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    Silicon Sea: Leg 90
    From: Dan Hogan
    Date: 2004 Mar 31, 09:50 -0800

    Chart(s): Plotting Sheet
    Sight Reduction and
    Dead-Reckoning problem     Leg 90  033104   Test your knowledge!
    --------------------------     -------   --------   --------------------
    At a DR position of (38d 18.8'N  132d 44.2'W), @ 22:57:11UT 15/09/2002 a
    in wind permits us to break off of the tack we are on and set a course for
    MOP4(34d 20.0'N  120d 33.0'W) the entrance to the Santa Barbara Channel in
    Southern California.
    Current Drift 0.6 Kts, Set 170d. Var 15dE, Dev 2.0dW. Speed 10.5 Kts.
    1)  What is the CC/Course-to-Steer and the Distance to MOP4
     (34d 20.0'N  120d 33.0')?
    --  --------------------------------------------------------
    At 15:22:55UT @ 16/09/2002 at DR position (37d 13.7'N  129d 19.3W)) we
    a SUN sight.
     SUN LL
        Hs= 11d 32.4'
     GHA = 52d 01.2'  Dec = 02d 32.8'
    2)  What is the Azimuth of the SUN?
    --  -------------------------------
    At 02:11:20UT @ 17/09/2002 we take a sight, of the only body visible through
    the clouds:
    TC 112.0d, Speed 10.5 Kts, Var 15dE, Dev 2dW.
     MOON LL
        Hs: 15d 38.5'
     GHA = 81d 34.8'  Dec = 23d 07.7'S
    3)  What is the DR Position for the MOON sight?
    --  -------------------------------------------
    4)  What is the Running FIX(RFIX) at the time of the MOON Sight Reduction?
    --  ----------------------------------------------------------------------
    5)  What is the reliability error of this RFIX? Small or OK.
    --  --------------------------------------------------------
    Var 14dE, Dev 2.0dW. Current Set 185d, Drift 0.3 Kts. Speed 10 Kts.
    6)  What is the CC and Dist to MOP4 (34d 20.0'N  120d 33.0')?
    --  ---------------------------------------------------------
    As we approach the coast line the weather turns hazy. We are on the look
    out for
    Mt. Tranquillon, 658 mtrs in height, it is the highest peak near the
    entrance to
    the Santa Barbara Channel near Pt. Conception.
    7)  At what distance should Mt. Tranquillon be visible, weather permitting,
        above the horizon?
    --  -----------------------------------------------------------------------
    Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 9 Feet, Index correction
    -2.5', Time hh:mm:ss in UT,unless otherwise stated. Silicon
    Sea II is a 34,000 lb(15.40t) displacement sailing vessel, 48' 3"
    (14.70m) LOA. 39' (12.00m) LWL; Cutter rigged. Can tack to 45d.
    Water Tanks = 220 gal(1000 ltrs). Fuel Tanks = 155 gal(700 ltrs).
    Fuel consumption .675 gal/Hr at 8.5 Kts. DR(Ded-Reckoning)=position
    by sailings, EP(Estimated Position)=DR+current affect. Dist to
    Horizon: Nmi = SQRT HE@mtrs x 2.07; Nmi = SQRT HE@ft x 1.17.
    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 Navigation List Working Group=-
            Peter Smith -  Smith_Peter@emc.com
            Federico  Rossi - fedeastro.rossi@libero.it
            Dan Hogan - dhhogan1@earthlink.net

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