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    Re: Parallel Sailing question
    From: Don Seltzer
    Date: 2019 Aug 1, 09:17 -0400
    I thought that by now someone would have observed that you can't sail from 176.15W to 179.45E at 80° S

    Don Seltzer


    On Wed, Jul 31, 2019 at 5:47 PM Frank Reed <NoReply_FrankReed@fer3.com> wrote:

    Jayson, you wrote:
    "would anyone have a formula for solving this problem:what is the track and distance measured along a parallel of latitude of 80 degrees S from 176.15W to 179.45E"

    Here's the reply I sent you previously by email, just for reference:

    This is a standard "exam" question. It rarely comes up in the real world, but it's a popular "make-work" problem as an example of "parallel sailing" for licensing exams. Just find the difference in longitude between the two points (mildly tricky in this case because we're crossing 180 on the trip). Convert that to minutes of arc. If you're on the equator, then that's the distance in nautical miles. At any other latitude, multiply by cos(latitude). A little advice: be careful when specifying longitudes and other angles and indicate clearly whether you mean decimal degrees or degrees and minutes. The first longitude here looks like 176 degrees 15 minutes W, but because you've used a decimal it could be something else.

    Thank you for continuing the discussion via NavList messages. :)

    Frank Reed
    Clockwork Mapping / ReedNavigation.com
    Conanicut Island USA

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