Digital Bottom Timer and altitude

[Wijbrandus]

My buddy and I are going to the local mud puddle Friday for two tanks. This is an altitude dive of 6000 ft. to a max depth of 60 ft. And a nice toasty 68 degree water, above the thermocline.

I haven't used this bottom timer yet at elevation. How does it compensate for altitude? One of it's advertised perks is "Automatic altitude compensation", but does that mean it just measures accurately at altitude and read true depth, or will it read depth that has been compensated for my current altitude?

I'm assuming it just means the device is self-calibrating for altitude, and will read a true and accurate depth that I will have to adjust for my altitude to get a theoretical depth for NDL. Assuming is bad, even though I do have my DAN paid up.

The manual is not specific enough on this, and I haven't recieved a reply from Uwatec on it either.

I am probably overanalyzing this, but hell, I'm still a rookie. I figure in a worst case situation I'll just add depth to the reading per the altitude rules, and if it get's added twice, then I have that much more of a conservative profile.

 

[MechDiver]

I can't remember where the steps are, but the B/T will alter the depth displayed depending on the altitude. IOW, the depth you see will be *true* for that altitude. You will not need to compensate further.

Baring any change to the model, thats how mine work.

 

[Wijbrandus]

I can't remember where the steps are, but the B/T will alter the depth displayed depending on the altitude. IOW, the depth you see will be *true* for that altitude. You will not need to compensate further.

Baring any change to the model, thats how mine work.

Thanks, MechDiver. I'll go over the manual again tonight then and make sure I'm not missing something. The manual stated that this one does so automatically, but I'll make sure there are or aren't any steps involved.

Just for clarification, because I'm an idiot, when you state "*true* for that altitude" that means it is reading the depth as if it is after I look at the altitude tables for nitrogen loading, correct? Sorry if I am coming across as obtuse. I just want to make absolutely sure I'm dealing with it the right way.

For example, with the standard rental console, the depth will read 40ffw. At 6000 ft, when looking at the tables, I need to add 8 ft to that depth when working on the tables. [I made the numbers up.] With the bottom timer, it will read 48 ffw?

You know, this whole thing is probably moot. I'm using a rental reg and it has a brick console on it. I can just compare the freaking numbers and see what happens. I know for a fact the console doesn't compensate for altitude at all.

I wonder how many other divers overthink these questions too. Or maybe I'm just overly anal.

 

[MechDiver]

For example, with the standard rental console, the depth will read 40ffw. At 6000 ft, when looking at the tables, I need to add 8 ft to that depth when working on the tables. [I made the numbers up.] With the bottom timer, it will read 48 ffw?

Yes, you got it.

I wonder how many other divers overthink these questions too. Or maybe I'm just overly anal.

Being anal about safety issues is usually a good thing. That being said, I think the altitude issue is overblown by most people.

MD

 

[Wijbrandus]

Many thanks, MD. I feel better about it already.