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: How Many Chronometers?
    From: Henry Halboth
    Date: 2009 May 6, 18:00 -0700
    Astronomical observations with a reliable, error free or error corrected, sextant, quintant, or even octant can be remarkably accurate as respects the determination of Chronometer Error, even on a good sea horizon. In my personal experience, I believe the Lunar Distance to be the more difficult observation as it probably requires the greater obsevational ability, but both the Equal Altitudes and Time Sight solutions are well within the capability of the average observer and will produce satisfactory results on a good sea horizon and excellent results with a mercury artificial horizon. The proof is in the trying.



    --- On Wed, 5/6/09, enoid@northwestel.net <enoid@northwestel.net> wrote:

    From: enoid@northwestel.net <enoid@northwestel.net>
    Subject: [NavList 8165] Re: How Many Chronometers?
    To: NavList@fer3.com
    Date: Wednesday, May 6, 2009, 5:13 PM

    I'd like to chime in here (no pun intended)

    The methods described by the group seem to be dependant upon taking observations with relatively course nautical instruments. Seems to me unless you are one hell of a superb navigator, you would not be able to discern what is a clock error vs. what is an observation error. Determining your longitude and/or time via lunar distances for example, is only as accurate as the observer and his sextant and with so many variables (temperature, observer error, instrument error, refraction etc.) is it realistic for one to expect that he can determine chronometer error by this means? Unless your chronometer is out by hours.

    I may be way off base here so feel free to correct me.


    ----- Original Message -----
    From: Brad Morris <bmorris@tactronics.com>
    Date: Wednesday, May 6, 2009 4:57 pm
    Subject: [NavList 8164] Re: How Many Chronometers?

    > Hi Jim
    > True, it is a clock with a known rate, but the rate can change!
    > Let us assume for a moment a mechanical chronometer.  As the
    > lubrication ages, the rate changes.  In the literature, you can
    > see instances of a sea rate and a land rate.  Temperature can also
    > affect the rate.  For an electronic (quartz) chronometer, a very
    > run down battery will have a slowing rate.
    > For any of these items, how would you know the rate was changing? 
    > Greg suggested comparison to other chronometers.  Henry and I have
    > suggested celestial observations with a known longitude.
    > We can even see Worsley and Shackleton, attempting to correct
    > their chronometers by lunar occultations, when stuck on the ice in
    > the Weddell Sea.
    > Best Regards
    > Brad
    > -----Original Message-----
    > From: NavList@fer3.com [NavList@fer3.com] On
    > Behalf Of James N Wilson
    > Sent: Wednesday, May 06, 2009 4:39 PM
    > To: NavList@fer3.com
    > Subject: [NavList 8163] Re: How Many Chronometers?
    > Brad:
    > I guess I thought that a chronometer was defined as a clock with a
    > constant rate of read, copy or
    > disseminate this electronic mail (or any attachments) or any part
    > thereof. If you have received this electronic mail (and any
    > attachments) in error, please call us immediately and send written
    > confirmation that same has been deleted from your system. Thank you."
    > >

    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@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)