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: Lunars for dummies like me
    From: Jim Thompson
    Date: 2004 Sep 24, 08:30 -0300

    > -----Original Message-----
    > From: Navigation Mailing List on Behalf Of Jan Kalivoda
    > The ship clock was regulated according to time sights of Sun and
    > trusted between on sailing ships, at least if there wasn't any
    > chronometer onboard. So the application of the Equation of Time
    > wasn't important at sea without a chronometer, at least before
    > 1833 (or 1832/34?), when GAT was superseded by GMT as the
    > argument of the Nautical Almanac. This was caused by growing
    > numbers of chronometers at sea, of course. Previously even the
    > lunars were given in GAT.
    Very helpful insights, Jan.  (And thank you for yours also, George).
    Can anyone expand on the process that crews followed to keep their ship's
    clock updated from time sights without a chronometer on board?  I understand
    how the time sight, taken when the sun was nearly due east or west, gave
    them an estimate of sun's LHA and therefore LAT.  And I understand how they
    could compare that to their LAN estimate from their noon sun sight.  But how
    did they convert the difference between LAN and LAT to a time for their
    ship's clock?  Was it is as obvious as it seems to be -- simply adding the
    number of hours and minutes of LAT to 1200, and then adjusting the hands of
    the clock to match that time?
    Slithery stuff indeed.

    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