Why are two different DSAT-based computers providing different NDL times?

[divedrewsf]

Hello - sorry to bring up a discussion about such 'old' gear. It is what I use (and have been since 1993/>5000 dives) and it has worked great for me/my diving profile.

The setup:
I just bought two barely-used Oceanic Veo wrist-mounts (180NX & 100NX). Both are fully-operational after diving them.
On my console, I use an Aeris Atmos2 that I've used on > 500 dives now.

All three use the *exact* same algorithm. I am almost certain all three were made by Pelagic during their heyday. Again, all three show the exact same specs for algorithm (DSAT).

On a recent liveaboard trip, I used the 'new' Oceanics for the first time. I was diving air the entire week (Nx was not offered). Right away, I noticed a difference in what my DTR was reading between the Atmos2 and the Oceanics. A couple of times the Oceanics even went into deco (when the Atmos wasn't even close).

I'd like to hear anyone's *experienced/researched* feedback on just wtf is going on here? Because I have used other wrist computers - with the exact same specs - before and they matched up perfectly (although NOT Oceanic- Genesis React Pro, Aeris XR1/2, etc).

Thanks in advance.

 

[divinh]

Were they all set to the same conservatism level? Or maybe the conservatism level is different between brands? Also, to eliminate depth differences, were they all usually at the same depth, versus arm depth and hanging by hip depth?

 

[divedrewsf]

these are fixed systems.....no conservative settings.

again, would appreciate experienced/researched replies. i'm not a newb and have already eliminated differences of placement, etc. Not only would that be 100% nominal in measure, but I've also stated previous experience with similar Pelagic-built models. Net net....that is not what's happening here.

either there is something wrong with the sensors (odd, that both Oceanics would react the same way then) or Oceanic has added some (limiting) code on top of the Pelagic layer (which I have no idea how they would do that...nor why).

Hoping there may be something I missed researching this that someone (in the industry?) may know.

 

[tursiops]

I suggest you use plan mode and compare the NDLs on the three computers. That removes all other confounding variables.

 

[divedrewsf]

I suggest you use plan mode and compare the NDLs on the three computers. That removes all other confounding variables.

very good idea!

but alas, the NDL plan times are *exactly* the same (compared the Oceanic to, both, the Atmos2 & React Pro). the annoying mystery continues.

 

[Alaskan Scuba Dude]

It's a quality control issue. Go with the conservative value.

 

[Raphus]

In such old systems the pressure sensor might not be that accurate anymore..

A small difference though the whole dive might lead to very different ndls

 

[lowwall]

I had a Veo 100NX that failed by showing increasingly shorter NDL times. The dive planner was not affected once the previous dive had cleared (basically by the next day).

 

[Jens Bölte]

Hello,

do the computers show the same depth, more or less? If not, this could result in different DTR.

Best wishes Jens

 

[Jens Bölte]

Hello,

another thing comes to my mind. Did disabled deep stops and the Oceanic computers? This adds two minutes to the DTR whenever you dive deeper than 24 m (80 ft).

Best wishes Jens