Necessity of a back up computer/watch for NDL diving

[Fathom044]

Depends on the dive.

 

[tbone1004]

I typically just wear a watch, but my NDL diving is usually only while teaching and I wear a watch all the time anyway. If I'm doing shore based drift diving, I won't bother wearing a second one. Liveaboard? I'd bring a backup. I have them, I just usually don't bother taking them on benign dives.

 

[rhwestfall]

I could check all three boxes....

It is a "risk/reward" evaluation you should take under consideration. As @tbone1004 said above, what could be the result of an issue? What are the dives you are doing? What does missing a dive (or day) mean to you? Can you safely continue with other methods?

There is no universally "correct" answer.

YMMV

 

[Barnaby'sDad]

I currently have a watch for a back-up. If money was no object, I'd have a back-up dive computer, but I'm just not there yet.

 

[BikerBecca]

I dive with two computers. I guess the pilot in me likes the redundancy.
I dive with a D6i with a transmitter, and a Zoop attached to my SPG. That gives me redundant computers and an analog and digital SPG.

 

[scubadada]

Hi @Divectionist

See How do you dive? 39% of respondents stated they dive a backup computer.

Personally, I dived a hosed AI computer for 4 years, a hosed AI computer and a non-AI computer backup for 4 years, and, for the last 9 years, a primary wireless AI computer with a non-AI computer and a SPG as backup. Of 1,278 dives on my current setup, I have used any backup on 11 dives, 0.9%. Six of these dives were due to my own carelessness, the other 5 were due to equipment failure. I allowed my primary computer battery to go dead and dived the backup computer and SPG for 2 dives. My transmitter battery went dead and I dived the SPG for 2 dives. I forgot to move the transmitter to a different regulator set and dived the SPG for 2 dives. I dived the SPG on 5 dives during an episode of transmitter failure, requiring replacement.

I've dived my current setup for so long that it is simply second nature to me. In addition to backup, I use the SPG to check cylinder pressures when using rental tanks. At a glance, I get some complimentary information from by backup computer to that on my primary computer.

 

[Diver0001]

I am currently trying to decide whether I should wear a back up in the form of a second dive computer (full redundancy as I need an AI feature) or watch (limited redundancy as I don't have an SPG) for rec diving strictly within NDL and am wondering what other SB members are doing and what their rationale is.

At the moment, I lean towards the conclusion that a backup device being unnecessary because in the event of a total dive computer failure or prolonged loss of AI signal, I would generally be aware of my air and NDL remaining, with the ability to shoot my DSMB up as an ascend line even in the event of buddy separation, with a little knot tied into the line at safety stop depth that would allow me to count 3 minutes in my head whilst remaining at the target depth. Should I lose my DSMB, the old slow conservative bubble guided direct ascend to the surface, with an optionally guessed safety stop in the shallows is still a backup-backup solution. The other point is that my dive computer would have to fail many times over for a second device and the hassle that comes with it to be practically and financially justified versus missing one or two dives of the day, which is fairly unlikely.

I'd like to know how you feel about the issue, whether your backup device has proven useful in the past (remember, let's assume no deco/overhead/solo diving for this scenario), whether you wear a dive watch out of old habit, or whether you put up with a second computer, just in case?

For a single dive or dives on one day I never bother. If the computer fails you end the dive and go home. On a dive vacation like a liveaboard, however, I always do because it involves a lot of repetitive dives over the course of a week or so and it would suck to have a computer fail and then need to sit out 24 hours and make the remainder of the dives on tables.

R..

 

[JohnnyC]

For the people who dive a watch, I'm curious how many of you do a time hack before you splash? If you have a dive watch, do you set the bezel? How many of you actually use a dive watch as intended, and how many of you just have a watch with you?

 

[Steelyeyes]

I dive two computers because most of my diving is at places I have flown a ways to get to. I had a computer failure during a dive part way through a week on Cayman Brac. Luckily I was borrowing another one from the owner of our LDS to compare with it on that dive. I was also lucky enough to be able to borrow it for the remainder of the week's diving. Having a second device is just cheap insurance. When I move to a tropical island to live in 34 months or so I'll probably leave the backup computer at home. I still have an SPG so I can leisurely terminate the dive case of an in water computer failure.

 

[Seaweed Doc]

For the people who dive a watch, I'm curious how many of you do a time hack before you splash? If you have a dive watch, do you set the bezel? How many of you actually use a dive watch as intended, and how many of you just have a watch with you?

I have a cheap digital watch that's survived depths to 140'. I start the stopwatch function on descent.