By fixing the ship’s position and then checking Annual Notice to Mariners No. 12 (National Claims to Maritime Jurisdiction). This lists, for all maritime States, the width of the territorial sea (TS), contiguous zone (CZ), exclusive economic zone (EEZ), and (where no EEZ is claimed) fishery zone (FZ).
How can the master of a UK ship determine whether his ship is in a coastal State’s territorial sea?
