Wayne.B wrote:

Back in the 70s, pre-LORAN C, we used to DR from P-town to Maine on
a fairly regular basis. Plus or minus one mile after sailing 100
miles was fairly typical but maybe we were lucky. That one mile at
the other end can still loom large on a foggy morning at 6:00AM
however.

I don't doubt that one mile can make a big difference. On my first trip to
Pubnico NS I entered through Lobster Bay in "thick-o-fog" and somehow
managed it with little instrumentation (in particular no Loran or GPS or
radar). It was only much later that I understood the dangers due to
current, really dangerous shoals, etc. On my last trip, in good visibility
and with a bevy of tools, I noticed just how much we were pushed about by
the tide and how much of a chance we had taken almost 2 decades earlier.

More info is better.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://kerrydeare.home.comcast.net/