NavList:

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?