Thinking of moving from AI to non-AI but...

[Knot4Sail]

I’m presently using a Uwatec Aladin Air and plan to take a nitrox course soon. Of course I’ll have to buy a new dive computer.

I’m thinking about going with a wrist computer and an analog SPG rather than AI this time. Just too many trips back to the dive shop, all related to the AI. What I’m not certain of, as I consider this change, is exactly what dive data will be missing or less accurate on a non-AI set-up and it’s relative importance to safe diving. I’ve been reading dive computer manuals on line till I’m blurry eyed and I’m still not sure about some things.

Typically, on an AI set-up, tank data is in the lower window or at least on the lower portion of the display. I’d like to know what displayed data in the upper part, has tank data included in the calculation? For example, isn’t remaining bottom time at current depth a result of factoring in tank data? On a nitrox computer wouldn’t displayed nitrogen and O2 absorption values be factored, in part, by breathing rate? If so, then how does a non-AI computer accurately display these values? Kicking into a current will certainly cause faster absorption so how does one justify going with non-AI?

I’m looking, not so much for specific answers to my questions as I am insight into understand why the lost data should be considered less critical than I think it is now.

 

[Uncle Pug]

Do an experiment.

On your next dive (may it be soon) check your time, depth and tank pressure upon reaching the bottom. Check again in exactly five minutes and make a mental note of your depth and tank pressure. Don't worry about remembering it at this point... just mentally note it. Do this every 5 minutes and not at random times more or less than 5 minutes and do not check in between the 5 minute checks. On the 15 minute check guess your PSI before looking and make mental note of how close you came. From then on before checking make a guess and see how close you come. If you were swimming harder between 5 minute checks then factor that into your guess and see how close you come.

BTW... if you are swimming hard you are not diving... you are swimming! Relax and become one with the water. You will see your gas consumption rate plummet.

You will also see that you do not need an AI computer to figure out how much time you have left on a tank. You won't have to figure... you will just know.

 

[ChrisM]

Ditto to Uncle Pug, I practice predicting my pressure, and try to be within 100-200 pounds either way, I'm usually pretty close if I am paying attention.

I went from an AI Cobra to a Vyper and analog gauge a few months back. Other than retraining my eyes to read the dial vs. the numbers, I don't miss a thing

I pretty much know from my usual SAC rate and profile how much time I've got.

On a nitrox computer wouldn’t displayed nitrogen and O2 absorption values be factored, in part, by breathing rate? If so, then how does a non-AI computer accurately display these values? Kicking into a current will certainly cause faster absorption so how does one justify going with non-AI?

The answer to the first question is no, so the answers to the rest are irrelevant. The ONLY function affected by breathing rate would be time left. Both NDL and 02 absorption are based on theoretical models

Chris

 

[scubatoys]

The answer to the first question is no, so the answers to the rest are irrelevant. The ONLY function affected by breathing rate would be time left. Both NDL and 02 absorption are based on theoretical models

Chris

Actually depends on the computer... Some will take breathing rate changes into consideration and back off allowable nitrogen times based on temp, breathing, and profile behavior... like saw tooth profiles. Neat?? Yes. Useful or proven beneficial... Not really.

 

[ChrisM]

Actually depends on the computer... Some will take breathing rate changes into consideration and back off allowable nitrogen times based on temp, breathing, and profile behavior... like saw tooth profiles. Neat?? Yes. Useful or proven beneficial... Not really.

Ah, thanks for the heads up.

I can safely say that not once did I look at the dive time remaining on my Cobra

Chris

 

[jdr159]

My wife and I both use AI computers (Oceanic Datamax Pro Plus and VT Pro). I prefer an AI simply because I only have to look at one instrument to get all critical info. I don't know your skill level, but personally I run out of bottom time before I run out of air (stricly recreational diving), so air time remaining is not critical info, just convenient..

Finally, I would question that an AI computer is more fragile than an Non AI. They all essentially have the same base electronics: The AI have an added pressure transducer..

The real question to me would be cost: AI are typically 3x non AI...

Good luck.

 

[Knot4Sail]

Thanks guys for the input.

jdr159, I haven't been diving all that long (61 dives) almost all in cozumel. Make 2 or 3 trips a year and do 2 or 3 dives per day. I thought taking the nitrox course would be good so I've been shopping for a new computer. The Aladin had problems but never really caused an abort. One problem I had twice was with the quick disconnect which I see as essential for boat dives there because they keep my gear and I want to keep the computer overnight. I thought a wrist computer and an analog SPG might be a good alternative but then I began to wonder what else the air integration does besides what the SPG does. As Larry points out, some AI computers adjust on gasing values based on various factors, breathing rate and profile behavior which non-AIs can not do. I thought this capability should be a factor in deciding which way to go because I can those factors in my diving in Cozumel. Kicking vigorously into a strong current to hold to take pictures, moving up, down and through tunnels and walls are pretty routine. Other dives are just drift with the current so they do vary. The question still in my mind is how much would the non-AI and an AI differ. Larry says the adjusted amounts have not proven beneficial and I'm not smart enough or experienced enough to question that. However, if important enough to capture and display NDL and 02 then why not buy the one that is most accurate. Maybe it would make a difference after 5 days in taking a hit or not.
So, I'm about ready to go with AI again. I was looking at Larry's site considering the Atmos Elite but read where it can be used with or without the transmitter. So, I'm thinking this one does not pass tank data to adjust dive data and the manual doesn't say.The manual doesn't say. Makes sense that it would not if it can be used without the transmitter. Back to square one.

 

[freedive]

Hi knot, may I make a suggestion if you go the comp/spg route, if you haven't done so already you might want to consider the Uwatec Pro Ultra and SPG set up. It will be the same interface as your Aladin Air so you already know how to use it, same datatrack use (if you have the memo mouse) and it will also take care of all your nitrox needs. This is the set up I'm currently using and so far (30 dives) it's been flawless.

Juan