A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David C
Date: 2020 Jul 20, 20:01 -0700
The depth of the tunnel (as I called i) is in fact the versine or bend of the curve.
A formula I have found in a book published in 1958 is
bend in inches = chord in feet squared / 44 / radius in ch
Now I know why the metric system is superior to the Imperial system that is still used in at least two countries! (I am not sure about Canada - it is probably constrained by its neighbour).
chord = 266 nm
= 1,616000 ft
radius = 3444 nm
versine = 187191 inches
approximately 4.8 km.