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: Coastal Plotting Sheets
    From: Bill B
    Date: 2007 Apr 01, 19:19 -0400

    
    
    George Wrote:
    >
    > Yes, to fix by horizontal sextant angles you need to have three marks on
    > shore, and in the right sort of geometrical alignment to give a good cut
    > between the circles, as against only two marks for compass bearings. But in
    > terms of the precision of the result, there's really no contest.
    
    I'm in full agreement, assuming the objects are carefully chosen.
    
    Regarding variation and deviation, I go online at the beginning of the
    season and obtain mid-season variation and update the compass roses on my
    charts as well as areas I frequently visit.
    
    I have found my hockey-puck compass, in almost all circumstances to exhibit
    no noticeable deviation if I pick a spot on a sailboat (usually coaming)
    away from metal or electrical wiring).
    
    With three objects onshore I take sextant angles between them, and a compass
    bearing to the middle object.  If I draw a line from the center object with
    that bearing corrected to true, and then the observed angles from that
    center line through the objects, I have immediate feedback if my compass
    bearing is off a bit--and in which direction--as the lines from the left and
    right objects will not intersect the center line at the same point.
    
    This method is of course limited by the precision and accuracy of the
    plotting devices/protractor, but I am constantly amazed at the proximity of
    the plot to the GPS position.
    
    Bill
    
    
    
    
    
    --~--~---------~--~----~------------~-------~--~----~
    To post to this group, send email to NavList@fer3.com
    To unsubscribe, send email to 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