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
    Leg 83
    From: Peter Fogg
    Date: 2002 Sep 22, 13:52 +1000

     Q1)          navigator (9ft) to horizon      3.51nm
    Mauna Loa (4169m) to horizon         +133.66 nm
          navigator to top ML on horizon    137.2 nm
    Q2) First calculate TC along rhumb line from (N18d 37'.2  W152d 13'.6)
    to (N19d 30'.0  W155d 36'.0)
           by MP&MD  285.3d
               MP           285.3
           PS (ML)        285.4
           by plot          285d
    Then, by plotting, with fast speed and weak contrary current,  I get CMG
    286d and SMG 9.3k,
           thus TC to steer  284d
    combined error     E   -11d
    CC to steer                273d
    Q3) Time Zone at (W150d +/- 7.5d) is West 10 hours, 10 hours behind UT.
    Q4) traverse from N18d 37'.2   W152d 13'.6    at 290d  for 140 nm.
           MP&MD       N19d 25'.3   W154d 32'.5
            ML              N19d 25'.1   W154d 32'.0
            plot              N19d 24'      W154d 31'.5
        elapsed time is 140 nm / SMG 9.3k = 15h 03m 14s
    Q5) Am a little unsure what is meant to be done here, assume what is
    needed is the CC to steer from
        calculated DR (N19d 25'.3  W154d 32'.5) to DO point (N19d 30'.0
    W154d 41'.6).
        First calculate TC along rhumb line   (distance
              MP&MD 298.6d                           9.8 nm
                MP       298.5                             9.8
             PS(ML)   298.7                             9.8
                plot      299.0d                          12.0 nm - from
    plotted DR)
        Then another vector diagram, this time with current setting to the
    west. TC to steer 300d
    combined error     E   -11d
    CC to steer                289d
        elapsed time is 9.8 nm / SMG 10.5k = 00h 56m 00s
    Q6) rhumbline calculation for distance from (N19d 30'.0  W154d 41'.6)
    to (N19d44'.0  W155d 04'.0)
        by MP&MD  25.3 nm
             MP          25.4
             PS (ML)  25.3
                 plot     25.8
    There is no information on current for this leg so shall assume speed is
    elapsed time is 25.3nm / 10k = 02h 31m 48s
    Q7)     For the ETA at Hilo add the time for each leg to   01:44:36 UT
    on 16/07/2001
    + 15:03:14
    + 00:56:00
    + 02:31:48
    = 20:15:38 UT on 16/07/2001
    = 10:15:38 ZT on 16/07/2001
    MP&MD     Meridional Parts and Meridional Distances
    MP             Meridional Parts
    PS (ML)      Plane Sailing (Middle Latitude)
    As all the distances involved in these rhumb line and traverse
    calculations are fairly short ones in low latitudes there is little
    difference between the different calculations.

    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