Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Northern Limits of Magnetic Compass Usefulness
    From: Tony Oz
    Date: 2019 Feb 6, 01:17 -0800

    Dear Bob,

    I experimented with a (supposedly "viking-style") Sun-compass which is much easier to build.

    When the weather|environment permits - it workds just fine, as accurate as a good magnetic compass (accounting for the current value of magnetic declination). I checked it on a sea shore by comparing the N-S line orientation with the actual direction to the Polaris in the evening.

    All you need is the gnuplot package, a bit of level cardboard and a dressmaker's pin (with a spherical top, that's important as a "shadow sharpener" feature).

    Placing the printed scale horizontally and sticking-in the pin vertically according to the pre-computed pin length|height you must rotate the assembly untill the center of the shadow is exactly on the line. At that moment the N-S line is properly aligned with the N-S geographic direction. And as a by-product you will know the Local Apparent Time. No external source of time is necessary! :)

    The PLT file (for my last year experiment) is attached, you will need to update the GHA|Dec table accordingly.

    Warm regards,


    60°N 30°E

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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