Nitek HE Dive Computer Question

[TracyN]

Hey all, I was wondering if anyone familiar with the Dive Rite Nitek HE computer might be able to help me. Before anyone asks I scoured through my owner's manual to try to find the answer to my own question without success. I have gone on many deco dives with this computer and have never seen this happen before. At first I thought it might have been due to a low battery but that was not the case. I had a Dive Rite Nitek Duo as my backup computer. This is what happened. We were doing a three tank shark dive so the depths were moderately deep.

First Dive:

Nitek HE: Max depth 118/Avg depth 82, Dive Time: 30 min

Nitek Duo: Max depth 130/Avg depth 91, Dive Time: 30 min

Surface Interval: 00:01:15

Second Dive:

Nitek HE: Max depth 126/Avg depth 80, Dive Time: 52 min

Nitek Duo: Max depth 138/ Avg depth 61, Dive Time: 52 min

Surface Interval: 00:00:46

Third Dive:

Nitek HE: Max depth 72/Avg depth 42, Dive Time: 41 min

Nitek Duo: Max depth 75/Avg depth 42, Dive Time 41 min

The first dive I ended up with 6 min of deco, the second dive I ended up with 10 min of deco but on the third dive my Nitek He went crazy and by the time I surfaced it said I had a 76 min deco obligation! The shallower I got the more deco it accumulated. Started out with 10 then went to 30 then 40 and then 76. Something was obviously wrong because my Duo wasn't giving me any deco. I called the dive because of this discrepancy and of course I went by the Duo's deco schedule. The only other thing I can think of is that the HE didn't like the surface interavals? I'm also trying to figure out the discrepancies in depth between the two computers. Any insight would be greatly appreciated.

 

[wmperry]

Could the HE have given you a ceiling that you violated and it got progressively more pissed off about? But with the 12' depth discrepancy the duo did not impose the ceiling so it stayed happy?

Not familiar with the Nitek so not sure how obvious ceiling restrictions are in the UI or if it even calculates that way.

 

[TracyN]

I don't believe the HE calculates with ceiling restrictions. What I noticed today is that the computer automatically jumps to the next conservative level for repetitive dives and the Duo doesn't do that. I'm sure the short surface intervals are what caused my computer to throw it's little temper tantrum.

 

[MXGratefulDiver]

I had a HE for a while ... hated the damn thing. I bent it every single time I took it diving. It seems as though the computer wants you to do ALL of your deco above 30 feet, regardless of profile or type of gas you're breathing. After a dozen dives or so I found somebody who likes to dive that way and gave him a really good price on a trimix computer ...

... Bob (Grateful Diver)

 

[TracyN]

That explains it Bob. It gives me no credit for anything below 30 which would explain why I always seem to get much more deco than my buddies. That's why it remained tied to a reel doing deco all by it's lonesome Thursday at Peacock.