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.