I have a 240V/50Hz boat presently in the US (120/60). I find as follows:
* A 240V/50A shore power
cord, properly configured, can power most of the systems on the boat from the 240/60 available at most marinas
* Several appliances
(dishwasher, icemaker, washing
machine) will not work on 60Hz -- I need to run the genset to operate them.
* The battery charger
and everything run off the 240/50 inverter
work happily -- fortunately this is most of the items on the boat.
* The 5 a/c units operate, but the manufacturer has told me that it will shorten their life. Their solution is to replace the compressors with 50/60 Hz versions. What will happen by running them on 50Hz? The compressors will die an early death and need replacement. I decided to wait until they expire to replace them.
* When I need 120V onboard (and I do for some things -- charging
cordless drill, for example), I use a 240/120V step down converter.