechanical spg as well... And how many people carry a spare spg in their "save a dive" kit?

 

[bperrybap]

Faulty would be the better word. Like someone posted before, the AI comp measures your SAC rate by the change in your tank pressure. A change in your breathing rate from exertion or a change in depth will screw it all up. My VT pro has this feature, and I shut it off, since every small depth change I made would make the alarm go off.

Dive Time Remaining should change if you change depth
or your breathing changes - I don't see this as a screw up.

You may not like the method it uses or its algorithm but
I wouldn't call it Faulty at all. It is doing what it is supposed to do.
The Computer is not really measuring or calculating a SAC rate.
It is looking at Air pressure change over
time and estimating how long until the air is gone -
or at least until some set point is crossed which can be a
predetermined pressure.
SAC does not come into play for this calculation; it is not needed.

Alarms go off when a user settable threshold is crossed which
could be pressure or an estimated time remaining.

Where I've seen the really annoying alarms come into play is
if you set an alarm based on XX minutes of time remaining.
Once that alarm goes off (if it was based on air),
if you go up, the dive dive time remaining may rise above
the XX setpoint and in a short while you end up crossing back
through the XX setpoint again which generates yet another alarm.
Depending the XX value, and your dive profile, this alarm
may trigger multiple times.

Another annoying one is trying to use the END pressure alarm
as a early low pressure warning to indicate it is time to
start wrapping up the dive and end the dive.
It is not meant for that. This alarm can retrigger over and
over, especially when it is set a few hundred PSI over
where you intend to finally ascend.

Certain combinations of alarms can be worse. Like combining
a DTR alarm with an END pressure alarm. Some computers
also have builtin alarms around 500 PSI that you get whether
you want it or not.

I believe that the Dive Time remaining is quite useful and
the computers do a pretty decent job at calculating this.

The way some of the AI alarms work, now there is an
area that could probably be tweeked to be more useful and
less annoying.

Better descriptions of how the alarms work, interact with each other,
and your dive profile would probably help a lot.

Some of it is learning how the alarms work and
how to best use them. Some folks still may not want them.
For example,
rather than completely disabling all the AI alarms there are
ways to eliminate nearly all of them (if thats what you want)
yet still get a low pressure warning. You can
use the TURN pressure alarm as a nice low pressure alarm.
Since the air pressure will only cross through the TURN pressure
once, it will not repeat like some of the other alarms can.
So you could set this to say 800 or 1000 PSI if you wanted
to get a single "low pressure" alarm.

Overall, I'm a big fan of AI, Dive Time remaining,
and certain AI related alarms.
Some alarms can be quite annoying, depending on how
they are used.

--- bill