Thanks for your post...

Do you have a multimeter? See if you're getting power at the radio,
don't
just assume it. Next, meter the boat's speaker wires to make sure
they're
o.k.

I'm going out to get one after work today So far I have used the
depth finder to make sure the wire is hot. The depth finder comes on
when I run it off of the same wire... but I guess that doesn't tell me
anything... or does it?

Also, try leaving the yellow wire disconnected when hooking up the red
and
black wires, then tie the yellow to +12v AFTER you've hooked up main
power.

I have tried this...