As I said, I am not a seasoned salt on the electrolysis issue. Assuming the sacrificial plates on the rudder have helped (has this been shown to be so?), then perhaps the sacrificial plates prevent leaching of one of the metals in the bronze/monel shafts.

The issue is that, without an electical connection, i.e. the shafts being isolated, how can there be currents, even at the dock? Perhaps this is just showing my ignorance of the electrolysis issue. Something to work on next year.

With other items, there is a "loop" that can conduct the electricity/corrosion (like the outboard motor).