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    Silicon Sea: Leg31
    From: Dan Hogan
    Date: 1997 Jul 17, 1:35 AM

    Sight Reduction and
    Dead-Reckoning problem     Leg 31  071797   Test your knowledge!
    ----------------------     ------  ------   --------------------
    
    We are at the waypoint at (16d 00.0N 54d 30.0'E) on GMT Date 28/06/1996
    {at} 07:05:1996 we set a course for Cape Leeuwin(34d 15.0'S  115d 06.0'E).
    
    1) What is the TC and Dist to Cape Leeuwin?
    -- ----------------------------------------
    
    From the WP we travel until evening twilight. Until three unidentified
    stars are seen through breaks in the clouds. We take an SR and the bearing to
    each body with the ships compass.
    
    Speed 9.3 Kts. Var 3dW, Dev 2dW. Drift 9, Set 135. The sky has been solid
    overcast, and seas lumpy. Winds increasing.
    
    2) What is the Estimated Position(EP) at the ZT of the sight of the
       first body?
    -- ----------------------------------------------------------------
    
        Body/GMT       Hs            Compass Bearing          Brightness
    
        1 15:16:24     32d 42.1'       139.6d                   Mid-bright
        2 15:20:30     21d 50.2'        58.4d                   Brightest
        3 15:25:10     36d 05.9'       279.9d                   Dimmer
    
    3) What are the Names of the three bodies shot?
       What is the calculated Zn of each body?
    --  -------------------------------------------
    
    4)  What is the FIX position?
    --  -------------------------
    
    We use Body #1, since it was the plotted time body.
    
    5)  What is the total compass error?
        Does the total error match the known variation and deviation?
    --  -------------------------------------------------------------
    
    The ocean is rough with cross seas. Winds have increased to Force 5 at 40d.
    Near midnight green sea breaks over the bow. When they clear we see that
    the starboard water cans have been washed away. We have lost a third of
    our water supply.
    
    The nearest land with supply capabilities on our track is the Maldive
    Islands. We plot a course to a waypoint near Male' Island(04d 30.0'N
    73d 00.0'E)
    
    6)  What is the 24:00:00 Estimated Position(EP)?
    --  --------------------------------------------
    
    Checking the Pilot Chart we find that the current is indicated as
    Drift 9Kts {at} Set 76d for the direction toward the Maldive Islands. Var 3dW,
    Dev2dW. Because of heavy seas our speed is reduced to 8 Kts.
    
    7)  What is the TC and Dist to The Male' Waypoint?
    --  ----------------------------------------------
    
    8)  What is the Compass Course to steer?
    --  ------------------------------------
    
    Note:
    Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 8 Feet, Index correction -.2', Time
    hh:mm:ss in UTC/GMT. Silicon Sea is a medium displacement sailing vessel, 40
    Feet LOA. 38 Feet LWL; Cutter rigged. Looks a lot like a Mason. Can tack to
    45d. Dist to Horizon: Nmi = SQRT HE{at}mtrs x 2.07; Nmi = SQRT HE{at}ft x
    1.17. Water Tank = 60 gal(Imp.). Fuel Tanks = 90 gal (Imp.). Fuel
    consumption .450 gal/Hr at 8.3 Kts.
    
    PLEASE respond with your results and thinking on these exercises to the
    NAVIGATION list at large. If you have questions or problems, A lot of folks
    on the list are knowledgeable and willing to help. Any questions or doubtful
    areas will be responded to promptly. Let us hear from you soon!
    
    Good Navigating!
    
       -=The Navgation List Working Group=-
    
            Peter Smith  - psmith{at}wellspring.us.dg.com
            Ron Legere   - ronald.legere{at}yale.edu
            Tony Severdia- anthonys{at}ix.netcom.com
            Wes Muffin   - wmurfin{at}onslowonline.net (Cartographer)
            John Simmonds- mobi{at}netconnect.com.au
            Dan Hogan    - dhhogan{at}lightside.com
    
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