The minus potential of the DC system on the yacht is grounded. In particular, the minus terminal of the alternator is connected to "ground" (i.e. sea water) via the engine and the drive shaft as well as the minus terminal of the windlass via the chain cable.
The AC connector for on-shore power is IEC 60309, L+N+PE, 6h. (In German that connector is colloquially called "Campingstecker".) This connector also provides a PE and is connected to on-shore ground.
I plan to use a VE Phoenix Smart for AC/DC conversion and battery charging. The Phoenix Smart does not require a PE.
I am wondering if I should connect the on-shore PE with the yacht's PE.
Intuitively, I drew that connection into my wiring schematics, because it felt wrong to leave the on-shore PE unconnected and as a dead end.
On second thought, I figured that it might be a bad idea. If the on-shore PE potential was different from sea-water potential, equalizing current would run through the minus conductor of the yacht.
Of course, normally the on-shore PE potential should be identical to the sea-water potential. Everything else would mean that the on-shore electrical system is faulty. But who knows?
Any suggestions or recommendations?