Electrical grounding issues?

[cbrscott]

Any help/suggestions appreciated! I have a Donzi 275 express cruiser with (I believe) a grounding issue. Events: 3 years ago, backed out of slip with shore power still hooked up, cracked plug. It still worked fine, so I didn't replace it. 2 years ago, nav/anchor lights become intermittent when running. 1.5 years ago, after a very rough 30 minute ride, shore power blows the converter circuit breaker after about 30 seconds when converter circuit breaker is turned on to charge batteries (you can hear it buzz, soft to loud and then blow). Two weeks ago, I had forgot about the converter problem until I blew the stereo amp (this may or may not be related). Same day, we stayed late and when I tried to turn on the NAV/anchor lights, they didn't work. Neither did the horn, or the cockpit lights. The other 4 switches work fine (wiper, bilge, cabin lights, blower). Switches test good, and when a ground is applied to the open terminal on the nav/anchor switch, the lights DO come on. I have looked behind the dash, circuit breaker panel, and in engine compartment for loose or unattached wires. None found. No empty terminals found anywhere. Ideas?

[silverghost]

Boats always seem to have electrical problems sooner or later~ especially salt water boats.
Get yourself a good electrical multi-meter and use the 12volt DC scale to check all connections for low voltage.
It could be a bad connetion or wire lug. Take off each connection, one at a time, and clean each connection with a wire brush, scotchbrite, sandaper, or heaven forbid steel wool.
From your dscription it sounds like a bad ground conection. Be sure to check all connections on your engines too; especially grounds!
Fuses & fuse holders and circuit breakers can be an issue also. These mini-breakers are known to get corroded internally and go bad on a boat!
Electrical wire lugs have been known to get corroded and is a common sorce of low voltage!
It sounds like a common ground issue that effects all your 12volt accessories.
When checking 120 volt items be sure to use proper 120 volt AC meter scale !
The multi-meter is your best tool in finding low voltage, or no voltage problems.. Sears, auto stores, Home Depot, Lowes all sell low cost meters!
I am sure it's a simple bad connection somewhere!
We all experience this sort of electrical issue sooner or later!
Good Luck!
Brad Hunter

[cbrscott]

Thanks Brad, I've been checking connections in my spare time. I just didn't know if I was missing something easy, or if there was a common ground point that is known to go bad on my boat. So much for hoping for the easy way out. I didn't think of corroded fuse connections. I'll continue with my t-shooting and start cleaning all terminals as you suggested. I do have a multi-meter I've been using. Thanks again, Scott

[cbrscott]

Problem solved. Bad cockpit light reset fuse shorting to ground. Hmmm, must have been it's time to go. I don't ever remember touching it!