A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Greg Rudzinski
Date: 2017 Oct 6, 12:05 -0700
The Davis MK 3 accuracy is in the + or - 8' range out of the box. Better results are possible but you have to earn it. Plastic sextants will warp in direct sun light or if squeezed too hard. I zero the index error before each observation then check again after the observation. Even if everything is done right there will remain large systematic errors. Below is a set of 5 observations using a Davis MK 3 and a liquid artificial horizon today. Good enough in a pinch but not very good as a primary sextant.
The MK 3 is very good for horizontal sextant angles, and relative bearings off the bow. Sailboat racers can use to see if gaining or losing on a competitor.