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: Impressed with the Raft Book
    From: Mike Boersma
    Date: 2010 Feb 1, 05:32 -0800

    There is a quote in Duttons that Captain Weems made 10 horizon sights on six occasions with an average error of 2 miles and a maximum error of 4 miles. Duttons does not explain how he did this. He must have had extremely good conditions.

    Gatty speaks of accuracy of between 6-10 miles with his tables. Again, under ideal conditions, he probably is correct. I was impressed that the theory gave ball park accuracy to begin with.

    Under real world conditions (obscured horizons, uncompensated refraction error, non-standard atmospheric conditions, etc.) I would think that at best a novice navigator using nothing but a watch and Gatty's tables could get results within 30 miles for latitude under ideal conditions by timing the length of day.

    The only advantage that this method has is that it can be done without instruments. This method should only be a backup to some more accurate method of determining latitude.
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    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