Aqualung i300c Average Depth Calculation Issues?

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scrane

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Bottom line is, how can I trust that this computer calculates properly the tissue loading and all the other values if the average depth is not calculated properly? I emailed Aqualung and did not get an answer.

I would assume that Aqualung isn't very interested in spitting out Average Depth either. You can verify NDL by planning your dive by table and comparing it to the computer's readings, throwing in a fudge factor for algorithm mismatch. Or, you can probably rely on Aqualung's reputation for giving valid data on important parameters.
Average depth is a computed value based on depth and time and really doesn't have a lot to do with anything, especially the running tally of tissue saturation.
You are more at risk by improperly setting up or misinterpreting your computer than that computer failing.
 

scrane

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I KNOW my SAC, so it is easy to calculate my dive time at 20 ft. (2h, by the way)
But apparently you do not know YOUR SAC, so you have no way to calculate your dive time. Right? You said earlier you just dive 'til you run out of air. Not much of a "plan" for someone with as much experience as you claim.
So, we both came up with the exact same answer (my two hour, 20 ft safety stop).And if because I was fighting current and getting low on air I'd probably just call the dive at 1:58.
 

tursiops

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Average depth is a computed value based on depth and time and really doesn't have a lot to do with anything, especially the running tally of tissue saturation.
Average Depth has EVERYTHING to do with gas consumption. Running out of gas will give you a bad day just like DCS. Tissue saturation is NOT the only consideration.
 

tursiops

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So, we both came up with the exact same answer (my two hour, 20 ft safety stop).
LOL. You are just trying to justify your bad behaviour! How did you arrive at 2h?
 

wnissen

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The last column in your first table is labeled "Max depth", is it max or mean?
I realize this must seem nonsensical to some of you, but if your browser is exactly the right width the table cuts off with no sign that it continues. See picture below. If you scroll to the right you'll see some seriously messed up average depth values, like less than a meter.
Screen Shot 2020-09-27 at 9.25.10 AM.png
Bottom line is, how can I trust that this computer calculates properly the tissue loading and all the other values if the average depth is not calculated properly? I emailed Aqualung and did not get an answer.
I would not ignore it. While I agree that in general people misuse and misunderstand their computers far more often than those computers malfunction, the computer producing bad data could be the one time in 10,000 where the problem actually is the computer.
Let's assume that the problem is that it's counting the surface interval as part of the dive, and also that the actual average depth is 79% of the max, as it was on your first dive. (0*28+.79*15.9*52)/(28+52) = 8.2 meters. Yet it reports the average depth as 5.5 meters. I calculate your actual average would have had to be 53% of max in order to get 5.5 meters. That's a pretty shallow dive. Something really screwy is going on.
 

RIHappyDiver

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Bottom line is, how can I trust that this computer calculates properly the tissue loading and all the other values if the average depth is not calculated properly? I emailed Aqualung and did not get an answer.

Bottom line is even if the computer IS calculating everything else properly, you WON’T trust it. Even beyond that, the computer is malfunctioning. I had 2 pre C series i300s that had to go back to AL. You will need to go to the dive shop you bought it through. If you bought it on line you need to make friends with your local AL dealer. They will need to get a RMA from AL, after which either one of you can ship it off to AL. If you bought it on line I recommend that you offer to ship it so the shop is not eating the expense, or buy a new tank, or something that leaves you in their good graces, because it will be shipped back to them and you don’t want it sitting on a shelf somewhere for a month.
Good luck,

Erik
 

scrane

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I would bet that if you send back a computer that is misrepresenting just average depth it will return to you in the same condition. Outside of the depth transducer and the time constant everything else is firmware based. If you have a valid complaint about a vital firmware bug a manufacturer might issue an update.
 

dannysporea

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I would not ignore it. While I agree that in general people misuse and misunderstand their computers far more often than those computers malfunction, the computer producing bad data could be the one time in 10,000 where the problem actually is the computer.
Let's assume that the problem is that it's counting the surface interval as part of the dive, and also that the actual average depth is 79% of the max, as it was on your first dive. (0*28+.79*15.9*52)/(28+52) = 8.2 meters. Yet it reports the average depth as 5.5 meters. I calculate your actual average would have had to be 53% of max in order to get 5.5 meters. That's a pretty shallow dive. Something really screwy is going on.

Bottom line is even if the computer IS calculating everything else properly, you WON’T trust it. Even beyond that, the computer is malfunctioning. I had 2 pre C series i300s that had to go back to AL. You will need to go to the dive shop you bought it through. If you bought it on line you need to make friends with your local AL dealer. They will need to get a RMA from AL, after which either one of you can ship it off to AL. If you bought it on line I recommend that you offer to ship it so the shop is not eating the expense, or buy a new tank, or something that leaves you in their good graces, because it will be shipped back to them and you don’t want it sitting on a shelf somewhere for a month

That's what I was thinking initially too, but after making the same calculation, it did not make sense to me either. I was trying several ways to figure out how those numbers were calculated, but the more I tried the more I come to the conclusion that the computer is wrong... The downloaded dive profiles look good and match what I remember from the dives, so I believe the pressure sensor and the depth in the profile is correct, just the average values seem out of whack. But again, probably I should not trust this computer anymore and find a way to send it back to AL. It should still be in the 2 years warranty period, just that I bought it online... will try to find a local dive shop willing to help me out.
 
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