@Patowalker: that's new to me, will check it out. Thanks for a useful reply! Still, it leaves me wanting a quick easy way to plot the rough idea of a potential trip.
@Jonzarno: my sincere sympathy - but I do have some scripting that will (under certain conditions like full moon and/or spring tide) produce a plog in postscript - could come in useful on your thermal wax colour printer, couldn't it? It does, though, rely on a fairly recent version of awk - what's the latest on CP/M?
Last edited by Jan Olieslagers; 30th December 2018 at 19:38.