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    Re: Emergency navigation: a Cruiserfix tool.
    From: Francis Upchurch
    Date: 2016 Sep 1, 05:10 -0700

    Thanks Tony,

    I'll probably build this during the winter just  for fun. Have you done yours? If so what sort of accuracy? 

    It looks a simple tool based on sun dial and corrections from  equation of time graphs and rough declination tables. Can't see it being very accurate, but should be fun. 

    For accuracy, I have found using a basic Davis 111 plastic sextant, using only meridian passage  sun sights, declination tables , EoT tables and simple mental arithmetic, I can usually get to within 10 ' latitude and 15' longitude.( Longitude by estimating LAN from a graph of multiple before and after sights.) So I doubt whether this could match that, but fun to do.Still need a quartz watch for GMT though, but I now sometimes  do my "no clock" longitude using lunars, just for fun and have so far got to within 15-30 miles (occassionally more like 60 miles, but I consider these "outliers" and cheat by ignoring them.)

    I recently improved the accuracy of my homemade nocturnal by increasing the size and adding vernias .(used for polaris latitude correction without tables). Also has simple bubble level to help keep things horizontal and perpendicuar. So I may incorporate these "improvements" in my Cruiserfix build.

    Many thanks again

    Francis

       
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