Thanks DrMilton. I did understand Pisces answer, although I didn't quite understand what else Sonar732 was trying to tell me beyond what I'd read in the manual.
I guess I was hoping that maybe being a noob, I'd just failed to employ some standard proecedure that all the vets here would already know to do every time you take your boat out. But it doesn't sound like I'll find that obvious an answer. More like I just ran into a tough break by not expecting the mines where I found them ... although I know my C.O. would not accept that as an excuse
... nor do I.
Whatever the reason, I failed ... period. Like you said ... life is tough ...
Thanks again for your tips, folks.