interesting the definition of coasting.
Maybe one has to look at the deck certificate of competancy limits?
Home trade the UK North Sea-Irish Sea, Elbe and down to Ushant , note not the Faroes. And Middle waters Norway, Baltic and down to GIB, maybe the meddi.?
Fishing Near waters and then the distant water limits, and finally foreign Going -world wide.
Passenger ships are more defined.
The general definition may be found as guidance in the MS Acts Life Saving Appliances.
OFF course this could be all balls.
Not forgetting the articles Foreign going 2 year agreement, 6 months running agreement, and then the home trade. OF which you are wishing to be defined