Possible thief?

I’m trying to determine if a thief was trying to steal my batteries. I have a private boat dock setting alone on the bank. There are 2 larger gauge wires coming from the motor (1993, 200 hp LRR, Yamaha outboard) The Negative (black) wire was off and hanging down near the batteries, yet all the wing nuts were tight on each battery. Both batteries were stone dead and had to be replaced. What puzzles me is why the wing nuts were tight on the batteries??? I had the wiring worked on by a mechanic last year. The boat ran great until I found the batteries were dead. There was a period of about 3 months of inactivity with the boat. I have an on board Battery Maintainer. What do you think??? If so I probably will install a security device at the dock.

[jb123]

...........corrosion

[TimS]

Are you sure those are your batteries? Maybe someone did a moonlight upgrade - stole your two and put back two dead ones from their own boat.

Tim

That's a thought. I don't know because I turned in the old ones when I bought new batteries. The problem is, when I tried to hook up the other wire from the Motor, the Motor tilted all the way up. It's as though it had shorted out before and was left off on purpose. Anyway at the moment I have nothing. My gauges, tilt & trim, starter, nothing works. I can't find any burnt wiring any where. I do have other smaller wires to the battery but I have not yet tried to ring them out. I guess I'll have to completely re-wire the thing. The tilt & trim worked fine before all this happened.