Rusty Electrons
They almost resemble the small diameter wires that we have for the masthead 12 volt wiring and the wind transducer, but there are a lot more of 'em in the picture. The other side of the terminal block does not seem to show anything connected to them.
Our masthead wiring comes out of the spar just above the headliner, in any case.
Can you access the other side of the entry point for them, into the bilge?
ID them and pull them out...
Aside from knowing what historical device(s) were connected to them, there is the scary mind-set of whoever thought a bilge was a suitable place for *any* sort of open wiring connection.
Check them one by one with your multimeter and see if ANY of them are hot when any/all breakers are switched on.
Have you found other installation oddities in your boat from a P.O. ??
Gotta say, I've never before seen anything like that.
Good luck!
ps: I sent this thread over to a marine electrician that I know. With many years of experience, even he is puzzled... and he comments:
"I have seen worse in some older power boats, never in a sailboat that I can remember though. It does appear to be a terminal block vs a power block, with only one side of the circuit connected. My guess would be some old instrumentation that has been removed. I'd be surprised if there were any power going to it, the corrosion alone would probably start a fire. "