Thanks for the help. I looked at that link, and cannot locate anything other than vague general references to depth sounders/finders/whatevers.
I'm pretty sure it's a depth/temperature "instrument" of some kind, but it could be a depth charger...I don't know, I thought that was something else but I'm new to this boat stuff.
It has depth, water and air temperatures on its display.
There is another component, (transducer?) in the bilge, just in front of the engine. I think it says AIRMON on it.
This round display mounted on the dash turns on or off by flipping the ACCESSORY switch on the dash.
The temperature function seems to work, though how accurately I don't yet know.
The depth display seems to be random at best.
The main thing is that I cannot figure out how to access a menu on the display. If there is one.
Not being able to locate a manual for this, I looked at many other manuals linked here and elsewhere, and I perhaps wrongly assumed that they all had adjustment capability for setting alarms.
Of course it's possible this one doesn't.
There are two little buttons with:
1 SEL 2
2 EXIT 1
and the labeling on them makes no sense and is not intuitive to me.
Thanks for your help.