@stuartv stage cylinders are just as important in backgas. In fact, the dive we went on with the gear above, the only thing we used backgas for was inflation as that was our bailout from the DPV's and a few breaths during gas switches. The dive was conducted essentially exclusively on the stage cylinders
Understood. And, in that case, if I had a transmitter (or multiple) to use, I might put it (or them) on stage bottles, instead of back gas. My diving is not at the level of using extra cylinders like that, yet, so what I "would" do is speculative. However, I *think* that I would do just what you've talked about - which is simply NOT spend extra money to put transmitters on every cylinder. They're just for convenience and data collection. I'd use the transmitter(s) I had on the cylinders that would be my highest priority for convenience and/or collecting data. MAYBE if I were to someday get to a point where I was diving with that many cylinders on a very frequent basis, but that's too far away for me to worry about.
Right now, I'm pretty happy to just have one transmitter for my back gas (with an SPG as backup) and only a 1" button gauge on my one deco cylinder.
You two can't keep your mouth shut? Like I said keep it low! Shut up and wait!
More seriously now, one of possible problems I see, how is GTR/deco relation implemented? Since SW computers are regarded as great tech computers, and there is consensus that dive training is in a decline over time, how many of incompetent divers would be tempted to try more demanding dives on a premise: it is all fine, I know how much gas time I have by looking at my computer?
I know of some divers that are kept back only be need to calculate their remaining bottom time vs available gas. Take that away and they would start pushing it.
There are plenty of computers that have been available for a while that would do just what you're talking about. It's not like Shearwater is breaking new ground here. There are even Trimix-capable AI computers that have been out for a decent while.
Those divers you're worried about could have been doing what you're talking about long since, if they wanted to.
And, my opinion, the relationship between GTR and the deco implementation is not rocket science. The computer knows how many psi/minute you're draining. It tells you how many minutes until your current tank gets to 500 psi or whatever reserve you set it for. Some current implementations base that calculation on staying at your current depth. Some base it on current depth plus your ascent.
In other words, assume your computer is telling you you have a GTR of 1 (and you configured the computer for a 500 psi reserve). On some computers, that means you have 1 minute at your current depth before you hit 500 psi. On other computers, that you means you have 1 minute until you need to begin your ascent, at 30ft/min, in order to hit the surface with 500 psi left. You are responsible for knowing how your computer works and what the GTR means.
I think all (semi-modern and newer) computers support doing deco. I.e. Even if you exceed your NDL on a Suunto Zoop or Mares Puck or whatever, it's going to tell you when to stop on your ascent and how long to stay there. So, they ALL know what your expected ascent time is and what your average depth will be during your ascent. So, they can all easily calculate how much gas you will consume during the ascent, assuming you continue to breathe the same way you have been. I think the Oceanic AI computers base your consumption rate on how much you have consumed in the most recent 90 seconds. But, every AI computer could be different in the details of that.
Anyway, it will be interesting to see the details of Shearwater's AI implementation. Do they let you configure a reserve in psi? Do they base your GTR on when you'll hit the reserve or is it when you have to start your ascent to hit the surface with your reserve? If you have a deco gas configured, is the GTR the time until you have to start your ascent in order to reach your first gas switch with the configured reserve left?
Anyone who makes diving decisions based on the GTR that their computer is telling them and hasn't read the manual to know exactly what the GTR means on that computer is an idiot.
