NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Modifications to 2102-D
From: Brad Morris
Date: 2009 Apr 18, 16:16 -0700
From: Brad Morris
Date: 2009 Apr 18, 16:16 -0700
Hi Gary That was quite interesting. The 2102D can be quite a useful tool. I perform observations on a south facing beach in the northern hemisphere and have played endlessly with the tool. I just use my to determine which stars would be practical. Since my latitude is 40 north, it places me right between the N35 and the N45 blue templates. Therefore, the altitudes and azimuths given really don't do the trick. I first plot the four navigational planets, the sun and the moon via the red template. Then I use the blue N45 to pick out those bodies which will fall in the section of the sky that is useful to me. Unfortunately, this is only about 135 degrees, so it kind of limits my choices. Once I have the list, I swap over to the Bygrave to calculate the altitude and azimuth of each. That way, when I am ready to swing the arc, I can preset the sextant to the expected altitude and point via the compass. Generally, the star is right in the telescope! My motivation for the 2102E was the lack of a template for my latitude. Gee whiz, I thought, how hard could it be to make one? If you have looked into the excel spreadsheet in any detail, you will note it isn't exactly easy! And if I wanted deadly accurate blue templates, it would be enormously computationally expensive. I would extend the number of points to smooth out all of the straight line, but when I tried this approach, the display was all herky jerky. For making a static template, though, that would be the recommended approach. From other postings in the archives, I get the sense that you really enjoy these non-electronic means of solution. So do I! Have you encountered the "Dunlap Sunrise Sunset Computer" in your travels? A picture of it is in my copy of Dutton's. Looks like an interesting solution to a non-trivial problem. Best Regards Brad --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
