Computer shutdown

[Unbent]

So we loaded all our gear, checked my tanks, EAN 32, and got under way for our trip out to the wreck. After the breakwater when things were calm I turned on my computers and set them to 32%. We got to the wreck approximately 30 min later, the DM dove to tie us in, and after 15 min returned to the boat saying the viz is NG.
we move to a shallower wreck he dives, ties in, says 6' or less but dive.
Gear up, ready to splash, safety check computers are shut down, push bottom, splash.
Dive 1 no issues other than poor viz, till buddy ran low I come out 73' 23 min.
1 hour safety stop exactly, splash, never thinking to check computer settings, why would I, I set them already.
Dive 2 much better viz buddy ran tank down to 500 in 13 min chasing a fish, I take him to up line and hang at 57' for remainder of dive. Computer shows plenty of time left, I still have 1600 lbs, I ascend.
Dive 2 shows 82' for 32.
On the ride in I fill in log book using PADI EAN 32 tables I am 1 min in deco, " why didn't my two computers tell me?" I scroll an they are set to AIR.
How, why, apparently when they shut down from not diving they set back to air, and I didn't check. Lesson learned

 

[Tigerman]

Umm.. The tables does not account for multilevel, which is why your computers dont show deco even on air when your nitrox table does.
If you would infact have been a minute into deco on 32% with the computer set to air, it REALLY would have told you as, air == less no deco time than ean32(and it would have locked up when you violated it, most likely)...

 

[doctormike]

So we loaded all our gear, checked my tanks, EAN 32, and got under way for our trip out to the wreck. After the breakwater when things were calm I turned on my computers and set them to 32%. We got to the wreck approximately 30 min later, the DM dove to tie us in, and after 15 min returned to the boat saying the viz is NG.
we move to a shallower wreck he dives, ties in, says 6' or less but dive.
Gear up, ready to splash, safety check computers are shut down, push bottom, splash.
Dive 1 no issues other than poor viz, till buddy ran low I come out 73' 23 min.
1 hour safety stop exactly, splash, never thinking to check computer settings, why would I, I set them already.
Dive 2 much better viz buddy ran tank down to 500 in 13 min chasing a fish, I take him to up line and hang at 57' for remainder of dive. Computer shows plenty of time left, I still have 1600 lbs, I ascend.
Dive 2 shows 82' for 32.
On the ride in I fill in log book using PADI EAN 32 tables I am 1 min in deco, " why didn't my two computers tell me?" I scroll an they are set to AIR.
How, why, apparently when they shut down from not diving they set back to air, and I didn't check. Lesson learned

I don't understand. If your computer was set to air, it would give you a shorter NDL than if it was set (correctly) to EAN32, not the other way around. Assuming that you are aware enough not to violate the MOD of EAN32, all that would happen if the computer got reset to air is that the computer would give you a shorter dive (or put you in deco) when you still weren't at your real NDL, right?

The fact is, having a computer that automatically resets to air is a safety feature. If the computer didn't reset to air, and you left it on EAN 32, forgetting to match it to the air in your tank on a subsequent dive, THEN you would be at risk of DCS, believing that you were still within NDL.

Also, the computer gives you "credit" for time spent above maximum depth, while tables don't, so even if your computer was set to the correct mix, you could easily calculate a deco obligation on tables while your computer showed that you were clear. I don't know if this was an issue for you, it wouldn't be with a square profile...

 

[Jim-SAR]

I'm not sure what kind of computer you have, but why did it shut off between dives? Is that normal?

I have an Aeris Atmos-AI and once it's been wet, you can't turn it off for 24 hours unless you remove the battery.


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[redacted]

Many computers will shut down after a period if it does not enter a dive mode. Mine shuts down 2 hours after startup and 12 hours after the last dive just to save power..

But I don't understand what the OP is saying about air versus nitrox and so much does not quite make sense.

The lesson that needs to be learned is that it can be dangerous to try to use a computer that you do not understand.

 

[Chilly_Dipper]

On the ride in I fill in log book using PADI EAN 32 tables I am 1 min in deco, " why didn't my two computers tell me?" I scroll an they are set to AIR.
How, why, apparently when they shut down from not diving they set back to air, and I didn't check. Lesson learned

Ok either you are explaining this poorly or you don't understand how NDL and Deco times are calculated at all. Lets start with the assumption you had a perfect square dive profile. If in fact your computer reset to air and you showed only 1 min deco on a nitrox table your computer would have been screaming bloody murder at you for a MASSIVE deco stop violation for being on air.

---------- Post added September 13th, 2013 at 12:24 AM ----------

I'm not sure what kind of computer you have, but why did it shut off between dives? Is that normal?

I have an Aeris Atmos-AI and once it's been wet, you can't turn it off for 24 hours unless you remove the battery.


Sent from my iPhone using Tapatalk - now Free

Dive computers are ALWAYS on, only the displays are shut down to save on battery power.

 

[FinnMom]

I thought pretty much all computers would automatically reset to air (or EAN 21 if in nitrox mode) after every dive.

I thought this was a standard safety feature to keep the user from inadvertently diving air w/ his computer set to an oxygen level greater than 21% (because diving air setting with nitrox in your tank is not dangerous, providing you don't inadvertently go too deep for that O2 %).

Then again I've only used maybe 4 different models of computer, all by Suunto, so my experience is pretty limited.

 

[doctormike]

(because diving air setting with nitrox in your tank is not dangerous, providing you don't inadvertently go too deep for that O2 %).

Correct. In fact, some people do this on purpose, for the added safety. I did for a while, after my chamber ride...

 

[Croomrider]

I thought pretty much all computers would automatically reset to air (or EAN 21 if in nitrox mode) after every dive.

Mine has a setting that allows you to turn this off (Oceanic Pro-Plus). If it is set to "off", it will stay at whatever EAN setting you have set from one dive to the next, with the exception of when it shuts off, in which case it then resets to "AIR". If turned on and no dive occurs within 2 hours, it will turn off and reset. I have had a similar experience to that of the OP, so you can't set your EAN% too far before the actual start of the dive.

Mike

 

[Steve_C]

I dive both an Aeris and a Zoop,

With the Aeris I have learned to wait until 15 minutes before splash to set the mix. Otherwise it may revert to air. With the Aeris you just go to the percent and then move on. Aeris holds the percent for the next dive if during same day.

With the Zoop I also wait until close to the dive to set it. However, going to the mix per cent is not enough. I have to push the ok button for the setting to take. As I was reminded at 100 ft on fossil ledge when I was wondering where 10 minutes of NDL went. Zoop also holds the percent for the next dive in two dive series.

I am always diving the same mix in both tanks on a given day so I like it that way.