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: Using sun compass for calibrating boat compass
    From: Bill B
    Date: 2014 May 08, 13:35 -0400

    On 5/8/2014 9:51 AM, Greg Rudzinski wrote:
    > The way I see this is that Hc is based on an assumed position not the
    > actual position so that the azimuths will differ slightly. Not an issue
    > for the LOP plot. But if an accurate fiber optic gyro were to be checked
    > to it's precision then I would use Ho (not Hc or Hs)to calculate azimuth
    > to the tenth of a degree.
    
    Sean and Greg
    
    Thanks for your input. I do see your points, but still feel like a puppy
    chasing its own tail.
    
    If I understand correctly, in the following formula I would still be
    working from an assumed position as the LHA is derived from the GHA and
    AP longitude, so your caveats are still valid:
    
    Tan Z = sin LHA / ((cos LHA sin lat) - (cos lat tan dec))
    If tan Z is negative, add 180 to Z
    If hour angle is less than 180, add another 180 to Z
    
    If the scenario was similar to Greg's post from the archives, and I was
    working from about a known position (Ho and Hc theoretically equal),
    then the azimuth derived from the Hc or Ho would yield the correct azimuth.
    
    Have I caught up to my tail yet :-)
    

       
    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