Since all the appliances are designed for 220 VAC and 50 HZ, the boatowner has 2 significant challenges:
1) Since all the wiring is for 220 VAC it’s half the required size for 120 VAC. Therefore to run off 120 VAC, all the AC wiring aboard the boat needs to be changed.
2) Since most of the appliances, like thehot water heater, are meant to run at 50 HZ, they’ll need to be changed to run at 60 HZ.
Overall, it’s a very involved process. I’d budget about $10K in labour and supplies to get this done.
I have attached a Pacific Yachting TechTalk Column we wrote on exactly this process or you can follow this link.