Shore Power Problem

[PeterWright]

I have recently moved my boat to a newer dock in my marina.* I have an on\off switch at my dock for me only and a shared*panel with a GFCI breaker.* The problem is that when I connect my boat to the shore power, I trip the GFCI breaker on the shared panel.
To get things working, I unplug, turn off everything on my boat, plug*in, then turn everything on.* This will then work fine for weeks while I live on the boat, using all electrical*components, inverter, charger and devices.
I realize I probably have a ground fault but there are some other observations that don't make sense to me.
1.* With my boat plugged in and everything turned on and working fine, when I simply turn off the switch at my dock, the breaker is tripped.* Why would disconnecting my boat from the shore power in this way cause this?
2. After the event described above, the breaker cannot be reset.* It trips immediately*when attempting to reset.* At this point, considering the dock switch is OFF, my boat should not be connected at all. But if I just disconnect my boat, the breaker can be reset.* *
i am working on the assumption that the switch at my dock, when OFF, means there should be no*connectivity whatsoever to my boat.**
Can someone enlighten*me as to what might be going on here?

[Statistical]

Originally Posted by PeterWright

i am working on the assumption that the switch at my dock, when OFF, means there should be no*connectivity whatsoever to my boat.**
Can someone enlighten*me as to what might be going on here?

I don't know what is going on but this part is incorrect. Shorepower switch (as in the switch on the dock) likely only switches the hot meaning neutral and ground is always connected. Boat main breaker usually disconnects the hot and neutral but this is not common in US wiring on land (to include dock pedestals).

[smac999]

when you turn off the shore power breaker at the dock. it breaks the hot only. your inverter starts inverting and when it does that it conects the netreal and ground on the inverter output. if the inverter is wired wrong the input (and dock) will also see this netreal to ground bond. this bond blows gfi breakers. though normally these would only trip as soon as you turned the breaker back on, and current started going to the boat, with 2 return paths.

wired correctly this issue doesn't happen.

your's may be this or something else.