Rewiring The Boat

April 17, 2014

I was sailing at night once, in some nasty weather, and my running lights went out.  Turns out a chafed wire was the problem.  My son fixed it for me, but I committed then to rewire the whole boat, by myself, before the SHTP.  I wanted to know where every tinned strand is, and what it does.

Well, it’s almost finished.  My mast is down now because I’m having the sheaves replaced at the top and in the base.  When the mast goes back up next week it will be better than new, and it will have a new tricolor, strobe, anchor light, and VHF/AIS antenna.

Back to the wiring.  I’m not dumb, but 12 volt marine wiring was a pretty steep learning curve for me.  I travel between Spokane and Port Townsend, and I wanted time to get it right, so I took the whole panel out of the boat, brought it back to Spokane, and spent the winter figuring it out.  Nigel Calder’s writings were a huge help.  I also relied on the SHTP electrical seminar notes published by Michael Jefferson.  In fact, my wiring diagram is pretty much taken right out of his seminar.  Between those two guys, and hours of looking things up on the internet, and asking some patient people the same questions over and over, I finally got it.

I have two new 6 volt golf cart batteries wired in series for a 12 volt, 232 amp hour bank.  I have the original Optima group 31 battery, at 75 amp hours, wired to the battery selector to be used as a spare.  Each bank is fused at the positive terminal.  I have a 1.5 amp charger wired directly to the Optima, so that it’s always full when I leave the dock.  The main bank is supplied by a 55 amp three-phase charger.  I have 100 watt and 25 watt solar panels with charge controllers.  The outboard alternator is wired into the positive distribution post.  There is a 2000 watt portable inverter generator,which easily runs the 55 amp charger.  I’ve completed the SHTP electrical budget worksheet and figure that, with no sun at all, I can go about four days before I’ll have to break out the generator.


The final result. The sink will go back in. I don’t use it as a sink, but it’s a great place to store wet things.

Here’s my new panel.  The radio on the left is the new Standard Horizon VHF with GPS and AIS (receive only).  Its antenna is at the masthead.  It allows you to set up a perimeter alarm, which I plan to do.  My MMSI  number is programmed in, so that radio is good to go.  Right next to it is the receiver for the Madman autopilot remote, which I love.  The battery selector lets me switch to the Optima backup battery if I need to.  The switch in the lower center is the panel power switch.  Right next to it is a Victron battery monitor for the 232 AH bank.  Both switch panels are waterproof.  There are two 12V powerpoints on this panel.  The one on the front has two USB ports in it.  The Garmin GPS is wired into the spare VHF right next to it.  It can be removed in seconds for portable use.  The spare VHF has its own antenna on the stern rail.  It also is programmed with my MMSI number.  The stereo is above the spare VHF.  It can play and charge almost anything with a USB connection and MP3 files.

All the cabin lighting is now LED.  Four lights are wired into the main bank, and five are battery-powered.  The running lights are LED.  The masthead tricolor, strobe, and anchor lights are LED.  All the wiring runs through conduit.  Before, it was run behind trim pieces, which made it tough to get to.  Now it’s a breeze.

Terminal block

This is one of the terminal blocks, where the positive leads are collected and sent to the panel.  Everything is heat-shrunk and labeled.  There is not much room behind my panel, so the fit is pretty tight, but it’s all easily accessible.


This is the back of the panel about halfway through the fabrication process. There’s a lot more wire in there now, but I can tell you what every single one of them does.




















I posted some other pics on the Boat Preparation page if you’re interested.  One thing I did that helped me a ton was to get two 6 volt lantern batteries and wire them in series.  That gave me enough 12 volt power to test every circuit before I even left my kitchen table.  If you know what you’re doing, this probably seems unnecessary.  I don’t, really, and I wanted to know that my new panel would work properly as soon as I turned the battery and panel switches.  It did.  Whew.

I made a few mistakes here and there installing everything, but nothing was critical and I learned a ton.  Everything works like it’s supposed to, and boat wiring is no longer a mystery to me, which was my goal.

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