Computer shutdown

[Jim-SAR]

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 ----------




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

I know on my Atmos AI that after a dive, it displays the "No Fly" time for 24 hours, and the computer cannot be shut off. I learned this when leaving Cancun on my first vacation while at the airport wondering if I was going to trash an $800 computer by boarding the plane. Everything was fine, but that was 10 years ago, and I was a brand new diver that didn't know what I didn't know.


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[Unbent]

Ok my computers never got to a ndl, as a multi leval dive, "wreck" was being done, and I never questioned my o2 sat, or nitrogen loading. I nearly said I need to pay ATT to o2 settings if the computers shut down again. I already knew my limits, but if you square profile, I was 1 min over as to the diver in distress. I just stated a fact that if your computer shuts down before a dive as mine did, recheck o2 before diving. I thought this was lessons learned not beat on the willing to share.

 

[doctormike]

I thought this was lessons learned not beat on the willing to share.

Sorry to beat on you with our irrelevant comments.

Thanks for sharing!

 

[flots 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.

All the Uwatecs shut off after a few minutes if you're not underwater and not breathing off it.

 

[DevonDiver]

Lessons to be learned from the OP's report:

1) Read your computer manual. Many models of dive computer retain some default action that retains safety when using nitrox over multiple dives. Some default to air mode, others default to a 'worse case' scenario - recording nitrogen uptake as per air and oxygen PPO2 as per 50=100%.

2) Include your computer in pre-dive/buddy checks. The dive computer is essential safety equipment - as it preserves you from risk of DCI (and O2 tox if using nitrox). Computer users should make a check of computer function and settings a DEFAULT formal component within their buddy/pre-dive checks.

3) Be aware of ALL your computer information when diving. Dive computers typically display (or allow access to) more information than just depth, time and NDL during the dive. Be aware and utilize this information during your dive. For instance, your PPO2, selected mix etc. This would help resolve any pre-dive mistakes - as any user glitches should be quite evident from the information supplied.

4) Understand the relationship between computers and tables. Your computer is very likely to be using a completely different algorithm to that used to form set tables. This makes them completely incompatible for cross-referencing or redundancy. There are numerous mathematical models used to 'shape' dive planning outputs, which take into account different priorities and factors. Read Mark Powell's "Deco for Divers' to gain a better appreciation of decompression principles.

5) Understand how a computer 'credits' you for multi-level profiles. Unlike 'square profile' tables which assume the entire dive at the deepest depth, a dive computer calculates your nitrogen uptake in 'real-time' for the actual time at actual depth. This makes it possible to do considerably longer dives, if you progressively reduce depth over the course of the dive. It does reduce conservatism though.

 

[clownfishsydney]

flots am, Uwatecs do not shut down ever. They are always running. What they do is shut down the screen to conserve power.

 

[Tigerman]

And thats why my aladin prime eats batteries now.. (and why it got replaced)

 

[flots am]

flots am, Uwatecs do not shut down ever. They are always running. What they do is shut down the screen to conserve power.

If yours doesn't shut down, it's broken.

The only thing that continues running is the time of day, and the check to see if it's underwater or a button has been pressed.

 

[Jim-SAR]

Yesterday I was doing some full face mask training with the dive team, and after we finished, and I got home, I put my gear in the garage to dry out.

21 hours later, my Aeris Atmos-AI is still on, displaying a no-fly time of 2h55m. The screen never shuts off until the no-fly time expires.

Re-readin the OP's first post, I see that his shut off between dive site #1 and #2, because he never entered the water at site #1. That makes sense. I'm not sure why the FO2 changed back to Air.


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[fozzy]

Resuscitating an old thread for some info about computers i haven't seen cited, the MARES NEMO and MARES NEMO WIDE computers (probably other Mares computers too) keep the last set dive mode (EAN or AIR) but they also show up if you set them to "pre dive". In dive mode the CNS value showing *SHOULD* be warning enough...
They shut down the screen autmatically after the DES and NOFLY counters expire. (but you can turn the display off earlier).
Batteries last at least a couple of years with 20-25 dives a year...