Geoff,
I think a radioship could earn a profit if it were licensed. If built properly it's signal coverage would be noticeably greater than ANY equivalent power land based station due to the excellent ground conductivity of sea water.
However, as a pirate, advertisers would be hounded by the authority's, through the Euro courts if necessary. No revenue = no supplies = no signal.
Fortunitely there are still several UK and Dutch engineers that know what needs to go into building a first class radioship.
You then only have the not so easy talk of giving the people a reason to listen to the station. Easier said than done.
