Air Integrated Dive Computers and SPG's

[fisheater]

I have a glass and brass SPG clipped to my left waist D ring and an AI wrist computer. Though I've never had the AI computer fail, I've had the SPG fail (drop from a bench onto a concrete floor in Bonaire). So, each backs up the other.

Dive on!


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[ScubaGil]

Hi,
Thought I'd share that last month I spent 2 weeks on a liveaboard and had the Transmitter fail 4 times pre-dive and once mid dive. I will replace the battery (even though it is not telling me to) and see if that helps, and after each failure it went back to working great. In any case I'm adding an SPG to my setup as I lost confidence in the transmitter. I'll keep the transmitter on my setup though as it is nice to see air consumption rates once I download the data.

Best,
Gil

 

[dallaskincaid]

Hi,
Thought I'd share that last month I spent 2 weeks on a liveaboard and had the Transmitter fail 4 times pre-dive and once mid dive. I will replace the battery (even though it is not telling me to) and see if that helps, and after each failure it went back to working great. In any case I'm adding an SPG to my setup as I lost confidence in the transmitter. I'll keep the transmitter on my setup though as it is nice to see air consumption rates once I download the data.

Best,
Gil

What computer were you using, if you don't mind me asking? Any chance that it was interfering with another wireless computer?

 

[ScubaGil]

What computer were you using, if you don't mind me asking? Any chance that it was interfering with another wireless computer?

Hi,
I was (and still am) using a Suunto D9. I was the only one on the boat using a wireless transmitter. The strange thing was that on one of the dives where it failed pre-dive it all of a sudden started working once I started my safety stop. From my perspective the technology is not there yet, and will keep on diving with both SPG and transmitter as I said before.

Hope this helps....

Best,
Gil

 

[TSandM]

My husband uses a Vytec with a transmitter, and has definitely had some dives where the thing just won't sync. He uses an SPG . . . If you're content with not diving if it won't sync, and aborting a dive if it fails mid-dive, you could go without, I suppose.

 

[SanDiegoSidemount]

Having your gas pressure on your wrist is a great convenience, and tracking your SAC rate on the computer is awesome. When I dive my single tank setup, I use AI, right alongside my trusty old brass 'n' glass.

But I own SPGs that have worked great for over a decade with no maintenance other than a fresh water rinse. If your SPG is going to fail, it will most likely happen when you pressurize the first stage. Or when you drop a tank on it.

Batteries (and there are 2 of them in an AI setup) die. Housings can leak seawater into electronics. Wireless links can fail due to interference/environment. We've seen these discussed above. Any of these can happen at any time, potentially leaving you scratching your head at depth.

Other computer failures can be recovered by sharing your buddy's computer, which should have the same depth/time for the dive as yours, and allow the two of you to finish the dive safely if your computer fails. Gas pressure doesn't work that way.

 

[scubadada]

The AI computer topic has been discussed many times on SB, would likely be very easy to find additional threads

I have 339 dives on an Oceanic VT3 since July 2010 with no failures. I've changed the battery once so far. I've lost linkage perhaps a half dozen times for no more than 30 seconds. I'm generally unaware of the linkage losses but they are recorded on the dive log and you see them when you review your dives. Based on my own experience, I'm quite confident in the performance of my AI computer. As above, I really like having an accurate SRMV for all of these dives, calculated automatically for me by the download software.

That being said, I carry a back up Oceanic Geo2 computer and a SPG. The Geo2 runs NDLs nearly identical to my VT3 (DSAT algorithm) and the SPG reads almost the exact same pressure as my computer, maybe 25 psi more. I've never needed the 2nd computer or the SPG as backup but would hate to interfere with a great series of dives on a vacation or even a single dive for that matter.

Good diving, Craig

 

[pdhenry]

With the additional SPG they can carry on the dive normally even if the computer does fail, so the redundancy does have a benefit.

Depends on what fails, though. Right?

If the only thing that fails is tank pressure you're probably OK with an analog SPG as backup, but if the computer battery dies, even having a backup depth gauge probably means you're not diving your plan as a minimum. Did you check your NDL on the RDP before diving, or did you expect the computer to be there until the end of the dive?

My analog backups would be there to help me abort the dive safely. If it's the first dive of the day I'd need help calculating a safe second dive on an RDP if the first wasn't planned that way - bottom time & depth, etc. Even if you fix your computer it probably isn't reliable for planning the next dive since it wasn't there for the first.

Or not, tell me where I'm wrong.

 

[Scubanoobi]

I decided to scrap the SPG last year after testing out my new AI comp and realizing that after 20 or so test dives that it did not lose a signal. Sure enough the transmitter failed shortly after and I lost a dive. In my case the entry was close to a strong power source that interfered with the connection. Bottom line is anything can happen and having a backup SPG is a good idea. I now have the SPG.

 

[FinnMom]

I've had a transmitter for about 3 years now. Both my Vytec DS and HelO2 "talk" to it. There have been maybe 6 days in 3 years that the computer just can't find the transmitter's signal for no good reason whatsoever (everything worked several hours later), an one incident where it lost it 5 mins into the dive. None of these was an incidence of low/dead batteries or breakage etc., something just didn't feel like performing exactly then & there.

That's often enough that I would at least carry a SPG & hose plus necessary tools if I ever dared to remove the SGP & hose completely. I don't want to miss a dive and if something is going to fail I would expect it to be the fancy stuff.