Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
    Re: The Maths behind DSD
    From: Greg Rudzinski
    Date: 2017 Oct 8, 18:11 -0700

    Eamonn,

    Attached is a graph solution for DSD from page 527 of the 1977 edition of volume 1 American Practical Navigator (Bowditch).  The interpolation tables are linear which normally will be good enough.  Pub 229 uses Italic type and an asterisk where the DSD correction exceeds (0.25').  An eye ball interpolation might be more practical rather than fooling around with graphing or double interpolating. 

    Greg Rudzinski 

    From: Eamonn Sparling
    Date: 2017 Oct 8, 16:38 -0700

    I am new to Astro nav and I like to use pub. no. 229. I think I understand how and when to apply double second
    difference, I will probably never need to. My curiosity relates to understanding the concepts supporting DSD
    and what is he relationship between the DSD and the required (extra) increment value of Hc. This is not intuitive to me.
    I would like if the forum could explain this mechanism, or direct me to the maths behind this concept.

    Thank you, E.S. 



    Attached File:



    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