NavList:

Robin Stuart, you wrote:
"I wonder whether the association of the UPS with its "Mercator" misnomer might have arisen because parallels and meridians form a rectangular grid in both"

I can imagine that that had something to do with it, yes. I also think there was probably just an accidental naming at some point, like the littleimaginary story I told earlier... some poor guy working on Bowditch or some other manual went to his supervisor and asked what to call the projection on these "little charts" and the supervisor snarled at him, "Don't you know a Mercator projection when you see one?!" These things happen. But I suspect the biggest factor at play here is just the marine navigator's over-use of the Mercator projection generally. There is an enormous amount of "installed base" inertia in the production of marine charts. As Greg Rudzinski noted, nearly all nautical charts are Mercator charts. This leads to an assumption that all charts, except certain strange specialty charts (e.g. gnomonic "great circle" charts), somehow have to be Mercator projections in order to be useful for navigation. Therefore a chart as useful as the "universal plotting sheet" surely must be a Mercator chart! Something like that...

Like you say, it's a "misnomer", and it's an example of the devolution, the entropy in the subject of navigation. We either fix it, or we start worshiping books! ...and maybe stone idols, too. :)

Frank Reed
ReedNavigation.com
Conanicut Island USA