Half an hour after leaving Fernandina Beach, the GPS mysteriously went blank and the SSB radio clicked off. We just turned them back on, shrugged our shoulders. and put it down to "a power glitch". Lesson #1: Never ignore anything unusual that happens on a boat, no matter how trivial it seems.
Half an hour later, while I was heating some soup for lunch, it happened again. This time, Britt thought he smelled smoke (and it wasn't coming from the soup!), so I turned off the stove and took the wheel while he opened the engine compartment. It was filled with a light haze of smoke, and a little flame was coming from the alternator regulator.
We quickly shut down our electrical system and doused the fire (more like blowing out a candle, as it fortunately wasn't very big!), then I turned off the engine and coasted to the edge of the channel as Britt dropped an anchor. As soon as we were satisfied we were in a safe place (for both ourselves and other boats) we investigated the damage. Two small ground wires on the regulator had shorted out against the alternator power connection; probably the constant vibration from the engine had caused them to rub through their insulating covers. Our fuses are on the positive side only, and the alternator power is connected to our main electrical system 400A fuse. The small ground wires which shorted couldn't handle that load, so they gave way long before the fuse would have blown. The regulator was a charred mess of melted plastic, but nothing else appeared damaged.
The really upsetting thing about this was that it had happened before, back in June. The alternator positive cable had shorted out against the negative bolt and blown our big fuse. We'd solved the immediate problem by rerouting the cables, but the fundamental cause was really the vibration of the engine, and that's something not so easily solved. Lesson #2: Vibration happens. Regular checking of all the electrical connections on the alternator is just as important as checking the engine oil.
We disconnected the regulator and turned the power back on. Everything seemed ok, so we got underway again. With the regulator out of commission, the alternator was no longer useable either, so we had to run off our batteries until we could get to a marina and connect to shore power to recharge them. Fortunately, our batteries were fairly full, so we anchored that night as planned but headed for a marina in St. Augustine the next day. (If we had been offshore, or unable to get to shore power before our batteries ran out of juice, we would have removed the big alternator and re-installed our old alternator, which has an internal regulator.)
We had been dissatisfied with our mail service, so in Fernandina we had contacted another service, St. Brendan's Isle, and set up an account with them. Their office is not far from St. Augustine; since we needed to sign some papers, Tom, the owner, suggested that we call them when we arrived, and he and his wife would come out and meet us over dinner (with the papers). One of the services they advertise is that they can obtain parts from West Marine and other marine catalog stores at a discount. I felt a little guilty putting them to the test so soon, but our anchorage had a pretty good cell phone signal, so I called and asked, "Could you bring a replacement regulator along with that paperwork?"
We arrived in St. Augustine the next day, and that evening Tom and Jackie arrived, regulator in hand, and took us out to a great dinner at the Conch House. Now that's what I call service!
It shouldn't take long to install the new regulator and get it up and running. This time, we will take more care in wrapping and isolating the wires, and we will be sure to inspect them frequently. Fire is one of the most serious and scary things that can happen on a boat, and if it happens again we might not get off so lightly.