It might be better to list the things that have failed in my last 6 years and 1400 hours.
Delco alternator internal voltage regulator drove volts up to 17.5 and I suspect ultimately killing a pair of 8D AGMs. Replaced with 105 amp ARCO alt and 6 golf cart batteries.
Alt belts. The new alt pulley took 10 MM belts and was slightly smaller diameter. They didn't last long pulling 105 amp. Changed pulley to 13 MM and increased diameter to the original 3 inch pulley. Now belts going 400 hours between adjustments.
Jabsco raw water pump seal leak was slow enough to replace pump at the dock.
Jabsco Electric macerating head. 2 heads failed twice. Heads replaced with Raritan, now have 3 orphan rebuild kits. Send me a PM if interested.
Perkins Exhaust adapter corroded after 36 years and leaked out all of the engine coolant. Pulled cyl head and replaced all valves, seals, springs, hoses and gaskets.
Westerbeke 8BTD would not start after storage. Ran ok going into storage. Found all 3 cylinders at 270 psi compression. New gen.
Simpson Lawrence windlass jammed trying to retrieve anchor during a blow. Something broke inside. Bolts would not come out to open it up. New windlass.
Jabsco holding tank macerator pump impeller. It stopped pumping when only 3 vanes were left out of 7. One occasion when I had an entire brand new identical spare replacement pump on board!
If I think of anything else, I'll add on here.