Question Backup dive computer

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edwants2dive

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I had an issue with my Aqualung I770r the other day between dives for some unknown reason it froze up saving the dive profile 10 minutes into the SI. I didn't have a backup computer but did the second dive on gauges loaned to me from the dive operation ( used 45 min bottom time @ 80 ft 35% nitrox table to do it). I didn't go on the afternoon dives I had scheduled that day because of the issue even though the dive op offered to rent me a computer. I just felt that it was better to call the day than to keep diving without the complete mornings profile on the computer I would have rented. That said I want to get a backup computer just incase this happens ever again. What I am wanting opinions on is should I get one with the same algorithms for NDL or not really worry about that part? I don't intend to get an AI model as I have a backup SPG already. I would setup the backup and take on the dives with me but only to use it to continue a day's diving should the primary ever lockup again.
 

Kimela

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I was wearing a backup with a different algorithm than my primary and hit my NDL without realizing - because I wasn't paying attention to it! My primary was a heads-up-display and I never even looked at my wrist computer that was just there as 'backup'. So either make sure they're both set for similar algorithms or dive according to your most conservative computer. Don't be Kimela. Don't get yelled at by the captain!!
 

Tracy

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Now is your opportunity to buy a Peregrine and have an awesome backup computer than you can tailor the algorithm to closely match what you are already diving.
 

rhwestfall

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I bent my (then) back-up which was in my pocket while my main computer worked through the dive....

Try to find something that is running a similar algorithm....
 

BoltSnap

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I had an issue with my Aqualung I770r the other day between dives for some unknown reason it froze up saving the dive profile 10 minutes into the SI. I didn't have a backup computer but did the second dive on gauges loaned to me from the dive operation ( used 45 min bottom time @ 80 ft 35% nitrox table to do it). I didn't go on the afternoon dives I had scheduled that day because of the issue even though the dive op offered to rent me a computer. I just felt that it was better to call the day than to keep diving without the complete mornings profile on the computer I would have rented. That said I want to get a backup computer just incase this happens ever again. What I am wanting opinions on is should I get one with the same algorithms for NDL or not really worry about that part? I don't intend to get an AI model as I have a backup SPG already. I would setup the backup and take on the dives with me but only to use it to continue a day's diving should the primary ever lockup again.

If you are going to dive with the AL I770r again, then buy a low end AL dive computer to use it as a backup. The lower end AL dive computer are actually very good.

You need to find out why your I770r "froze" first however.
 

rhwestfall

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The other thing to evaluate is the idea of just missing the dive, and resetting your off-gassing clock for the next day....
 

scubadada

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Hi @edwants2dive

Your Aqua Lung computer runs PZ+ deco algorithm. It is a proprietary algorithm based on Buhlmann. Only another computer running PZ+ would have identical NDLs. PZ+ is moderate, or middle of the road, in the conservative to liberal spectrum. It runs somewhere near a Buhlmann GF high of 85. A more conservative computer would have shorter NDLs and would control your dive, unless you are willing to clear deco. A more liberal computer would back up any profile on your Aqua Lung. What backup computer are you thinking of getting?

Why did your Aqua Lung lock up? How long were you locked out before it ran again normally? There are not many reasons for a normally functioning computer to lock out, missed deco, violation gauge mode, is probably the most common.
 
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edwants2dive

edwants2dive

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Why did your Aqua Lung lock up? How long were you locked out before it ran again normally? There are not many reasons for a normally functioning computer to lock out, missed deco, violation gauge mode, is probably the most common.
I don't know why it locked up but I do know that it wasn't any of the reasons you mentioned as I watched my no deco time on that dive (all dives for that matter) and never got within 15 minutes of deco also did a full 3 minute stop at 15'.
After I got home that night I searched the internet to see if I could find some info on it and found an Amazon review from someone who had the same thing happen. I emailed Aqualung support the paragraph below today I will see how they respond.
"Support Team,
I have an I770R computer and transmitter with 57 dives on it. After the last dive it froze up 10 minutes into the surface interval with the screen displaying the message "saving dive data". I tried to get it to respond to button pushes but it would not. I let it sit for a couple of days until the battery completely died then plugged it into the charging cable until it was 100% charged back up. It now seems to be back to normal but I have not dove it since that day. I would like to know if this is a known issue or bug in the software version or is it possibly a defective device."
 

ATJ

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I normally dive with Shearwater Perdix AI and a Garmin Descent Mk1 both set to GF 40/85. While they are not identical, they are pretty close. I have also used Oceanic computers running PZ+. I find the NDL for the Oceanic to be pretty close to the other two computers so if you are happy with PZ+, any computer with Bühlmann set to 40/85 will give you a close match.

The big difference I have found is that if you drift into deco, it clears more quickly with the Bühlmann computers than it does with the PZ+. For example, I have cleared deco on both the Garmin and the Shearwater just by going shallower but the Oceanic wanted 8 minutes of deco!
 

Divin'Papaw

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I'm a believer in having both computers running the same algorithm. I don't want to have to monitor closely and essentially "dive" two computers that will invariably disagree, sometimes significantly. If the algorithms are too different, you risk violating and bending one of them. I therefore have two Shearwaters and I run the exact same algorithm on both. My primary is a Perdix AI and my backup is a Peregrine. Before this my backup was a Petrel, Before that I dove two Petrels. I've been diving the same algorithm on both computers for quite a number of years. I really like it that way and couldn't imagine having two computers that may disagree significantly in terms of NDL.
 
https://www.shearwater.com/products/perdix-ai/

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