A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2019 Feb 27, 02:48 -0800
In the video you posted there is a bit where the captain makes adjustments to GPS's value of magnetic course (if I got it correctly).
Why is that? What's for?
I thought (by my everyday experience with a street-level orientation by a smartphone) - any digital map used in a GNSS device already has a per-location value for magnetic deviation|declination.