I have long thought that the inherent difference between the fix from the GPS and the sextant (or part of it) is that the GPS datums are spheroids whereas the sextant reduction assumes a perfectly circular world. I think that accounts for a few miles at least. I kid myself into thinking they mean my sights are better than they are. (grin) I have never seen a sextant equivalent datum on a GPS, but my comparisons are limited.

What ya think?