A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2017 Apr 18, 00:39 -0700
Thank you for bringing this up! I was about to ask a similar question.
Every weekend I come to the shore to practice the sights, it goes like this: I take 4~5 sights with 2~4 minutes between them, then I do the reductions which takes ~25 minutes. Then I take the next series of sights and so on (until I'm hungry and go for BBQ).
The conditions three weeks ago on the Finnish Gulf were a sunny day, rather warm air but solid ice covered all the gulf area. The horizon line is uninterrupted within 3 nm from my favorite observation spot.
All the sights were placing me within 2~4 nm from the GPS position I know.
Suddenly - all the five sights I took in one series started placing me well 50~60 nm away!
Puzzled I took the next series of sights - those again put me back to 2~4 nm from my GPS position.
What was that? Could I make a ~one-degree error reading/writing the measured angle in all five sights in a row? Or was it something with the sudden refraction change?