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
    Azimith forumula for Great Circle sailings- having problems
    From: Samuel L
    Date: 2014 Dec 23, 14:41 -0800

    I use the following formula to obtain Azimith-

    Z = tan-1 (sin (LHA) / (cos (LHA) x sin(AP Latitude) - cos(AP Latitude) x tan(Declination))

     

    If LHA is greater than 180 it's treated as a negative quantity.
    If the Azimith angle as calculated is negative, add 180 to it.

    In one Great Circle sailing probelm I'm working on to determine Z the answer is negative unless the LHA is entered into the formula as a negative number. The answer should be about 3d 55min. If I add 180 to to the negative answer the wrong Z is obtained.

    tan-1((sin(LHA) / (cos(Present Latitude) x tan(Destination Latitude) – (sin(Present Latitude) x cos(LHA))

    Here's the figures;

    LHA= 0d 9m 40.9sec

    Present Latitude- N 39d 58m

    Destination Latitude= N 41d 43m 31.8sec

    The answer I get is -3d 55min (notice the negative sign.

    It would be nice to have an Azimith formula that's independent of Hc and provides the correct figure regardless of LHA greater or less than 180d.

    How do I solve this problem?

    Thanks,

    Sam Lohengrin

     

     

       
    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