I know someone who installed a frequency converter transformer in his boat. It cost significant money, space volume and weight.
Of course, an equivalent outcome can be achieved as follows:
1. Have a battery charger that can accept 90V-to-250V and 50Hz-to-60Hz, such as a Mastervolt, or any other brand.
2. Have an inverter that puts out the type of power you want, such as a Xantrex Pure Sine International 1800W/230V/50Hz, or any other brand.
Result ---> You can now power any suitable appliances from your inverter, regardless of the type of shorepower you have, worldwide.
SM2K N. 350