Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Time sight primer
    From: Chris Mitchell
    Date: 2019 Sep 27, 06:27 -0700

    Thanks to everyone who have chimed in on this topic, and provided some clarification to the issue.

    Frank, when I asked "would it be safe to say that this method of finding longitude and local apparent time was replaced with by more modern longitude by chronometer method and UTC?" I should have been more specific. I realize now that there is more than one “version” of a time sight, this method that I have been asking about relies on table XXV in the older versions of Bowditch. The method that I am familiar with uses the formula: cosP = (cosZD – sinLat * sin Dec) / (cos Lat * cos Dec). In the end, both methods accomplish the same thing, I was just wondering if this newer formula method would have superseded the older Bowditch method, however the Bowditch method with its tables would definately be easier if you never had a scientific calculator to comput the formula. Are there any other "versions" of time sights besides the two mentioned perviously (Bowditch tables & formula)? Also, with the implementation of time zones I assume that keeping local apparent time became a thing of the past on ships. The only time I hear it mentioned onboard now is when referencing local apparent noon for a noon sight.

    Chris

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    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