I plotted the range of all NAVTEX stations worldwide using data from Wikipedia. Converted into a CSV Document. Then converted using a python script to a KML file.

Note: If no range was given, I assumed 300nm, which is the average of all other stations.

I even found an error in the data! The station located on the Cape Verde Islands had the wrong coordinates: they used east instead of west.

I'm not sure what the range actually means, as the stations are probably going much further... I think the range is just the ground wave. I'm also not sure if they use nautic miles or km. I assumed that the range is in nautic miles.