SHIP'S LOG:
Trace a wire from one end to the other. What could be simpler? But it is not as simple as it sounds. Tracing the wires for the engine gauges required getting access to the engine which meant opening up the side panel, the front panel and the floor panels in the "In-Law" apartment cockpit locker. Even then, it was not all that easy a tack for a couple of reasons.
The first is that the manual I had for the engine is gone. It disappeared during one of my sojourns on the hard after the groundings. Someone, for whatever reason, "borrowed it and never brought it back. So any and all directions and descriptions of the wiring is gone.
The owner's manual, which I have, depicts the wiring as it originally came from the factor but it has been "modified" over the years and most actually bears little resemblance to what it originally was. Fixes and adjustments by the owners, crazy wire routing and bundling makes tracing a
horror show.
Then there is that routing and bundling. Wires need to be support along their length, ideally ever 18 inches(to keep to code) and to prevent them from dangling and getting snagged and/or ripped out accidentally. It is hard to follow a wire in a bundle through a bulkhead or wire run and be sure of where it actually goes.
Then there is the wire color coding. Specific color wires are used for specific jobs. They all had the correct color s when they left the gauges but some "miraculously" changed colors somewhere along the way. It is a case of using whatever wire of whatever color to affect a repair. It is a total pain.
Then there is the crazy and non-code and unsafe connections that show up along the way. It is something akin to traveling on a freeway through a monstrous work site with all sorts of detours and changes of direction. Just trying to figure what goes where is one hell of a challenge.
One could try to work backwards, going from the appropriate sensors back to the gauges. I tried this but just finding the sensors is a challenge. When I first go the boat, it took me a whole day of dedicated and focus investigation to find the oil dipstick! It was actually hidden behind two hoses which had to be moved to access it. Things are like that on ABISHAG. The diesel fuel filler is "hidden"in the propane lock. I got a call in the fall from the boatyard wanting to know where it was as they couldn't find it. It took me most if the afternoon to find the oil pressure sensor and the engine temperature sense and I was able to accomplish that only by means of a process of elimination. The only wires "connected" to the engine should be those leading to the alternator and those to the sensors. But there are wires that lead over, under and around the engine and it is a task just to figure out which one actually go to the engine. Access to the engine on a boat is not like that on a car. Usually you have access to one, perhaps two of the six sides. Of course it doesn't help matters that there are also wires that are near the engine that are connect at that end to nothing. what a chore!
If I had the bucks, I would rip put every single wire, bus bar and panel, and re-wire the entire boat, marking every single wire and c0onnection as I went and creating an accurate electrical schematic. That will have to await a visit from the Prize Patrol from Publishers Clearing House! ! !! ! ! ! ! !