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: Slocum's lunars
    From: Fred Hebard
    Date: 2003 Dec 23, 11:24 -0500

    I agree with the conclusion, given the premise.  The premise has not
    been established with certainty however.
    On Dec 23, 2003, at 10:47 AM, Steven Wepster wrote:
    > Hi all,
    > Concerning the errors that Slocum would have discovered, let me add
    > this.
    > An article appeared in the 'Navigation'  journal (Vol. 44 no. 1, 1997)
    > in which the author (S.Y. van der Werff) discusses lunar distances and
    > particularly the lunar distance observation of Joshua Slocum on june
    > 16, 1896, shortly before his landfall on Nukahiva. He comes up with a
    > completely different kind of error that Slocum discovered and
    > corrected.
    > Van der Werff notes that the Nautical Alamanc uses the astronomical
    > date convention, i.e., a new day begins at noon, not at midnight. The
    > layout of the lunar distance tables is such that one can not be
    > mistaken by 12 hours, but not so the right ascension and declination
    > tables. Van der Werff's suggestion is that Slocum accidentally took
    > the RA/Dec values for a time 12 hours off (12 h too late, actually).
    > Slocum's 'discovery', then, was that the tables were 12 hours off.
    > If that was indeed the error that Slocum made, I conclude that he was
    > _very_ unfamiliar with the time convention in the almanac. He would
    > have had no earlier occasion to stumble over this difference of 12
    > hours, or at least no such occasion had occured in the voyage with
    > 'Spray' and for quite some time before. It would imply that usually he
    > took from the almanac only data that were forgiving of such an error:
    > declinations, but no right ascensions. I would conclude that, on the
    > large, Slocum's only means of astronomical navigation was by meridian
    > altitudes.
    > Does this appear as a likely scenario to list members?

    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