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
    Sun Hc using Two Slide Rules
    From: Greg Rudzinski
    Date: 2009 May 30, 11:07 -0700

    I would like to propose a small craft technique for the use of two
    slide rules in solving an altitude of the sun by formula:
    
    Hc = INV SIN of COS lat COS dec COS t +/- SIN lat SIN dec
    
    A.   Predetermine product of SIN assumed nearest whole latitude and
    SIN declination for nearest hour (commit to memory or recorded on
    paper). This product should be good for an hour of sun CN.
    (declination changing slowly)
    
    Slide Rule #1
    
    Preset to the product of COS assumed nearest whole latitude and COS
    declination for nearest whole hour of UT/GMT. This preset should be
    good for an hour of sun CN also due to the slow change of declination.
    The total COS product of the equation can be performed without further
    movement of the slide for an hour of selected assumed longitude
    meridian angles.
    
    B.   Sum predetermined SIN product with the COS  product of slide rule
    #1
    
    Slide Rule #2
    
    To be  used to determine the INV SIN of sum to find Hc (20" slide rule
    with magnifier recommended for best results)
    
    Slide rule #1 remains preset as before which leaves slide rule #2
    available for solving azimuth.
    
    
    
    --~--~---------~--~----~------------~-------~--~----~
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---
    
    

       
    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