You probably will still have issues even using a voltage converter.  Most cruise ships' power is 'different' from normal power, not just different voltage, or even the amount of power, but the way the power is delivered.  On a standard 120V AC circuit you have 120 volts (to ground) on one leg, zero volts (to ground) on the other leg and the third wire is an earth ground.  On a ship you have 60 volts on each leg (120 volts between the two legs) and a "floating" ground.  Converting the 220 volt AC