What happens when AI fails?

[jeraldjcook]

That's amazing. An LDS that actually doesn't recommend the most expensive gear. Even with the bad advice your shop sounds like a keeper. I have a Pro Plus II and love it. If AI fails, abort the dive.

 

[Scared Silly]

Funny I have the opposite reaction about the dive store. I would probably find another cause they do not know what they are talking about. So who knows what else they are selling based on misinformation.

As others have said if the transmitter fails you abort the dive just like if anyother piece of equipment fails. All of the wireless AI wrist units are made so that they can be used without one . Many people do just that because many times the wrist unit has more features than others - for instance the Suunto Vytec DS. The early transmitters did have some reliability issues but they are largely solved. I personally worry more about deck dorks dropping a tank on my second stage than the transmitter.

BTW I have both an spg and a transmitter - I use the transmitter to log my air usage cause I am too damn lazy to do it after the dive .

 

[johnny_bravo]

My Suunto Vytec's transmitter failed for one dive this weekend (I also own a D9). The computer worked just fine it just gave me the normal dive time left instead of "air time". I used my analog gauge (that's what it's for as a backup) for air pressure.

I'm thinking of ditching the analog backup. Like others have mentioned in this thread if it fails for the recreational diving I do I simply end the dive and ascend slowly. If you are paying attention you should know rougly how much air you have.

Cheers.

-J.-

 

[cummings66]

I'm not aborting my dive if my AI fails. I have my primary gage that's not likely to fail and I'd just continue reading it. If they disagree on the amount of air I have I'll abort, but not if it's a clear cut transmitter failure and I lose the link.

I use the AI to note and log tank pressures and in that regards it's very handy. I tend to think the transmitter is more accurate than my SPG is for what that's worth and it reads less than the 250 psi increments my analog gage does. I know I can get gages that read 100 psi but 250 is good enough for me because halfway between is 125 psi.

To answer your question, the computer would not lock up if the transmitter stops.

I've got this stray thought bouncing around in my head, I don't know what to do with it so I'll come out with it.

We rarely have backup depth gages and rely on the computer or gage to provide that data, knowing we'll abort the dive if at any time it fails. We have a similar situation with the ai here, if it fails why not simply abort the dive then and there? You should already have a clue how much air remaining there is, and hopefully you've included your buddies air supply into the figure. So why is it that people freak when you say you've dropped your SPG and use AI only?

In both examples I gave of depth vs air supply you abort when there's a failure so where is the argument I'm not seeing? I'm honestly asking here, I'm probably overlooking something.

For my diving I'll dive with a SPG and I'll treat it as my primary information source with the AI backing it up. If there's a disagreement I'll believe the one with the least amount of air and abort. But why do I do that? Is it because I believe analog will never fail? I know that's not true, I've had analog gages in my plane fail on me. I've had digital give me bad information on the TV's I repair. I kind of rationalize that by having 2 different sources of air pressure I'll have a feel for what's right.

PS, I dive a VT3 and love it.

 

[thomjinx]

I have never heard of a failure mode for a dive computer where if the transmitter fails, the whole computer stops working. I can't imagine that anyone would engineer/design one that way. All of the wireless AI computers that I have ever heard of can be used with or without the transmitter. Some people buy the AI-capable computer without a transmitter and add it later, as their budget allows.

 

[xiSkiGuy]

I recall someone telling me that one of the old Cochran AI computers had the computer integrated with the transmitter and the wrist unit was just a receiver of sorts. The Cochran transmitter unit in question was massive and screwed into the HP port and then clipped onto your reg hose. I've never used this one, so I don't know if this is accurate.

None of the current generation AI computers that I am familiar with "fail" in that way. In fact, in 90 or so dives with my Uwatec SmartTEC AI computer, I have yet to notice that I have lost signal. YMMV.

EDIT- I was thinking of a Cochran Gemini http://www.divecochran.com/computers/Gemini/index.html , but it appears that at least the current version (and perhaps all versions) also can function independently.

 

[CompuDude]

I have the SmartTEC also. Wireless AI, no problems. I recently added an SPG in preparation for tech diving, but I don't bother with it during the dive, because I never have a problem with my AI.

If the computer lost the link, you would lose your air pressure and estimate of time remaining, but all other functions continue normally.

AI is a nice little luxury. You can live with it, you can live without it. But don't live without it due solely to bad information. A LOT of people dive every day with AI computers with zero problems.

 

[Scared Silly]

I tend to think the transmitter is more accurate than my SPG is for what that's worth and it reads less than the 250 psi increments my analog gage does. I know I can get gages that read 100 psi but 250 is good enough for me because halfway between is 125 psi.

DO NOT confuse measurement accuracy and measurement precision with numerical precision (digits). Just because one can get more digits from a digital gauge than an analog gauge does not mean in any shape or form that the digital measurement is any more accurate or precise than an analog gauge. Further, even if one can 5 digits from a digital gauge it does mean that all five digital are significant.