One side of my panel is showing 2 lights which indicates a reversed polarity. Is this a real problem and does anyone know where to best begin looking for the problem. Tim

Wes it correct. It is a very real problem. The reverse polarity lights are wired between the Neutral (White wire) and earth Ground (Green wire). Both of these wires should be at ground potential, meaning the lights should never go on. When those lights are lit there is 120 volts where it doesn't belong.

I would go directly to your power cord tothe dock and disconnect it. Then I would sit down and look at what is going on. Are there two leads going to your boat ( twin 30 amp) if so which one is causing the rev polarity. If you have a 50amp I would also check the connection point on the boat for the power cord as the connector could easily be shorting. After this, if you can not find your problem, call an electrician because reverse polarity is not nice on a boat. Good luck. Oh and you can always have the marina put a reverse polarity indicator on the shower power just to make sure it is not on the dock that is the problem, it could be.