Dead computer - No backup

[Tigerman]

Im not sure if this is the place to post this as it was really more a "learning experience" mostly triggered on purpose.

Background (if you skip this part you might make comments Im already aware of):
This whole experience began when I for some reason had my computer in the car and as the temprature dropped it started warning me about a low battery.
I decided to use this for an experiment of sorts.
How lost would I feel if I have no backup and my computer dies? How would it affect me to lose track of my depth and dive time?
Since its still fairly cold water here (approx. 13c/55f) and I need to replace that battery anyways (which I did today), I decided that this is an opportunity to "simulate a dead computer". I chose a known site with black muddy bottomn, virtually no entanglement hazard (theres always the chance of a freak accident), no currents and easy bottom conditions gradually going deeper as you go away from shore, but also very even depth if going along the shore.

Execution:
About 4 minutes into the dive the computer start warning me about low battery at approx 20 feet. 6 minutes into the dive im at 27 feet. I tend to check my gauges about every minute or two unless im descending/ascending. I decided to swim along the shore and just maintain depth and see if I could see more of the bass and trout I saw on my way out.
Next time I check the gauges after approx 8 minutes total dive time I score. The computer is now showing nothing but an icon indicating the computer needs service.

Heading back to shore and going gradually shallower I can feel that I ascend slowly as the water get shallower. However, out of instinct I reach for my computer to check how deep down I am, with nothing but a wrench showing on the display.
Obviously air is not an issue, nitrogen loading is not an issue, narcosis is not an issue. In short theres actually absolutely no issue what so ever except the lack of knowing my depth and dive time. As Im starting to get real curious/unsure about how deep I actually am and realizing that this situation would suck BIGTIME if I wherent on a shallow dive with virtually unlimited NDL, I decided its time to follow the plan and surface slowly. I dont think Ive ever surfaced that slowly before, barely noticing im going up.

Conclusion:
What my conclusion was? I dont want to be left out there without a depth gauge and a timer for sure. If this was a technical dive (which I dont do.. yet) this situation would pose an enormous issue. Even on a rec deep dive, this situation could potentially bring up serious issues. Not knowing your time and depth could put you into a deco obligation that youre not even aware of for one.

Disclaimer:
I do not encourage or suggest anyone to test this themselves.
I know quite well that this dive had an elevated level of risk. It was planned knowing it had additional risks and performed constanly considering and taking precautions according to that elevated risk factor. If you want to tell me about how stupid this dive was, know that Im aware that it was a far from ideal dive from the moment I first thought about doing it..

 

[Charlie99]

Thanks for a thought provoking post.

Just like any other piece of equipment, you need to be able to deal with the failure of a computer.

People lucky enough to dive in reasonably clear water should be able to easily execute a controlled ascent.

People diving with a buddy have his gauges as a backup.

A solo diver in low enough viz that they can't determine depth need to have an alternate plan, even if it is as crude as knowing the right heading to follow the bottom contour back up to the shore/surface. Another option could be a DSMB to give a tactile reference.

I DO encourage divers to do drills on how they will handle gear malfuntions such as reg failure, computer/bottom timer failure, lost or leaking mask, and loss of buoyancy bladder in BCD or BP wing. It's best that the surprises come during a controlled drill.

 

[CoralSeaMan]

This scenario always haunts me as I use an integrated computer without an integrated backup. I do have a non-integrated computer as a backup. I don't know how much air I have but I can keep track of ascent, depth, and general nitrogen or O2 load since I must promptly exit the water if the integrated computer goes out.

 

[Charlie99]

This scenario always haunts me as I use an integrated computer without an integrated backup. I do have a non-integrated computer as a backup. I don't know how much air I have but I can keep track of ascent, depth, and general nitrogen or O2 load since I must promptly exit the water if the integrated computer goes out.

Why should the failure of your air-integrated computer or an SPG haunt you?

If you are planning and diving properly, then you always have enough air to safely complete (or at least abort) the dive. Indeed, you should be always be carrying enough air for both you AND your buddy to safely abort the dive.

If this is true, then loss of pressure info should be no big deal. Just end the dive gracefully.

 

[ianr33]

A solo diver in low enough viz that they can't determine depth need to have an alternate plan, even if it is as crude as knowing the right heading to follow the bottom contour back up to the shore/surface. Another option could be a DSMB to give a tactile reference.

I tie knots in the line on my spool. 1 knot at 10 feet,2 at 20 and 3 at 30.

If it all goes to hell on a dive then I would send up a bag,ascend up the line until I feel the 3 knots at 30 feet,count down a minute then continue to ascend slowly.

To actually use this I would need to lose my buddy and have 2 computer failures!

 

[wve]

I tie knots in the line on my spool. 1 knot at 10 feet,2 at 20 and 3 at 30.

Now why haven't I thought of that!

Great idea. As I am packing for a trip next week, I'm heading into my gear room right now to do just that! I'll put one knot at 10 ft, 2 at 20 ft, etc.

 

[TSandM]

There are local sites where the loss of a gauge wouldn't bother me at all, because I'm so familiar with the site, I can tell you fairly precisely what my depth is at any point, and how far it is (in minutes) to shore.

If you pay attention to your gas consumption, you can use that as a crude timer as well. If you are using air integration with a remote sender and your gauge goes down, then you've lost time, depth AND pressure, which is one of the reasons I don't use that kind of gauge.

If my gauge goes down on a dive at an unfamiliar site, I'm going to communicate that to my buddy, and we are going to decide on a plan to cope which depends on the terrain and the limiting parameters of the dive. I have gross tables in my head, which helps.

 

[fppf]

I just carry 2 computers, there cheap all things considered.

 

[ronbeau]

Im not sure if this is the place to post this as it was really more a "learning experience" mostly triggered on purpose.

Background (if you skip this part you might make comments Im already aware of):
This whole experience began when I for some reason had my computer in the car and as the temperature dropped it started warning me about a low battery.
I decided to use this for an experiment of sorts.
How lost would I feel if I have no backup and my computer dies? How would it affect me to lose track of my depth and dive time?
Since its still fairly cold water here (approx. 13c/55f) and I need to replace that battery anyways (which I did today), I decided that this is an opportunity to "simulate a dead computer". I chose a known site with black muddy bottom, virtually no entanglement hazard (theres always the chance of a freak accident), no currents and easy bottom conditions gradually going deeper as you go away from shore, but also very even depth if going along the shore.

Execution:
About 4 minutes into the dive the computer start warning me about low battery at approx 20 feet. 6 minutes into the dive I'm at 27 feet. I tend to check my gauges about every minute or two unless I'm descending/ascending. I decided to swim along the shore and just maintain depth and see if I could see more of the bass and trout I saw on my way out.
Next time I check the gauges after approx 8 minutes total dive time I score. The computer is now showing nothing but an icon indicating the computer needs service.

Heading back to shore and going gradually shallower I can feel that I ascend slowly as the water get shallower. However, out of instinct I reach for my computer to check how deep down I am, with nothing but a wrench showing on the display.
Obviously air is not an issue, nitrogen loading is not an issue, narcosis is not an issue. In short theres actually absolutely no issue what so ever except the lack of knowing my depth and dive time. As Im starting to get real curious/unsure about how deep I actually am and realizing that this situation would suck BIGTIME if I weren't on a shallow dive with virtually unlimited NDL, I decided its time to follow the plan and surface slowly. I don't think Ive ever surfaced that slowly before, barely noticing I'm going up.

Conclusion:
What my conclusion was? I don't want to be left out there without a depth gauge and a timer for sure. If this was a technical dive (which I don't do.. yet) this situation would pose an enormous issue. Even on a rec deep dive, this situation could potentially bring up serious issues. Not knowing your time and depth could put you into a deco obligation that you're not even aware of for one.

Disclaimer:
I do not encourage or suggest anyone to test this themselves.
I know quite well that this dive had an elevated level of risk. It was planned knowing it had additional risks and performed constantly considering and taking precautions according to that elevated risk factor. If you want to tell me about how stupid this dive was, know that Im aware that it was a far from ideal dive from the moment I first thought about doing it..

The simple solution (assuming your dive computer has a user serviceable battery) is to always carry an extra battery with you.

Two years ago in Curacao my daughter's Aeris ATMOS AI indicated low battery during the pre-dive check. We simply dug out a quarter and opened the battery port, replaced the button battery, replaced the battery port and we were all set to go.

Computer failures are extremely rare (excluding low battery which is preventable by having a spare).

Diving conditions where I live are similar to yours but somewhat colder (as cold as low 40^o F).

 

[peterbj7]

Unfortunately many computers don't have user-replaceable batteries. The worst part of my Suunto Stinger is that it has to go back to Suunto (in a different country) every 15-18 months.