Conflicting Vypers

[lmcgill97]

I carry nominally identical Vypers as my primary and backup computers. On a recent dive trip, my primary was perfectly happy, while my backup (which was in a pocket) went into deco and ultimately locked up. The overall situation is:

1) Primary computer never showed deco during any dive (I'm 100% sure of this)
2) Secondary computer went into deco during the fourth dive of the series (and locked out in this case as it thinks I violated a ceiling)
3) Both computer downloads indicate deco in DM

Is there any way to understand why the two Vypers differ and which one is "right"? Also, are the DM logs discrepant just due to sample rate? I don't care as much about the DM log, but having one happy computer and one in Er is concerning. Thanks,
-Lisa

 

[BigJeff]

I see this often as I also dive with two computers (also Suunto).

I'm willing to bet even if you looked at both while holding them at exactly the same depth during a dive they would read the depth slightly differently. This is just due to the measurement tolerances of the sensors.

If you are going close to NDL on a dive, or on a series of dives during the day this difference can mount up to easily a few mins.

I have seen up to 15 mins difference in NDL (at depth) on a long 5 dive day and much more during the safety stop.

The only solution I can offer is to keep an eye on both computers during the dives, and unless one is obviously faulty then dive to the more conservative one.

The one in your pocket should also have alerted you to the violation as you rose above the ceiling height, if it was not beeping constantly then there is a problem with that one.

 

[fmerkel]

There are also a couple tweaks you can do to alter how conservative they are. Make sure they match.

 

[Bob DBF]

I'm willing to bet even if you looked at both while holding them at exactly the same depth during a dive they would read the depth slightly differently. This is just due to the measurement tolerances of the sensors.

Also, depending on the position of the computers on your body, there may be an actual depth difference as well. With the spare in a waist pocket and watching the other you could have a foot or two difference between if you do vertical surfaces and dives, this can add up. Since you are not monitoring the one in your pocket you can't correct your dive for it's information as you would for the one you wear. If I were to use those two computers, I would probably attach one to the tank valve or wear them togather


Bob

 

[DuboisP]

same problem this sunday
1st dive, nothing special in the profile
2nd dive, nothing special in the profile
- buddy computer (Galileo or Nemo Wide), deco erased
- my 1st computer (OSTC MKII), deco erased
- my Suunto Vyper Air, mandatory deco 15 min. goto ERR