- Keep the water out of the boat
- Keep the people in the boat
- Keep the boat moving
These are basic adages, useful for staying out of trouble, but modern boaters desire many of the comforts that technologies offer. A boat’s electrical system and its management is integral. Consider what items might become unavailable without it. I have a list in my head because one learns to play “what if” scenarios and plan for contingencies and prepare backups.
Without electricity, for example, you lose the ability to heat/cook food. This is because the CNG fueled galley stove has an electric solenoid valve at the supply tank that is safety mandated to help prevent accidental gas leakage from becoming deadly. This valve is powered to the open position which means that without — it’s shut. Cooking fuel not accessible.
The boat does have storage batteries and these are isolated so that if one goes the other is backup. The engine, when running, has a generator. So, imagine my shock (no pun intended) when all went dark. Not literally; it happened to be the middle of the afternoon. But it also happened to be the middle of the big wide open ocean miles and miles from land. There was a thump noise and my first observation was that the steering autopilot was offline. Further investigation revealed that the navigation chart plotter and associated electronic aids were down. Going below I discovered that lights, radios, pumps all via the panel could not be switched on. The diesel auxiliary could not be started. There was no power whatsoever. Total loss!
I began a futile search for some sort of Main Circuit Breaker… knowing that there wasn’t one. I opened the master electrical panel to see what I could see. I felt like the driver disabled roadside opening the hood of his car looking in thinking he’d see something obviously wrong but only staring into unknown complexity. I crawled over the diesel into a small space under cockpit deck to go hands on with the batteries. Nothing obvious there either until I stumbled upon the culprit.
Checking security of the battery cable connections I found one awry. Not apparent by eye, a cable was loose and the problem obscured by black electricians tape. 
This wiring, a crucial common ground, had separated from its terminal lug. The original solder joint had failed. The black tape held the cable near but the detachment prevented the circuit. I removed the tape and with Leatherman stripped insulation to reveal more copper. This bare wire was inserted at terminal junction under the other lugs and the whole shebang secured. This was a bandaid fix but I was back in business and on my way in short order. Upon arrival at my island destination I endeavored
to replace the offending terminal lug. I didn’t trust the bandaid to get me back to home port. After learning at the auto parts supply that these items were available only on prefabricated [short] cables I visited a hardware store and found a grounding cable clamp that gave me the idea for a MAcGyver fix. I stripped insulation from another cable and siamesed the two so as to share a good terminal lug. This was still ugly but secure. Happily restored, the electrical system held together on return voyage and meals were served hot — and the electronics worked, lights, and toilet. Yep. It’s electric too!