GEO 2 Alarm question

[Aloha Joe]

This has happened to me a few times now, and on last night’s dive happened to me and a guy I was diving with who had the same computer: it looks like the tissue loading bar graph (TLBG) alarm is going off, but the computer said I have tons of NDL time remaining.

Last night I was diving 33% nitrox on my first dive of the day (first dive in a week). PO2 level set to 1.4, algorythm on PZ+ with no conservative factor (buddy was on DSAT). TLBG alarm set to 4 (5=deco condition), depth alarm set to 110ft.

Buddy and I were hovering around 80ft and both our alarms were going off. GEO 2 said I had ~20min dive time remaining at the time, he said his was the same when we talked after the dive. The manual says Geo 2 monitors no-deco time and O2 accumulation, and displays time remaining for whichever is the limiting factor.

Recorded data: Max depth = 86ft, total dive time 36min, TLBG = 4, O2 sat=14, P02 = 1.31.

Why would TLBG alarm go off, and show I’m at the limit of decompression, yet the computer show 20 minutes of dive time remaining? Or is it something else?

I’ll email Oceanic as well, I just thought this might lead to more discussion.

Thanks!

 

[RTC'83]

Following

 

[Aloha Joe]

Here’s what I think it is:

The P02 ‘setting’ is under the Alarm menu, so ‘setting’ 1.40 is just for the alarm. The Geo 2 gives a ‘WARNING’ at 0.20 less than the alarm setting, which in this case would be at 1.20. Supposedly there’s another alarm when you get to whatever number you set. The P02 alarm/warning happens as a function of depth, not dive time or dive time remaining, which is why the computer shows plenty of dive time remaining and still gives this ‘warning’.

I think it’s kind of a stupid feature - I can set an alarm for whatever P02 I want, and can set an alarm for max depth. I don’t know why I need to get an early ‘warning’ - which if very much is - beeping, flashing red light, change in display, etc. It would be nice if you could turn off or change the warning but I don’t see a way to do that, at least in my firmware.

 

[scrane]

Alarm is programable to go off at variable tlbg steps. How is your alarm programed?

 

[Aloha Joe]

Tlbg alarm is at highest setting (4). It’s the PO2 warning, it went off again at beginning of dive yesterday, same dive site. The screen changes for P02 warning.

That said, I do want to pay more attention to TLBG vs NDL/DTR since it seems like the TLBG loads up quick with still lots of DTR.

Although, I just got a new computer so we’ll see how much more attention the Geo gets.

 

[Aloha Joe]

Now I have another PDC I can try turning off the TLBG alarm and see what happens.