A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Nov 26, 16:31 -0800
If the mirroring process and imagining a virtual barn on the other side of the river seems too weird, you can also do it by similar triangles on one side of the river. I think the image below is probably self-explanatory.
Sorry if we're beating a dead horse. Solving optimization problems, like weather routing, in navigation really does bear some resemblance to solving optics problems. And getting where we're going in optimal time is certainly at the heart of all scientific navigation.