I'm planning a cruise to the same area (southern Newfoundland) so I
appreciate the intelligence. I would use the private charts you trust
to enter the general shoreline as a route you can call up on one of
the chartplotter units. A good winter project. It will give you a
visible constant offset from the charted line that you can apply to
courses and navigational dangers. In some areas you might want to
simply enter a line to remain offshore from. The route names could be
used to indicate which method applies.

If you are a Garmin Bluecharts user, you could save this work in a gdb
file to share with others (like me It doesn't sound like you are
using Bluecharts but, if so or something else that can load gdb or gpx
files, contact me privately. I have the means to load and scan charts
into AutoCad so that lines can be traced and their properties printed
out in text files which would give you lat long points to enter. Gpx
files are in ASCII format so, given some time, I could write a program
to process the text output from AutoCad into gpx files that could be
read directly by a number of GPS plotting programs. I used to do a
lot of this text file string manipulation. There may be simpler and
more direct approaches but this is just what occurs to me off the top
of my head. I might have plenty of time this winter to work on
something like this and it would be well worth my while as a way to
become more familiar with the area and the charts.

BTW if I had a functioning Loran on my boat, I would keep it as a back
up considering the things that could shutdown GPS although I wouldn't
go out and buy one for that purpose. I also used Loran in my airplane
because it worked well enough that I couldn't justify the cost of a
GPS. Aircraft navigation, VFR at least, is a lot less precise than
marine navigation however. When you get within 3 about miles, you
switch to eyeballs.

--
Roger Long