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Wiring issues with 12v electrical system on Hunter 30 sailboat

Nov 14, 2016
Hunter 30 (1978) Milwaukee, WI
I'm a new boat owner and my first foray into boat electrics was to try to install a battery voltage monitor. Got everything seemingly working fine until heading in from sailing and started switching on navigation lights and the (inboard) engine. Whiteish smoke started coming from below the cockpit so I go below and turn the battery switch off. Upon closer inspection, the insulation around the wires was burned through (significantly) in some places. I had the service place I am storing the boat at take a look and their diagnosis was that it is a 'short to ground' and would require running new wires 'from the circuit board up'. Anyone have any experience with this kind of issue and ideas what the cost would be? I suppose some new wiring wouldn't be the worst thing. Any advice is appreciated. Thanks.
Jan 19, 2010
Hunter 26 Charleston
Yeah actually the fourth article on that site is how to wire a battery monitor.

Good luck. This is the right place to go looking for info.
Jun 6, 2006
currently boatless wishing Harrington Harbor North, MD
The problem with shorts to ground is the entire cable from supply to the short melts its insulation. That may mean that you need to run new wiring in places that are not at all convenient to get to. Before you start taking any advice (even MainSail's) you will want to be familiar with how electricity and its basic components work. There are several great books on the subject. Prudent sailors are proficient sailors and being able to make repairs while "at sea" is a big plus. Electricity and sea water are not the best of friends so learning electricity will return dividends when you don't have to call a tow boat to get you back home or can continue a long planned cruse by just finding and cleaning a corroded terminal.
good luck and welcome aboard
Feb 6, 1998
Canadian Sailcraft 36T Casco Bay, ME
It sure sounds like you created a dead short. You really need to start reading up on 12V systems & marine wiring in general. You will begin to learn important lessons such as why EVERY 12V circuit on-board needs to be protected via over current protection (fuses/breakers)... Start with Charlie Wing's Book it is excellent.
Jul 7, 2004
Hunter 30T Cheney, KS
I suppose some new wiring wouldn't be the worst thing. Any advice is appreciated. Thanks.
What's been said already.
Burned wiring/insulation should be replaced. Get some help from someone knowledgeable on electricity. Mistakes will get expensive.
Jan 18, 2016
Catalina 30 Dana Point
Coulda been Topsy.

Coulda also been that there was no way to build a high-voltage DC distribution system because all they had was transformers which work on AC only. And you need high voltage to go any distance with any efficiency.

Anyway, put a fuse on EVERYTHING in a boat. And size em right. A 200A MRBF will not properly fuse a bilge pump. Had a buddies fishing boat almost burn down in front of my house because a wire wore through and hit a ground. Smoke pouring out of where he keeps the fuel tank.. Ahhh, that was fun. (I'm gonna rewire the whole boat for him)

And I still have to help out a friend with a 24' cuddy that had the windlass wired direct to the batts with 2 paralleled 12ga wires. Who does crap like that? I rewired his boat and didn't have big enough cables to feed the windlass, so they're currently not connected and awaiting some 4g to come in. Seriously, 2 12g reds and 2 12g blacks. Guess it was a case of "don't anchor too deep or you'll burn the boat down".