Well I decided to take care of some repairs on the boat since the high water closed most of the ramps on my local lakes. I had one of my two bilge pumps go out so I cut the wires and put a new one in but no juice.

I figured the wire corroded so I removed the deck (2001 Logic 17' cc) and untangled the wires and cut away
a thousand feet of ten year old electrical tape all the way to the panel on the center console. No joy so I removed the panel and tested the switches, no problem but no power. I sat there staring at the panel for an entire beer when I noticed the switch had a button beneath it that I had never really looked at before. I pressed the button and it clicked and the bilge pump started working. Apparently it was a micro circuit breaker that had popped because of the bad pump.

Well, great! I put the panel back on and retaped the wiring and put the deck back on (on a Logic it is one pure PITA) and remounted the seat on the deck and reattached the battery cables and the bilge pumps both worked but the horn wouldn't.

So the next day I get home from work and try the radio and the depth finder neither work. I check the battery again and realize I hooked the negative to the positive and vice versa. I change them back and now the horn and bilges work but the radio and depth finder are dead.

Sooooooo. Does reversing the power cables destroy depth finders and radios? If I have to take the deck off again I might just grab my Uzi and head to McDonald's. (Just kidding, ATF)

PS fuses are all good.

Did you try hooking up the power to the stereo on a jumper wire to see if it was OK? The stereo has an inline fuse in addition to the fuses on your boat. If you can check the wire with a meter and see if you are gettin juice.

The depthfinder runs on its own circuit, the radio is a UHF radio and both have inline fuses that are okay.

Isn't there a tester that detects current in the line itself? If not I guess I'll try cutting the power wires at the devices and connect directly to a battery.

Sorry to say but most of the more sophisticated electronics do not like having the power reversed. Some have reverse polarity protection built in and some don't.
The do make clamp on dc amp meters that you put around only one of the wires leading to the electronics BUT, they usually don't work well in extremely low current applications. Usually in radio/depth finder current use you would use volt/ohm/amp meter by switching the leads to different sockets on the meter and then switching it to dc amperage on the selector switch and connecting the leads in series with the load/(electronics). If you screw up here you can pop a fuse it the meter itself or fry the cheap-o meters (I've done it).

I would try disconnecting the battery, drink a beer, pray, drink another beer then reconnect the battery correctly and see what happens.
If that doesn't work you will need to measure the voltage at the input of all devices not functioning.
Check for more of those resettable breakers.
If it all goes bad and you've fried your electronics they MAY be repairable by replacing some detective electronic components by an electronics shop if those still exist.

Good luck
Doc

Oh yeah....WARNING....if you do use the volt meter for current readings be sure and swap the leads back BEFORE you attempt to measure voltage again. This is a sure way to pop the fuse in the meter or elsewhere.

In case anybody's interested I cut the power cables and the positive including switch and fuse was good. The negative was also good. Looks like reversing polarity on an old (8 yrs) Lowrance really does screw it up. The radio just blew a fuse, I didn't check the correct wire before.

Oh well, BPS has its grand opening this month, maybe they'll have some deals.

Bummer!