Air Integrated Computers "Could Potentially Kill You."

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The value of air integration varies according to the needs of the individual diver. I will describe those differences by describing myself in terms of (1) the diver I used to be, (2) the diver I am now, and (3) the diver I may become in the future.

1. I joined ScubaBoard in 2004, and I had been using an air integrated computer (Suunto Cobra) for 5 years at that time. I was purely a vacation diver with maybe 125 total dives. Those dives all occurred during vacations to tropical resorts, with long periods of inactivity. I had no diving theory knowledge beyond my AOW certification. When AI debates arose, I chimed in, describing why I liked mine. It was nice to see everything I needed to know in one place, but I had other reasons. I learned to adjust my dive based on how fast I was going through air. When I looked at the dive time remaining and didn't like what I saw, on most dives I could change that simply by ascending a little. Even though I had never heard the term "SAC rate," I was learning all about mine, and I learned through experience what to expect during a dive.

2. Today, the overwhelming majority of my dives are open circuit, back mounted technical dives or shallow training dives teaching that. I take oodles of gas on those dives, so I know that if all goes as it should, I will finish the dive with a healthy reserve. When I am doing single tank recreational dives, I know that I will probably surface with more than 1,000 PSI. Thus, almost all my dives end (or change direction) when the planned dive time is reached, not when I reach a certain gas level. Consequently, I only need to check my gas a few times during the dive, just to make sure everything is going normally. A catastrophic gas leak will announce itself through sound without any need for an SPG check. As a result, I don't see any reason to spend the big bucks to get air integrated computers (I dive with 2), so I don't own any air integrated computers.

3. Several years ago, my enthusiasm for cave diving diminished significantly when I was on an exploration team and one of our divers died. I have been thinking about getting back into it, and if I do, I will be doing it mostly while sidemounted. The need to switch tanks during a sidemount dive increases the need to know your current gas levels, and it is a PITA to see those levels via SPG. Cave dives are usually turned on pressure, not time, so it is important to know your pressure levels. Right now, with the little bit of cave diving I do each year, I am content to use SPGs, but if I decide to go into it more, then I will be switching to air integration.
 
SPG is there at hand, and is much more readable. I usually watch the computer only when I am back at 9m, and it is time to evaluate if some deco is required, and in case how long...
You don't know if you need to do any deco or how long it will be until you reach 9 m?
 
Rly? I find making such causal connections.pretty intuitive. I'm not sure I understand what you're saying here.
In a previous post Angelo said that his usual plan goes like this: he knows that his "normal" SAC is 13lt/min and plans his dive accordingly. Then towards the end of his dive he checks his remaining gas, and if it is far less than the expected one (meaning that the actual SAC for that dive was more than "normal") he pads accordingly his deco obligations.

My reply was referring to this. As I said a computer, just by monitoring SAC, cannot know what "normal" SAC is before the dive (average SAC of previous dives wouldn't work here for several reasons), hence the computer can't know when one's SAC deviates from "normal" during the dive accurately enough to make deco obligation decisions based on this. I think you agree up to here - if I make myself clear enough.

Later Angelo brought the example of Scubapro-uwatec computer(s) which is another can of worms (apart from gas, they also monitor heart rate).
 
Later Angelo brought the example of Scubapro-uwatec computer(s) which is another can of worms (apart from gas, they also monitor heart rate).
The uwatec system appears to give you the choice of using heart rate or respiration (or neither). With both, it looks at your heart or breathing rate during the first few minutes of the dive to determine what "normal" is.

Now, personally, I find that my breathing rate during the first few minutes of a dive is always a good bit higher than my normal resting rate during the rest of the dive.
 
Now, personally, I find that my breathing rate during the first few minutes of a dive is always a good bit higher than my normal resting rate during the rest of the dive.
The would be true for me for most dives, including especially dives where I have to...
  • pull down a descent line in current to reach a wreck.
  • get geared up into doubles and clamber down a set of stairs to get to a platform where I will finish gearing up, etc.
  • swim along the surface to start a descent. (I once had a buddy thumb the dive after our surface swim--he felt too spent to continue.)
  • get all my gear out of the vehicle, carry it to the entry point, gear up, etc.
 
Now, personally, I find that my breathing rate during the first few minutes of a dive is always a good bit higher than my normal resting rate during the rest of the dive.
That's exactly the problem. The computer needs strong input to make right decisions (BS in BS out). All these "methods" are based on assumptions. In the case you describe the assumption is that whatever rate we have during the first few minutes of a dive is used as reference for the rest of the dive. Another horrible "method" could be to use previous dives' SAC rates (maybe their average) but here it is assumed that the conditions over the previous dives will be similar to the next dive (very often not true and hence that's why this is a horrible idea). And so the story goes.
For us humans it is quite "easy" to guesstimate averages. Discard this dive I hadn't rested well the night before, forget that dive were my octopus was leaking, and the other one we hit unexpected strong current and so on. Then group the rest of the dives to similar conditions and average the SAC for each group. Worst case if the estimation proves wrong for few dives we re-evaluate.
Like Angelo, in more or less well known conditions for 100s of dives he knows that his average SAC for easy going dives, is 13lt/min and whatever deviates from this needs to be addressed.
For a computer that needs to be able to perform from dive #1 that's not easy at all. Imagine for example a computer with a warning like this in the first page of the manual: "Caution: only to be used after (say) 10 successful 10 dives".
 
I like AI because I can get rid of a hose, and I can check my air, depth, and NDL at a single glance. I do it often because it's easy to do and it gives me a useful snapshot of my dive situation. And since I have a pretty good idea of my basic parameters at all times, if the computer goes black I can proceed to the surface with minimum of drama.
Others may use another system that they feel comfortable with and that's just fine. In my catalogue of modern day hazards the failure of AI is pretty far down the list.
 
Thanks for the useful info received.
So in the end the AI computer is not better than my old way of evaluating extraordinary workload, and to augment deco times accordingly.
At this point I really do not feel any reason for swapping my cheap Leonardo with an expensive and powerful AI computer.
In no way I will remove my vintage SPG from my MK5+109. I could screw the transmitter in the second HP port, or on the other MK5 feeding the second 109, but it would be an unnecessary redundance. My computer is console-mounted with the SPG, and I do not like to have anything on my wirst, apart the watch. So watching the computer means also watching the SPG, which is analog and much easier to read.
I do not think that an AI computer is dangerous, as I will always have my trusted SPG.
Simply, there would be no advantage, just another small number on a display which is already trying to show me many other numbers...
 
At this point I really do not feel any reason for swapping my cheap Leonardo with an expensive and powerful AI computer.
From what you describe with your diving, I wouldn't switch to AI, either. As I noted earlier, I don't feel the need to spend the money for it now. If my circumstances change, I would make the change, but right now, I don't need it.
 
If (and that is a very big IF) I would ever get a transmitter, it would be on a port pointing downwards, on a first stage that is angled (as they typically are on a DIR setup).
There is absolutely no way that transmitter would be at risk of catching onto anything that my valves or first stages wouldn't have caught on to ages before that.
I would never put it on a hose as that would just be an extra failure point to me, but to each their own.

Some people like to see potential "failure points" in every bit of kit. I don't see having the AI transmitter on a hose as posing any greater risk than an SPG on a hose.

In recreational (as opposed to cave) scuba diving, possibly the bigger risk is having the AI transmitter attached directly to the first stage. If you are diving from a boat where you de-kit in the water and the boat guys or skipper haul it inboard, you don't want them grabbing the AI transmitter instead of the valve knob. Attaching the AI transmitter to a short HP hose addresses this issue, and tying it bending it down addresses the risk of bumping it in a wreck, pass thru or overhead environment.

YMMV
 
https://www.shearwater.com/products/perdix-ai/

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