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Hello Frank,

Welcome to the Navigation Mailing List. I am glad to see that you found
your way over here.

You wrote:

> [...] A quarter-mile is a BIG error, so you don't need the "real"
> conversion formulae. All you have to do is get two corners with known
> values in both coordinate systems (e.g. by picking off two known towns
> and reading off their coordinates from the map) and interpolate.

But isn't this where the rub is? If you have a map that only shows the
UTM grid, but not lat/lon, then you need to go to an external source for
the spher. coordinates. And you have to make sure that the "center of
town" (or whatever other reference point) there is also yours. You might
as well get nice round numbered reference points (in one system) from
one of the on line conversion utilities. You are making a very good
point that it is just linear interpolation from there on.

Herbert Prinz

   

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