I've been having problems all winter with the shore power. When I have the battery charger on there's too much interference for the radio. The polarity light comes on intermittently. Today, after I launched it and connected shore power, any switch I turned on caused the shore power breaker to trip. Help!

It sounds like a ground or charger/inverter proble. I think I would remove the unit and have it checked out. Try connecting a known good load to the charger output & see if it trips. This is a difficult one to solve!! Good luck.