Europe public utility power is 240 volts, 50 Hz. The outlet is hot and neutral with no ground since neutral is ground. It is in the US too, but codes require a separate ground wire. The key is to find out what is being delivered to the boat's power inlet. If you are using 120 volt appliances and lights you would probably know by now if the outlet is 240 volts, but you should measure it with a volt meter to be sure. The normal wire jacket color for European power is brown on GB Boats. To meet US standards you will need to add a ground wire and change the outlets. To remove the outlet unfasten the screw in the back of the middle of the outlet. If the boat is in fact wired for 240 volts you can use a step-down transformer. If you have some 230 volt equipment on the boat you may need to have both 240 volt and 120 volt outlets which is possible with a 2-tap transformer. In the US 220 volt power is delivered with two hot wires and one neutral at 60 Hz.