The hard limit on naval radar is the horizon which is determined by the height of the mast it's mounted on so much of the sea's surface at any given time isn't

The hard limit on naval radar is the horizon which is determined by the height of the mast it's mounted on so much of the sea's surface at any given time isn't actually covered by radar. Even when a ship happens to be on radar there's no indication of what ship it is without a transponder like AIS.