NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bob Bossert
Date: 2025 Sep 4, 06:00 -0700
I mostly sail on Lake Ontario and St Lawrence, with a few cruises along the Atlantic coast.
U.S. Great Lakes Charts of Michigan and Huron were Polyconic, not Mercator. Over 120 years ago, Polyconic was choosen for these two lakes because they are primarily aligned North-South, versus East-West. One of the reasons given was that Bearings on Polyconic charts for North South aligned bodies are more like what you'd see on the water versus Mercador. Before GPS and Loran that advantage made sense. I imagine at one time most of the US major rivers were Polyconic for the same reason. A little over 10 years ago, I read that there was pressure to change US charts to be Mercator only. Anyway, I just downloaded some of the new (Sept 2025) ENC NOAA charts for Lake Huron and they appear to be Mercator whereas my "out-of-date" RNC (Raster) charts that I downloaded only a few years ago are Polyconic.
What are the African countries proposing to replace Mercator?
