All good advice, but the voltage to the volt meter on your boat is the voltage that is most important. It also can tell you the condition of your cords, connection points and wiring from the main panel to the dock outlet. For instance if you have 115 volts at the dock and 105 volts at the meter on your boat, you probably have a corrosion issue of some kind. If you have 115 volts on your boat and turn on your a/c and then read 105 volts, you have a different problem but one that needs to be addressed also. Either one will ruin your equipment before it's time.
Billy K.