We spotted the Norwegian Jade cruise ship from the beach at Rosemarkie. If my little finger subtends 1 degree then the ship subtends 1/6 of a degree or 0.0029 radians. If the ship is 50 metres high, it means by the arc length rule that it is about 50/0.0029 = 17188 metres away. 17 km is about 10 miles.
