Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Bermuda to St Helena on a North Atlantic Mercator Chart
    From: Lars Bergman
    Date: 2021 Dec 29, 10:31 -0800

    David wrote "There isn’t a difficulty.  It’s proving the thesis that, if the great circle is north of the rhumb line in the Northern Hemisphere and south of the rhumb line in the Southern Hemisphere, then the great circle and the rhumb line must cross the Equator at the same longitude that concentrates the mind."

    The GC and RL cross the equator at the same longitude only if the start and end positions are symmetrical, i.e. the same latitude but different names. For the Bahamas to St Helena case the GC cross the equator at W 23°5' and the RL cross the equator at W 24°36', calculated for a spherical earth. And the difference in distance Bahamas to St Helena is only 7.4'. 

    Lars

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site