Boundaries of a complete electric overhaul

Absolutely right papabravo. My wife used to laugh at me. I'd bring that book to bed at night. She said "When are you going to get another book? Aren't you done with that one yet?"

What she didn't understand was that I was rereading the text again and again as I pulled my old boat apart. You may have gremlins. I had a birds nest. It wasn't all bad though. My boat was a textbook example of how not to wire. My two favorites were the 40 ground wires stacked on a small bolt that was attached to a partition behind the helm, and the ROMEX that made up my A/C wiring. The previous owner had a Square D box connected to the shore power cord with a couple of domestic single pole breakers. He owned the boat for years and hadn't electrocuted himself but....not good.

 

How long does wire last ?

I asked this question to a Professional Marine Electrical engineering company in the Netherlands. He replied 25 years if correctly installed and operated.

My experience says this is correct. With age the insulation on wiring become brittle...particularly outside radius and wired subject to heat...engine rooms or high tension junctions.

 

I suggest that the lifetime of wire insulation is extremely dependent on the exact composition of the insulation.

 

The insulation is only part of the issue. Cut the suspect wire, well back from any connectors and strip the insulation. Examine the wire, it's usually pretty obvious. Conversely, the first thing I do is pull an ohm test, assuming continuity is there. On old wiring, I most often find a bird's nest or hacked up, spliced and cobbled together crap, which is why it's usually easier and cheaper to just hank it out and start with a level playing field. Rewiring up a 40' yacht isn't especially costly in materials. There are a limited number of circuits and devices - just layout a reasonable diagram, with room for some expansion and pull some wire.