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    Re: T Hav Doniol Sumner LOP Example
    From: Brian Walton
    Date: 2019 Mar 9, 22:31 -0800

    Lars,(and Greg)

       A brilliant 3 word explanation!  Thank you.  I did wonder in my 5 Mar post if units were the problem, or, unsaid, radians.

        CN is for fun, or serious analysis. If you are still operating a vehicle solo where you need hands-on to steer, and must also look out and navigate, mental calculation comes into it.  Head down, get run down.  Aviators, with fuel running out,  were quick to realise that a correction of the right order, in the right direction, done immediately, was better than a four place calculated correctionl applied many minutes/miles later.  The 1 in 60 rule etc.

        The numbers 1.9635 and .5235 scream at me, use 2 or half. 

         Those  sailing across the Atlantic around 1890 for a living, at around 50°N, using ex- meridian calculations daily for Lat, crossed with time sights, (my greatgrandfather) , would have realised that the correction for minutes of time early or late, falls close to an answer of about 1 mile per minute, provided you were within about 20 mins of merpass.

          Is it possible to simplify the all hav ex-meridian layout?

    Brian Walton

    50N 01W

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