Backup to a computer?

[Tao of the Dive]

Okay, on a recent visit to my LDS, I inquired with the shop owner if he thought I should have backup guages to go with my dive computer. He afirmed my thoughts, since he has had computers crap out on him at depth, and since then, he dives with a computer and a pressure gauge. My question to all of you is, do you dive with a backup set of gauges or at the very least a pressure gauge? Or do you put all your confidence in your computer?

I'm purchasing a new set of regs, and I figure while setting up my new primary dive rig, I might as well go all out. Your thoughts?

 

[glbirch]

Never hurts to have a backup computer. My primary is a wrist mount and my old Suunto Companion goes in a pocket of my BC. I also have a brass pressure guage that I will probably never give up. I too have had my computer fail in mid-dive and don't need something like that throwing a wooden shoe into my dive holiday.

What kind of regs you going with?

 

[ScubaRon]

For non-deco diving a backup with a gauge does not make much sense. If your computer fails you need to immediately abort the dive and do a safe ascent with a safety stop.

For deco diving a backup is critical (as you need to know your stops), but IMO an SPG plus some dive tables are not going to help you much. In that case I would use a 2nd computer as a backup, preferably of a different brand. keep in mind that you always must carry that backup computer otherwise it won't have the right profiles.

I do strictly non-deco diving and do not carry a backup.
ScubaRon

 

[DA Aquamaster]

I dive independent doubles so there is another SPG along and I normally have a back up computer along. I also have a reel and a lift bag and the line on the reel is marked in 10 ft increments for the range where any deco will occur. So it is an ascent line and also a backup to the backup in terms of determining deco stop depths.

In the pre computer era, I used a capillary depth guage as a backup. It was light, slim, inexpensive and very accurate at depths above 60 feet.

I agree also that it is a moot point if no deco is involved - you just end the dive with an ascent. A saftey stop can be guestimated at 15 ft as 3-5 minutes at anything above 30 feet and below 10 ft will work.

 

[Mark Vlahos]

Hi,

I dive with a Cochran Gemini in a completely redundant system, if you are not familiar with the Gemini the tank unit is the main computer and makes all of the calculations. I use a monitor wrist unit as the display for the tank unit. I also use an intelligent wrist unit (clipped to a d-ring) as a back up to the monitor wrist unit. If the tank unit should fail the intelligent wrist unit will take over all calculations except tank pressure, for that I have an old fashioned SPG. I also carry a small slate with my dive plan written on it.

I have not had this setup very long but with other computers I have had enough glitches to make me uncomfortable with only one set of (timing/depth/tank pressure) measuring devices. Yes if you have a failure you should be able to surface safely, assuming you are within your plan, but I would rather not have to abort either one dive or a day of diving because of an equipment failure

If you plan to dive with two different computers you should plan on making the more conservative one the main computer. Or best yet just check them both often. If one should fail you will not be helped by discovering that the "backup" computer is telling you to make an unplanned deco stop when you are low on air because you exceeded its limits a couple of minutes ago while your other computer said you were still fine.

This kind of situation kind of reminds me about what it was like when I rode a motorcycle... Everybody says you should assume that the cars can not see you. I took the opposite approach, I figured that the cars could see me and that they were actively trying to kill me! Dive computers should not fail but you should expect that one will fail at the worst possible time!

Happy diving,

Mark Vlahos

 

[Warren_L]

I run with a backup Vyper on my console to my Vytec. I'm not so much concerned about my depth and air during a dive so much as being able to continue my day. I generally have a pretty good idea of both air and depth during my dive, so losing this info is not that critical. It's just my NDLs. If the Vytec craps out (so far no problems yet) then just switch to the Vyper. And the Vytec should also never fail due to the battery run out as that is something that I check regularly anyway.

 

[jplacson]

I just stick close to the rest of the group. And I try to stay a bit shallower than the DM... that way I know my profile isn't as aggressive as his, and the safety stop should be fine. These are NDL dives of course, and I just do that as a precaution should my Vytec ever crap out on me during a dive.

 

[ScubaRon]

I just stick close to the rest of the group. And I try to stay a bit shallower than the DM... that way I know my profile isn't as aggressive as his, and the safety stop should be fine.

After your first dive this theory does not apply at all and it is a fact that frequent and strong divers (like divemasters!) have a much higher resistance to DCS. So I strongly suggest you use your Vytec.

 

[jplacson]

That's true... and I do use my Vytec... I only stick to the group, in case the thing craps out on me. And most of my group run Vypers anyway, so it's pretty redundant. We don't puch limits on fun dives anyway.

 

[diver_paula]

I always dive with two computers. Before that I dove with a computer and full set of gauges. If a computer fails I don't want to miss dives later in the day or weekend. & who wants to sit out a full 24 hours when on a week long dive trip? Not me!

Paula