Dan, I had to chuckle at your post. I'm a pilot, also ex-Army, and can just see myself cruising like Apache gunship driver with a heads-up display. lol

Heavy,
The whole idea behind depthfinders is to show us that there is something between us and the bottom. True, it could be a log, could be a bass. What's important is-is that there is something there, we're not just fishing a featureless-fishless bottom.
It's okay to not believe in depthfinders, in fact, I wish no one else did. Bet I'd win a lot more tournaments. But; I respect your right to not have faith in them.
The ice depthfinders you quiered about are for ice fishing. Each colored line represents either the bottom, baitfish or fish of some kind, plus bottom cover or structure. By identifying the depth, where the baitfish are and finding some type of cover our chances of catching fish are greatly enhanced.

o cool