Backup Wrist Computer

[suzbo]

Maybe I'm overthinking this.


I'm looking to buy a backup computer, wrist style. I am strictly a vacation, recreational diver. I simply like the idea of having a second computer that goes with me on my dives, in case of some failure of my primary during a dive (or during a trip). (If that were to happen, I'd continue to use my SPG and compass on my console, or rent one from the shop where I was diving, if they had failed as well. So I'm not looking for those features on a backup.) I don't need lots of bells and whistles, and there are a number of models that I think would be great for me.


My question is this: what is everyone's thinking on the need for your backup computer being the same as your primary? Exact brand? Just similar algorithm? What about having a backup that uses a different algorithm from your primary? Do people feel this is an absolute no-no, or is it the perfect approach?


Discuss.

 

[CaboJim]

I bought a used Scubapro Xtender for $225 on Ebay. My main computer is the galileo sol. the algorithum is similar, on the Xtender, but a bit more conservative. I keep a spg in my bag for the Xtender...
For a back up, shop around, you don't have to buy a new one....

 

[Jerry_]

Taking into account that you are a recreational diver diving in vacation only, I would suggest you to have a backup (provided you want to make the investment) which is very similar to your main for the following reasons:

(1) avoid misreadings. the displays and functions will vary by model and brand (avoid getting puzzled f.i. to mix the readings of duration and depth, know which button does what)

(2) should not be a matter of price. considering your type of dives you should be able to go for the simpler/less expensive models (also your backup could be a second hand)

(3) have your computers providing identical deco stop information. having different computers, one can be more restrictive than another even if algorythms are very close (meaning that the backup may go in blocked/alert mode when you exit the water while your "main" said that it is fine.), i.e. Having a backup means respecting the most restrictive of the stops imposed by either of the two computers. This can be triggered by duration/depth/surface interval and has some impacts on NDL & safety/deco stops.

 

[Pavao]

I have a back up with me always, out of town trips, or simply a local day outing, I have it on my bag/spares though, I don't carry it on the dive with me, with recreational limits you would be pretty safe, specially staying with your buddy always (right ).
My opinion is that having a spare is more to do with convenience and piece of mind of knowing you're prepared and won't have to skip a dive or spend more than you'd need to because of last minute surprises.

BTW, I know someone selling a cheap ($100) used wrist computer

 

[diversteve]

It's not a wrist mount but you might consider the Oceanic B.U.D. since:

This new Dive Computer is a must for every diver to carry because no matter what computers you are using, you will be able to set your B.U.D. to closely match any computers profile using the Oceanic Patented DUAL ALGORITHM.

Also it's $200 new. B.U.D. - Computers

 

[suzbo]

Yeah, I originally thought the B.U.D. was just what I wanted. Then I realized their "dual algorithm" is their own patented thing. And while you can set it liberal, conservative, or somewhere in between, it does not, in fact, have RGBM - what Suunto and Mares use. (And my primary is a Suunto.). What they have is DSAT and Z+. This is, in fact, what sent me off on my questioning whether it matters, or if so, how much? Should I get another Suunto which would exactly match, a Mares, which uses RGBM but I understand is not exactly the same as Suunto's version; or does it really even matter, and it would either be ok, or actually preferable, to have my backup use a different algorithm.

As as I said, I may be overthinking this!

 

[Agility]

If the backup is only used to track your nitrogen loading as not to lose out ona dive if the primary computer fails, the algorithm is not quite as important, you should make sure though that is (as or) less conservative than your primary so that it is not locked by ignoring deco the primary might not mandate.
I always dived my Oceanic Veo 2.0 in DSAT mode but changed it to Z+ (ZHL-16) since i use it as backup for my Predator (running on GF 30/70)

 

[Lorenzoid]

Yeah, I originally thought the B.U.D. was just what I wanted. Then I realized their "dual algorithm" is their own patented thing. And while you can set it liberal, conservative, or somewhere in between, it does not, in fact, have RGBM - what Suunto and Mares use. (And my primary is a Suunto.). What they have is DSAT and Z+. This is, in fact, what sent me off on my questioning whether it matters, or if so, how much? Should I get another Suunto which would exactly match, a Mares, which uses RGBM but I understand is not exactly the same as Suunto's version; or does it really even matter, and it would either be ok, or actually preferable, to have my backup use a different algorithm.

As as I said, I may be overthinking this!

I use a Suunto Zoop to backup my Suunto D6 and my wife's Suunto Cobra. The logic of having identical algorithms was persuasive to me. I have found the two computers will read within +/- 1 minute of each other. Pretty good.

 

[gurnie]

I am all about redundancy even while conducting recreational dives. I have had couple of instances where having a backup computer meant that I could continue to dive rather than calling off diving during a trip. If you can get the same algorithm that is great, otherwise if your backup is less conservative you should be fine. The only reason I say less conservative is that you don't want it to lock you out for a violation. I thought the B.U.D was a great idea, but I have an extra zeagle n2iton that I tuck away in my BC. Computers flood, batteries die, consoles get crushed by tanks why not be prepared for it..

 

[Steve_C]

I dive an Aeris (less conservative) and a zoop (conservative)

I usually treat the zoop as primary but under certain circumstances will base my bottom time on the Aeris. I clear both computers before leaving the water. Personally I like having two different NDL numbers knowing one is conservative and the other is more liberal.

I am strictly a recreational diver but that can include some 80-100 ft dives and sometimes a tad deeper than 100. The deeper dives are always NDL limited and not Air. I would never dive a computer that locked me out for anything other than surfacing having skipped deco. If that ever happens (and it has not happened yet) I should not dive again that day anyway. If for some reason you find yourself a tad over the NDL you want a computer that will safely get you home.

Stuff happens. Buddy has an equipment or other issues that takes a few minutes to resolve. You have plenty of air. Your choices are an open water ascent from 100 ft into current or doing a 10 minute stop on the anchor line. Safest option is the anchor line.