Boat alternator problems

by Edward

I have an I/O Volvo Penta 4.3 l gasoline engine and I have for more than a year a problem that the diode of my alternator goes bad. Each time when the mechanic changes the diode on the alternator it comes back and everything looks fine. After a week or two sitting on my drive way with the battery switch in the off position, I try to start the boat again and it fails. No power is coming from the alternator to the fuel pump and the engine doesn't start.

This is my fourth alternator and it will not solve the problem if I replace it again. There is somewhere in the system an electrical problem which causes the diode to go bad. The mechanic is now proposing to change the whole electrical wiring system??? Can somebody advice me what to do? Are we overlooking something. This problem has started in May last year and haven't been out fishing since that time.