Chuck,

I don't agree with your grounding advise.

If you ground the frame of the transformer to the boat ground and there
is an internal short from the shore power primary winding to the frame,
there is no return path for the current so you will not trip the supply
breaker.

In addition, you now have the boat ground, including underwater metal,
live at 110 or 220 volts which can electrocute persons in the water or
boarding from a metal dock.

Andina Marie