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    Re: Great Circle Initial Course Boston to Wellington?
    From: Stan K
    Date: 2017 Dec 4, 21:08 -0500

    I took a look at your Excel spreadsheet, and I'm wondering how the waypoints were chosen.  I was taught to use whole 5º longitudes as waypoints (in this case 75ºW. 80ºW, etc.).  You must be using some rule, but I don't see it.  Oh, now I do - 300 NM between waypoints.  Also, why does it stop at 25 waypoints, with 434.8 NM to go?

    FYI, I have attached two screen shots of the same problem done by Celestial Tools.


    -----Original Message-----
    From: Sean C <NoReply_SeanC@fer3.com>
    To: slk1000 <slk1000@aol.com>
    Sent: Sat, Dec 2, 2017 10:55 am
    Subject: [NavList] Re: Great Circle Initial Course Boston to Wellington?

    I can't remember if I've posted this before, but attached is an Excel spreadsheet I made which uses the formulae from the Nautical Almanac to calculate:
    • great circle distance between two sets of coordinates
    • initial course
    • waypoints along the route (spaced approximately 300 nm apart)
    • course from each waypoint to the next
    • approximate distance to the destination remaining
    It is currently showing the course from Boston to Wellington. The courses between waypoints could be flown (or sailed) as rhumb lines. The sheet is set for manual calculation, so if you input new coordinates you will have to hit F9 to recalculate. The sheet is also protected to prevent accidental editing/erasure of the formula cells. However, there is no password, so if you want to unprotect it to fiddle around with it or see how it works ... go right ahead. I haven't exhaustively tested it, so if you find an error please let me know. Also, the distance remaining column was a last minute addition which I haven't really tested at all.
    Also attached is a zipped .kmz file of the route with waypoints. It was created at the GPS Visualizer website using the coordinates from the spreadsheet. Each waypoint has the course to the next in the description (you can see the courses by clicking the waypoints or expanding the .kmz in the sidebar).
    Sean C.

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