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
    Plotting in Magnetic vs True
    From: Lu Abel
    Date: 2009 Aug 04, 16:31 -0700

    My just-posted question on DR plotting actually arose while researching
    a different topic:
    
    When did plotting courses in True (vs Magnetic) become  commonplace?  In
    fact, were courses in a plot originally labeled in True or Magnetic?
    
    I suspect that with the advent of the gyrocompass on ships knowing True
    courses became important.  But there were centuries and centuries of
    navigation before the perfection of the gyrocompass that depended on
    magnetic compasses and it might have made a lot more sense to plot in
    Magnetic.
    
    Of course, if navigators didn't keep a DR plot then the whole True vs
    Magnetic issue becomes more difficult to answer.
    
    The only reference I've found to True vs Magnetic is in browsing through
    NOAA's on-line library of antique charts.  A very few of them have
    courses between prominent objects which are labeled in Magnetic using
    the traditional intercardinal point notation.  An excellent example of
    this is a chart of Woods Hole (although the chart calls itself Woods
    Holl, search for chart 348), a marginal note says "directions not shown
    in brackets are Magnetic, those in brackets are True"   All directions
    are unbracketed.
    
    --~--~---------~--~----~------------~-------~--~----~
    NavList message boards: www.fer3.com/arc
    Or post by email to: 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