NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Samuel L
Date: 2015 Jan 19, 04:29 -0800
Please tell me if the following is incorrect. If in error, where I'm wrong and exactly what to do to fix it.
In the final analysis here's what I to solve the problem-
1- Calculated Ho for sight 1.
2- Determined GHA and Declination
3- (90 - Ho) x 60= Zenith Distance (yes, I know you all said use Hc but there's no Ap to base it on)
4- Get a globe.
5- Using a globe of the Earth, the GHA and Dec of each sight was used for the GP.
6- A compass was set to the radius of distance found in step 4 and then swept around the globe to lightly draw a Circle.
7- For sight 2- repeat the entire process to draw a 2nd circle.
8- Get the approximate Latitude and Longitude of the circle intersections that is most likely where the fix will be (the guy was obviously not in the Pacific ocean).
9- Use the Latitude and Longitude deteremined in step 8 as the Ap's for determining Hc.
10- Plot the Intercept and Zn.
It was surprising how well that method worked out. Even with an Ap error of 1 or 2 degrees a fix was obtained within several miles of the actual location after 1 try.
It all made a lot more sense when I was reading in Dutton's book, Navigation and Nautical Astronomy, about Circles of Equal Altitude.
A globe is nice but it would be cleaner if a flat map could be used. What projection of map should be used?
