Air integrated computers…backup?

[doctormike]

There have been very recent threads on this.

History is made by those who show up.
--Woody Allen

I saw the truth in that statement many times over my lifetime, especially on committee assignments where the decision made would have been entirely different if certain individuals had not shown up one fateful day.

It happens on ScubaBoard as well. People ask a question like this one, and the first couple of pages set the tone, and that tone is determined by who shows up in those pages. The same question can be answered in different ways in different threads.

This can also be a function of time. About 6-7 years ago, someone started a thread asking tech divers what decompression software they used. I would guess the answers ran about 80% VPM. A couple weeks ago someone who had been out of diving since those days asked the same question on the Cave Divers Forum and was stunned when not a single person favored VPM. What was once the dominant program was now passé.

The same is true for air integration in general. Threads on that topic today are quite different from threads only a few years ago.

Exactly.

Another important consideration is that scubaboard is a SOCIAL forum. That is, the whole point of the thing is to get divers talking to each other. It's not some repository of expert knowledge like an encyclopedia, where you just visit to look up the "correct" answer. There's a lot of nuance and personal preference that comes out in the conversation, and each conversation is different.

Plus, many of us just enjoy the dialogue itself, since we might not be able to actually dive right now, and talking to other scuba divers is a nice way to pass the surface interval.

Yes, it gets tiring typing the same points out again and again, but anyone who feels that way is under no obligation to participate in a new thread.

 

[Hoag]

What if?
If the only SPG fails you lose the tank pressure and call the dive. A spare SPG will let you know the tank pressure and make the ascent easier.

A single gas pressure monitor, whether SPG or transmitter is fine for most dives.

You are absolutely right. It is absolutely fine for most dives. And not having a spare tire (or a way to seal a puncture & refill your tire) is absolutely fine for most drives. The thing is though if your primary fails, it never hurts (and some may view it as good planning) to have a "Plan B".

 

[Belzelbub]

No, there is nothing in the Teric or VT3 download that reflects the dead transmitter battery. The VT3 has no battery information in the download. The Teric has computer battery information, but no transmitter information.

View attachment 718073

I don’t believe Shearwater Cloud displays the info, but that doesn’t mean that the computer doesn’t save that info. My Perdix does.

Subsurface has a field for T1 transmitter in “Extra Info.” It doesn’t give a voltage, but I don’t believe that the transmitter sends that level of info. Most likely only normal, low, critical. I’ve only seen normal in my log, so guessing on those other two.

The Oceanic most likely doesn’t, though. In my log where the VT4.1 was used, there is no T1 transmitter field in Extra Info.

 

[Belzelbub]

You are absolutely right. It is absolutely fine for most dives. And not having a spare tire (or a way to seal a puncture & refill your tire) is absolutely fine for most drives. The thing is though if your primary fails, it never hurts (and some may view it as good planning) to have a "Plan B".

So, I take it you use two SPGs on a single first stage by that logic.

 

[Byrdie]

Yes. AI on the wrist computer and a backup computer with SPG in the console.

 

[OMyMyOHellYes]

Two Perdi AI and two Swifts. If one of anything craps or one of each craps, I'm good to keep on goin..... Both computers, or both swifts, have to crap to leave me in deep doodoo.

OMMOHY

 

[Centrals]

What if?
If the only SPG fails you lose the tank pressure and call the dive. A spare SPG will let you know the tank pressure and make the ascent easier.

A single gas pressure monitor, whether SPG or transmitter is fine for most dives.

I know that part on calling the dive with a single spg failure but I never seen/known anyone diving with two spg on a single tank or even twin(back gas).
A lot of 1st stage has only one HP port.

 

[Joneill]

No, there is nothing in the Teric or VT3 download that reflects the dead transmitter battery. The VT3 has no battery information in the download. The Teric has computer battery information, but no transmitter information.

View attachment 718073

What kind of batteries do you use as some like the Energizer Ultimate Lithiums have a very flat discharge curve that means they can die pretty quickly wilh little or no advanced warning:

https://data.energizer.com/pdfs/l91.pdf

Shearwater talks about the fuel gauge for the Petral in this video and I’d assume the same is true for transmitters:

 

[Canajan]

On my doubles, spg is on then left post and the AI xmitter is on the right post. Even with an isolation event, should still have enough info to get to the surface.

 

[Belzelbub]

I know that part on calling the dive with a single spg failure but I never seen/known anyone diving with two spg on a single tank or even twin(back gas).
A lot of 1st stage has only one HP port.

Right. And that was largely my point. Diving with a single SPG is fine in just about everyone’s eyes. I never see anyone calling for diving with two on a single 1st stage. Yet, I hear plenty of people insisting that diving with a transmitter requires a backup SPG.

Dive with an SPG if you want. Dive with two SPGs if you want. Dive with a transmitter and an SPG if you want. Dive with just a transmitter if you want. They are all fine. I just don’t get the need to dive with both a transmitter and an SPG.

And not having a spare tire (or a way to seal a puncture & refill your tire) is absolutely fine for most drives. The thing is though if your primary fails, it never hurts (and some may view it as good planning) to have a "Plan B".

I’m quoting this again because the analogy is a bit flawed the way I think it was intended. My truck has a full sized spare. My wife’s car does not as it has run flats. But that wasn’t the point I wanted to make.

If my truck has a flat, I pull over and change it. This is analogous to surfacing and swapping the transmitter for an SPG (or just changing the transmitter battery) on the boat. Diving with a transmitter and SPG would be more like driving and having a tire that when flat seals and refills without having to slow down. Run flats aren’t the same as there is a limit to how far you can drive without air in the tire.

I’m a firm believer in having a Plan B. My truck has a spare tire. My boat trailer has two spare tires and a spare hub. My boat has a spare engine. All are there to get me back home without having to call for help even if it takes a bit longer.