Does everyone really need an SPG? (w/transmitter)

[Belzelbub]

OK. But that wouldn't be ideal if someone paid $100+ to do a 2 tank charter. If you're shallow shore diving like me, it wouldn't matter so much. Plus if it's really shallow (30') you probably don't need a DC anyway (or even an SPG).

True. The same could be said for an SPG malfunction. Most don’t carry two. Yes, I know SPGs don’t malfunction all that often. Likewise, my transmitter has been pretty reliable.

If I were doing a charter, I’d at least bring an SPG in my bag. I do have a spare at home. First, I’d change the battery, so I could do dive two.

 

[CosbySweater]

If you use a transmitter, odds are at some point in your diving career it's going to malfunction. I had the battery go on a Suunto transmitter without warning at depth. Suddenly my wrist mounted AI showed <100 psi at 80 feet. I carry a backup AI computer (hard lined, not a transmitter) that allowed me to continue the dive and do the next dive without issue. Had it not been for the backup I would have been done for the day. I'm a believer in carrying at least a backup SPG if you use a transmitter. Carrying a fully redundant hard lined AI computer is even better IMO. I spend a lot of time and money to be underwater so I like to reduce the number of things that will ruin a dive or a boat trip. To each their own, though.

 

[Divin'Papaw]

I spend a lot of time and money to be underwater so I like to reduce the number of things that will ruin a dive or a boat trip. To each their own, though.

Amen! I came pretty late to AI so keeping a simple brass & glass SPG was a simple and easy decision. I keep it on a hose just long enough to attach to my left hip. I don't even know it's there but can reach it and unclip it if I ever need it. If the AI on my Perdix were to fail during a dive would it kill me? Certainly not but it would cause me to adjust my dive in a way that I choose to avoid. With my luck it will be the end of that dive that I had to cut short when that whale shark, great white shark, manta ray or other cool critter would come along! I have a backup computer (non-AI) as well on every dive. Neither my AI or my computer is going to cause me to have to miss part of a dive or a dive entirely.

 

[scubadada]

Amen! I came pretty late to AI so keeping a simple brass & glass SPG was a simple and easy decision. I keep it on a hose just long enough to attach to my left hip. I don't even know it's there but can reach it and unclip it if I ever need it. If the AI on my Perdix were to fail during a dive would it kill me? Certainly not but it would cause me to adjust my dive in a way that I choose to avoid. With my luck it will be the end of that dive that I had to cut short when that whale shark, great white shark, manta ray or other cool critter would come along! I have a backup computer (non-AI) as well on every dive. Neither my AI or my computer is going to cause me to have to miss part of a dive or a dive entirely.

I dived @JimBlay current set up for 9 years. I did not need it many times, it always came through, no interrupted dives Does everyone really need an SPG? (w/transmitter)

 

[shoredivr]

Seen AI fail to pair up twice, and AI fail
in the middle of a dive. The first two cases resulted in no dives. The other meant the dive cut short.

 

[Pressurehead]

I think I posted this before on this subject, a search could not find it.
Took the SPG off when I first had AI on a computer for few dives, BUT muscle memory kept me looking [feeling] for it every dive and not the computer,
Gave into it and did not fight it , a glass and brass SPG went back on [with my 2 computers, one AI].
Old dog and new tricks come to mind.

 

[Mike1967]

BUT muscle memory kept me looking [feeling] for it every dive and not the computer,

Fair call, I'm the opposite. I've had AI since my 5th dive, kept wearing my SPG for another half a dozen or so, it lives in my save a dive kit now.

 

[gamon]

If you use a transmitter, odds are at some point in your diving career it's going to malfunction. I had the battery go on a Suunto transmitter without warning at depth. .

You gotta watch it when you make sweeping generalizations based on your own subjective and personal experiences.

What @CosbySweater wrote is simply not true. Several assumptions are made that don't follow a logical thought process.

I've got almost 500 dives on air integration, my buddy has 140, with no failures. So I could post that air integration is extremely reliable.

If your non-AI computer fails, you might have to abort the dive anyway depending on your no decompression limits, and you'd lose all your nitrogen and oxygen data from an extended dive trip (if applicable of course) and that applies to both air integrated and non air integrated setups.

I had a wrist receiver flood (I don't count this as an air integrated malfunction) and I continued the dive but stayed close to my buddy in the event that I would need to use their gas, but I always have a good idea of how much gas I have remaining so I can fairly accurately estimate dive time remaining. Worst case scenario my reg breathes hard at the safety stop and I cut the dive short and surface and attach my good old SPG that is currently sitting in my gear bag. I've had it on and off my first stage several times and finally decided not to bother with it anymore.

So a dive doesn't necessarily have to be aborted with a computer failure of any sort.

I too spend a lot of time underwater and I prefer to have all the information right there on my wrist without dragging an extra hose and set of gauges, it makes diving that much more enjoyable for me and if I HAD to abort a dive due to the extremely low possibility of an AI failure and no other option to extend the dive, it would still be worth it to lose one dive out of 100s in exchange for the convenience of wrist mounted AI.

 

[kmarks]

I bought an AI computer when I started diving and added a second computer in 2015 when my wife quit diving. When I started teaching, I added an SPG to my bag as a backup, just in case my AI pod went out right when I really needed it. I put the SPG on my first stage one day last summer when I got a "Lo b" warning from my AI on our first dive one morning and never took it off even after changing the battery. It, and the second computer, served me well when my primary/AI computer started acting up immediately and with no warning upon descending over the SS Milwaukee last summer, the first dive of our trip. I was able to just switch my attention the other other computer and use my analog SPG without losing any of my dives that weekend.

 

[Jake 10]

To Corrupted;
To answer your question, every diver has a choice if they need it or not. I keep one as backup.