Boats outside of USA
As a Resident of Non EU Country(USA,Canada,etc,) if you buy a new boat you wont be charged the VAT anyway and you can keep the boat in EU waters up to 16 months..
IF you buy a used EU boat VAT is already paid by the first owner of the boat and you can not get anything back since you did not paid any VAT....
If you sail the boat outside the US waters under USA Flag you have to have Federal registration for all practical purposes.
If you import the Boat you pay %1.5 Import tax plus depending on which state you register, appropriate state taxes.