Doesn’t work on Mercator charts latitudinally
either.
But it still ain’t the point boys.
“Paul,
I'm with you. I'm calibrated
in MPH (statute)
However, a little background.
One nautical mile is exactly one
minute mark on the vertical scale of a marine (or aviation) chart.
This doesn't work with the
horizontal scales as they shrink towards the poles.
Having this simple measure so
readily available, the early navigators fell into using Knots.
It still is very useful when using
charts.