To use a back up SPG or not?

[skankpile]

I dive with two Cochrans (20H and a Gemini) and never have connection issues as its top shelf with internal redundancy and not outsourced to the lowest Chinese bidder. You should always know how your air is within 250 psi. If you have it on your wrist its an easy glance so no big deal.

If I'm worried about air I'll sidemount and have redundant everything. I'd rather sling a 40 than have an extra spg.

 

[James R]

On recreational dives, I do not have a brass/glass SPG. I do take one with me on a trip, but it stays in my bag. I monitor my air every few min so I know pretty much all the time how much I have remaining. If it fails, I can easily make a safe ascent without any drama.

If I am doing a technical dive, I put my transmitter on my right post reg (pointed down toward the tank, not up!) and my brass/glass stays on my left post. I do check the brass & glass and AI before the dive starts to make sure they match and then another time or two, starting about 15min in to make sure they still match.

My current AI (Luna) has hundreds of dives and still works great and has never had a failure or lost signal. I would like OLED screen and bungee mount, though...

By the way, it's pretty scary that some people forget to sync up their transmitters before jumping in. Do you guys have brass/glass SPG too? I would think that before starting a dive it's a good idea to check to make sure you didn't just get in the water with an empty tank. YMMV, I guess.

 

[fnfalman]

I have a spare SPG in my save-a-dive kit to use if and when my hoseless AI computer were to funk out.

I change batteries on both the computer and the transmitter every January, the same time I VIP my tanks. Batteries and O-rings are cheap.

In four years of diving, three of which with hoseless AI computer (Aeris Elite T3), I only had it funked out on me once and it was because the shop technician bungled the O-ring when he screwed the cap back onto the battery compartment of the computer. The battery compartment leaked yet the computer still worked throughout the dive, albeit at a very light appearance and I had to angle the computer to see the display. It shut down after I finished my safety stop. I went up to the surface, whipped out the SPG and depth gauge. Already have the watch on my wrist. Went to town for the next three dives.

Nowadays, after the battery change, I make the shops do a pressure test right then and there.

 

[StuartT]

I also dive the aeris t3 and use a back up spg clipped off to my bottom left d-ring on my bcd. I have never looked at it during a dive until last Sunday when for some reason my transmitter kept losing the link to the wrist mount. First dive with my reg after being serviced. I'll get my service tech to have a look at it. First time in over 250 dives had issues with the link. Battery checks all good on the wrist mount and both transmitters (primary reg and pony reg). The back up spg became invaluable for that dive and the next one otherwise would have had to call the dive and be done for the day. I also use a second backup wrist computer for added redundancy. For the record also only do recreational diving. I don't even notice the spg/hose while diving so I would recommend having one.

 

[fnfalman]

I also dive the aeris t3 and use a back up spg clipped off to my bottom left d-ring on my bcd. I have never looked at it during a dive until last Sunday when for some reason my transmitter kept losing the link to the wrist mount. First dive with my reg after being serviced. I'll get my service tech to have a look at it. First time in over 250 dives had issues with the link. Battery checks all good on the wrist mount and both transmitters (primary reg and pony reg). The back up spg became invaluable for that dive and the next one otherwise would have had to call the dive and be done for the day. I also use a second backup wrist computer for added redundancy. For the record also only do recreational diving. I don't even notice the spg/hose while diving so I would recommend having one.

Make sure that the replacement batteries are of brand name manufacturers. I had a hell of a time getting some of the generic batteries to work. Other posters have explained it in the Gauges/Computers subforum. Something about generic batteries may have the same voltage but they don't have enough impulse to work with these dive computers.

Anyway, I changed my batteries from XXX to Panasonic/Duracell/Energizer/Sony and they worked like a charm.

 

[633squadron]

I have a primary computer and a backup, both wrist-mounted. To keep things simple, the backup is not air-integrated, and so I carry a Halcyon SPG.

I've had the pressure sensor on my primary die on me at least twice, once when I was on a trip out of the country.

 

[Akimbo]

Here is my opinion: Use the SPG until the computer proves itself to you. That may be one dive, ten dives, or never. Confidence in your equipment is more important than the added bulk.

 

[imwright1985]

i dive with Hoseless AI and have the trans drop occasionally. I base it on my last check time and what the gauge is flashing at. if its been a little while, and link wont come back on, where im uncomfortable i call the dive. I dove with the SPG and AI for a few dives and saw i lost link once for about 10 seconds so i took the SPG off and keep it in my bag (ready to be swapped out) so a bad day with AI wont ruin my day of diving.

Couple things i consider are if im going in overheads i take AI and SPG, If Im having alot of issues I would add the SPG. I havent had enough issues to make me add it though and with going in overheads its a better safe then sorry issue, just tuck the SPG away and try to forget about it (It annoys me a bit though) but have it there for emergency.

 

[AfterDark]

Hoseless gauges IMO expensive gagets that have no real world benefits. In close in places where less hose means less chance of entanglment, most divers use a SPG for backup I've used the same SPG now for 25? years. NEVER failed that is NEVER failed. When hoseless can make that claim then maybe I'd consider spending that kind of money. Keep It Simple Stupid KISS a concept to live by especially when diving.

 

[highdesert]

To the OP ... I see nothing wrong with your thinking. My wife/buddy and I have both had failures with AI computers on a hose. We've replaced those, but now have an SPG and secondary wrist computer for full redundancy. I've had more "experienced" (opinionated) divers here on the board snicker at me for doing so, but I'm happy with the plan, confident in it, and will stick with it.