Backup/primary computer questions

In searching for info on a new computer, I have developed a severe case of confusion.

My AI EON is no longer AI so it's useless (bad sensor or something). I fell in love with the Sherwood Wisdom which gets good reviews here. My husband does not like an AI computer and thinks I should go non-AI. Last time I got low on air was, well, the third dive on one tank I THINK. Maybe not even then. But I digress. If I get the Wisdom, should he get something compatible? (his ancient computer is likely to go any time soon)

Likewise, neither of us dives with a backup computer but think we should start. I'd like to get a relatively inexpensive one like an Aeris Atmos 1 to stick in a pocket. But some of the discussion on the boards suggest we should stick with the same computer as primary (well, ya can't dive two AIs, now can ya) or at least something similar.

Any thoughts?

Thanks
Robin

I dive with 2 computers, 1 AI and one is not. Different brands as well. I follow the most conservative of the two computers.

Also, I have an analog air guage (SPG). So, as you can see, I am backed up all the way. If you choose not to go with another AI computer, that's fine. However, please do not go in the water without a pressure guage.

Quarrior:

However, please do not go in the water without a pressure guage.

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Well, thanks to surgery, hurricanes and work, I can't seem to dive anyway and I try to not publicly comment on stupid things I've done diving... But I will be back in the water soon, I hope, and wouldn't mind having stuff that works!

Robin

I forgot to mention the part about each of you having 1 computer. I would suggest you each have a different computer thus you have the ability to dive the most conservative one.

My computers are both wrist mounted, but that is a personal choice.

RobinG:

Well, thanks to surgery, hurricanes and work, I can't seem to dive anyway and I try to not publicly comment on stupid things I've done diving... But I will be back in the water soon, I hope, and wouldn't mind having stuff that works!

Robin

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Quarrior:

I forgot to mention the part about each of you having 1 computer. I would suggest you each have a different computer thus you have the ability to dive the most conservative one.

My computers are both wrist mounted, but that is a personal choice.

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No wrist mount for me. I would get it caught trying to get into the BC--I've gone that route and don't care for wrist stuff. But I thought the rule was to not dive your buddy's computer anyhow...

Robin

I don't think diving with a different computer than your buddy's computer offers any advantage. Computers do differ slightly but the differences do not really matter as long as you dive what ever computer you own conservatively, use sloe ascent rates, saftey stops etc. Having the same computer as your buddy is actually nice as it gives you a better idea where they are regarding deco status on deeper/longer dives.

I also see no need for a backup for recreational diving. In terms of the SPG function of an air integrated computer, if you are monitoring your air supply properly, you will still know roughly how much air you have left even if the the computer totally dies as you would have checked it in the last few minutes. If you don't check your air often enough, a backup SPG will do you no good anyway.

I have used a backup computer from time to time, usually when I get a new one, but I usually discontinue the practice shortly once I am familiar with the new computer as it does not offer any real advantage. N2 loading is a lot like air consumption. If you are maintaining adequate awareness, you will have a good idea where you stand if your computer suddenly dies. Plus with proper predive planning, you are going to know your limits for a given depth and bottom time anyway and you are going to know that you are within them. On a deep dive and on deco dives, I develop a worst case contingency plan for deco anyway. If worst comes to worst, my computer dies, and I am clueless where I am at in terms of NDL/deco status, I can still follow the contingency plan for ascent.

So in my opinion, the best backup for a dive computer is not another computer but rather a dive watch and a simple depth gauge. Capillary depth gauges are inexpensive and quite thin and work much better than a more traditional depth gauge when strapped to a wrist. But they can also attached to a lanyard and tucked into a pocket for use in case you need it. They are a little harder to read at depth as the numbers get closer together. But they are extremely accurate and easy to read above 30 ft. where the final deco and saftey stops occur and where more precision is required. They make ideal backups.

Given the price of basic computers today, I think a backup computer is a good idea. It is a must for liveaboard diving, where you never completely desaturate. Having a computer die in that situation would cause you to lose a day of diving (assuming you wanted to be conservative). Of course, that would be the day the whale sharks did a ballet under the boat

i think that if you AI computer and it dies you should have looked at your air in the last min or 2 and dont need a back-up. i have a suunto cobra and a suunto dive watch so I could make an asent with deco and safety stop safely.

jakubson:

Of course, that would be the day the whale sharks did a ballet under the boat

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We already are responsible for the Chambers of Commerce of many a Mosquito-Infested Paradise changing their motto to: you should have been here LAST week!

Robin

So in my opinion, the best backup for a dive computer is not another computer but rather a dive watch and a simple depth gauge. Capillary depth gauges are inexpensive and quite thin and work much better than a more traditional depth gauge when strapped to a wrist.

Check out the Timex Helix dive watch $40 on Campmor.com. 'Auto water activated, showing temp, depth, & dive time ('can recall after the dive showing max depth & time).