SPG with AI computer?

[Divin'Papaw]

To each their own, but having an SPG has saved quite a lot of vacation dives for me. The primary thing I haven't seen discussed here is the ease with which you can diagnose the issue that has caused an AI failure. Perhaps I just got very unlucky, but I had what I thought was my Swift AI transmitter fail while diving down in FL. Tried switching out the battery and that still didn't resolve the issue. Mailed the transmitter back to Dive Tronix, and they replaced it - but that still didn't fix the issue as the same thing happened again in Curaçao. Finally figured out that the issue was actually a broken antenna on my Teric.

If I hadn't had a backup SPG I definitely would have lost ~4-6 dives, and in addition would have had to spend time scrambling to figure out replacement gear while travelling.

If you only dive local, and don't mind thumbing the odd dive, then I can see why folks don't see a need for redundancy. However, as a travel diver who only gets a handful of dives per year, the redundancy means all I lose if something fails is some RMV data and the inconvenience of not having air readout on my dive computer.

I agree fully. This is why I have an SPG in my backpack on the boat. I can install it in about 2 minutes if my transmitter or computer have an issue rendering AI unusable. This is also why I always had a spare SPG and spool with me back before diving AI. I didn't have them on the dive, but I had them available on the boat (or onshore if a shore dive) if needed.

 

[Rearviewmirror]

As I was reading this, I was trying to guess what type of transmitter and computer you were using. When you mentioned Swift, I guessed it was a Teric. While still pretty rare, there have been more than a few antenna problems on the Teric. But, I agree, if you've had issues with your current setup, a backup does make sense. I use a Perdix and have used a VT4.1 before. Both have been extremely reliable.

This didn't fail underwater, right? Sounded like it happened pre-dive. In that case, I would have simply installed the SPG and did the dive. I'd troubleshoot later. I have kids that dive, and they have the same transmitters, so I could definitely rule out a DC problem. In your case, I'm almost positive your Teric would have read the pressure had you held the Teric right up to the transmitter.

This was the slightly insidious nature of the problem I experienced - don't want to derail this thread but a brief synopsis. Initially the AI would show data on tank pressurization on the boat, and then would disappear once I splashed. After replacing the battery I had the exact same issue, after replacing the transmitter I got zero signal at all (which is what let me know it was the Teric). The fact it wouldn't always fail, and only seemed to drop connection once I submerged made this a bit of a tricky one to diagnose, but luckily with my SPG could still continue the dive once I had splashed and didn't have to reboard the boat to switch out for an SPG.

 

[Bigbella]

It goes to an over-arching dependance upon electronics -- and it is a bit telling, that of all of the open circuit solo and closed-circuit divers that I have known over the years, both in sport and industry, with their often colossal array of electronics -- multiple computers, HUDs and transmitters, none failed to carry simple analogue SPGs with their kits.

I am no Luddite by any stretch and own several transmitters -- now, actually one fewer, after a Shearwater model, subject to a recall a few years ago, crapped out at forty meters, apparently due to interference from another transmitter which hadn't happened earlier; but the dive went on, thanks to a combination analogue depth gauge and SPG that I had had for years, clipped to my BC.

Here is a Cyklon 300, now often used on a pony bottle, my first regulator, that I have had since the late 1970s, along with a Shearwater transmitter from around 2021 — heh, heh, a forty-year plus, marriage of new and old tech . . .

 

[BoltSnap]

I started using hoseless AI dive computers in mid 90s and never used SPGs in open water since then. The only time I use an SPG is in the pool when teaching since I have a different kit for pool. I used AI with hose and hoseless computer combinations at different times but I always used hoseless AI since then. There were some reliability issues early on but it was computer issues not AI issues. Currently, I use two different AI dive computers with two different transmitters (Ratio and SP). I can't see me using an SPG except if I am required to do so.

 

[BoltSnap]

I can ditch weights and manually operate a BC to some degree, and swim without fins.

Not really (unless you are joining the special forces and going through their training).

I can't conceive of breaking or losing my mask, but I could ascend without it fairly decently if I had to I imagine, even with a safety stop.

Much more experienced divers than you are carry a spare mask if there is a chance they would lose their mask. You won't be able to do what you think you can do easily or safely.

and a computer watch with AI seems to have a lot more potential failure points, even acknowledging the advancements in reliability.

Not really.

I guess I question whether I'd want to cut a $100 dive short because I didn't have an additional 10 ounces of backup.

Get a second AI computer with transmitter if you are that worried

 

[scubadada]

For a variety of reasons, I have used my SPG on 17/1814 dives, 0.94%, in the last nearly 13 years. I have never cut a dive short or missed any dives. I will keep it. I have replaced the spool on my SPG a couple of times due to leak, I keep a couple in my save a dive kit. My SPG is completely out of the way on my left chest D-ring

 

[KenE]

I was just considering removing the SPG from my kit. Been diving both for a couple years and felt confident with the AI. Then on the next dive I experience a battery failure that showed a consistent 2356 psi on my computer. After the second look and no change in gas I realized the AI is dead. The SPG allowed us to continue the dive without aborting five minutes into the dive. A battery change fixed it, but the SPG saved an early abort. So, until I get more confidence that the AI will not fail me, I will keep that SPG clipped to my waist D-ring.

 

[Boarderguy]

I was just considering removing the SPG from my kit. Been diving both for a couple years and felt confident with the AI. Then on the next dive I experience a battery failure that showed a consistent 2356 psi on my computer. After the second look and no change in gas I realized the AI is dead. The SPG allowed us to continue the dive without aborting five minutes into the dive. A battery change fixed it, but the SPG saved an early abort. So, until I get more confidence that the AI will not fail me, I will keep that SPG clipped to my waist D-ring.

What computer and transmitter? I've never heard of that. Sounds more like something blocked your transmitter input and was cleared when you changed the battery... def an oddity

 

[Divin'Papaw]

I was just considering removing the SPG from my kit. Been diving both for a couple years and felt confident with the AI. Then on the next dive I experience a battery failure that showed a consistent 2356 psi on my computer. After the second look and no change in gas I realized the AI is dead. The SPG allowed us to continue the dive without aborting five minutes into the dive. A battery change fixed it, but the SPG saved an early abort. So, until I get more confidence that the AI will not fail me, I will keep that SPG clipped to my waist D-ring.

Tip. The battery is one key failure point on AI transmitters, but it is very manageable. I have all of my AI transmitters on a regimented battery replacement schedule. I replace them proactively well before their theoretical battery life. YMMV.

 

[BoltSnap]

Tip. The battery is one key failure point on AI transmitters, but it is very manageable. I have all of my AI transmitters on a regimented battery replacement schedule. I replace them proactively well before their theoretical battery life. YMMV.

Or get a Ratio transmitter and computer that give you long lasting rechargeable transmitter battery