Redundant Dive Computer

[Minion_Diver]

When diving with a redundant computer, do you dive with the exact one as your primary or is your secondary a different make and/or model?

I dive with a redundant computer and it is my old computer. I normally keep it set on basic dive mode as I am not doing real deep or technical dives right now.

 

[rongoodman]

Ideally the will both run the same deco model even if they're not the same computer. Otherwise, they're not really backing each other up,

 

[outofofficebrb]

The backup does not need to have the same exact algorithm or be the same model. So long as the backup is using a same or more liberal algorithm than your primary, it is fine. Don't use a more conservative computer than your primary to use as a backup computer.

For example, I would not have a RGBM (Suunto) algorithm be my backup to a DSAT or Buhlman computer, but it is OK for a DSAT or Buhlman be a backup to a RGBM (Suunto). If I used RGBM (even on most liberal setting) to backup my DSAT or Buhlman, it would likely lock out and that would defeat the purpose of a backup.

I hope that makes sense.

 

[scubadada]

If they don't match, the more conservative will control your dive and you will have to dive it, or satisfy its deco obligation, to avoid being locked out for subsequent dives.

 

[Nomad-Diver]

They used to be two different brands, but are now the same brand. The key for me is to set the backup one with a less conservative setting. If i need to get out of the water asap, it's nice to know the bare minimum (should I choose to take that route).
If, heaven forbid, my primary computer fails then I'd just add time to each stop to add the conservatism back in

 

[Snoweman]

I use my Zoop as a backup because I'm not spending another $1,000 for a second Perdix.

When I dive air, I set my Zoop to 21% Nitrox. I was told it was a way to make it a little more liberal. I haven't gotten into a deco with it since I switched it to the nitrox setting.

 

[outofofficebrb]

I use my Zoop as a backup because I'm not spending another $1,000 for a second Perdix.

When I dive air, I set my Zoop to 21% Nitrox. I was told it was a way to make it a little more liberal. I haven't gotten into a deco with it since I switched it to the nitrox setting.

Interesting. I used to dive with a Suunto primary and backup. My partner always has and still continues to do so. After a certain number of back to back dives over a week's time (4-5 a day), the NDL started catching up with him on his Suunto even on the most liberal setting and while I was only on medium for my Perdix. Call me stupid for asking this, but I don't see how setting it to 21% nitrox vs air really changes how liberal or conservative the computer will be...Bueller? Anyone care to explain this one to me?

Thanks.

 

[Snoweman]

Interesting. I used to dive with a Suunto primary and backup. My partner always has and still continues to do so. After a certain number of back to back dives over a week's time (4-5 a day), the NDL started catching up with him on his Suunto even on the most liberal setting and while I was only on medium for my Perdix. Call me stupid for asking this, but I don't see how setting it to 21% nitrox vs air really changes how liberal or conservative the computer will be...Bueller? Anyone care to explain this one to me?

Thanks.

I was told it's a little glitch in it's algorithms.

 

[Centrals]

I used to dive with two same brand computers(Uwatec Aladin). And when one of them died, I bought an Oceanic which is a more liberal so used it as back up.

 

[TrimixToo]

Two computers, one Petrel, one Perdix.

Perdix set fairly conservatively, Petrel much less so. The Petrel is the "get me out of the water without getting hurt too bad" computer, and the Perdix* is the one that controls the dive, unless it ever fails. If it does ever fail, the Petrel allows me to change the GF high to be more conservative underwater so I can continue the ascent as usual.

* Corrected, thanks to tridacna.