The following will give you an idea of world voltages Electricity Around the World
220-240/50hz is probably more predominant.
Ref SWW's question my understanding is post WW 2 when Europe
was being re-built they took the decision to change from 110 to 230V for the greater efficiency. It was considered in USA & Canada
but the decision was too many existing appliances
would have to be junked, so they decided against it, which means you are forever saddled with a less efficient system (110V reuires 30% more copper for the same kW rating and has greater voltage drop). Interestingly enough the most efficient single
phase is 230v/60hz. Most of Sth America is 220V/50hz but Brazil
is different (as always) - the south east (Rio, Sao Paulo etc) is 127V/60hz whilst the north is 220V/60hz.
Back to the original question - depends on what loads you intend to have on the yacht, will you have a generator
and will you spend most time at anchor
If you want air conditioning
then you need an AC generator. A 60hz generator is more efficient because it is running at 1800rpm, as against 50hz at 1500rpm. For time alongside fit a dual voltage transformer.
If you don't want airconditioning I would suggest an inverter/charger for any AC needs, or if you are likely to be along side a fair amount of time separate inverter
and dual voltage charger
. 110 or 220V - I suggest wire for 110 intially, you can get the gear
cheaply in the US, if later on you decide 220 would be better (probably because you cannot replace broken applicances) then the change is easy because you do not have to touch the cabling.