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: USCG exam memories
    From: Greg Rudzinski
    Date: 2010 Dec 25, 12:03 -0800

    The strangest Nav exam question that I can remember involved the ex-meridian. This required table 29 and 30 lookups in Bowditch to correct an observed altitude near meridional passage to get the actual meridian altitude (Bowditch calls this reduction to meridian). Never used this method outside the exam room and felt that it was a curious antiquated celestial technique. Table 29 is entered with the nearest whole latitude and declination to get the one minute altitude rate of change(a). The one minute rate of change(a) and meridian angle(t) or minutes to transit are used to enter table 30 for the correction in minutes of arc to be added to the observation(Ho) to get an upper transit altitude. Table 30 covers observations made within 28 minutes of time either side of meridional passage.

    Greg Rudzinski
    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