Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: chart scale information on charts...
    From: Rodney Myrvaagnes
    Date: 2000 Apr 04, 9:47 AM

    It tells you the scale at a latitude that shows on the particular chart. The 
    Mercator distortion can be measurable near the top and
    bottom of small-scale Mercator charts, relative to the latitude of the scale.
    For example, I am looking at 13324, "Tibbet Narrows to Schoodic Island"
    Scale is 1:40,000 at 44-28 north. That is pretty close to the middle of the 
    chart, which extends from 44-15 to a little more than 44-
    Oblateness error would never be big enough to measure withing any reasonable 
    Mercator chart. Other projections are used for
    long-distance charts.
    On Tue, 4 Apr 2000 15:51:40 +0200, Russell Sher wrote:
    >I have a small question about the chart scale as displayed on mercator
    >Normally the scale on the chart is displayed as that scale given according
    >to a particular latitude for example
    >1: 750 000 (at 34 deg 00' S), thus implying that the scale is calculated for
    >the length of latitude at the given value (in this case 34 deg 00').
    >My question is - Is the scale stated in this way due to the mercator
    >distortion as one travels away from the equator (due to the nature of the
    >projection), or is the scale stated in this way due to the (slight) change
    >in the value of a minute of latitude due to the oblate shape of the earth?
    Rodney Myrvaagnes                   J36 Gjo/a
    Senior Editor           Electronic Products
    My oyster knife is Y2K compliant

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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