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    Re-Issue of Leg 89
    From: Dan Hogan
    Date: 2004 May 8, 13:25 -0700

    Chart(s): Plotting Sheets
    
    Sight Reduction and                           Re-Issue
    Dead-Reckoning problem     Leg 89  050504     Test your knowledge!
    ---------------------------    -------  ---------    ----------------------
    
    On 11/09/2002 at 05:10:21UT we had a Running FIX(RFIX) (39d 43.5'N  151d
    59.1'W).
    
    Due to movement of the Pacific High. With the resulting wind change we have
    altered our course toward Mid-Ocean Point 3(MOP3) at (37d 00.0'N  130d
    00.0'W).
    
    Var 17dE, Dev 2.0dW. Current Drift 0.4 Kts, Set 145d. Speed 10.3 Kts.
    
    1)  What is the TC and Distance to MOP3(37d 00.0'N  130d 00.0'N)?
    --  ------------------------------------------------------------
    
    2)  What is the Compass Course(CC)/Course-to-Steer to MOP3?
    --  -------------------------------------------------------
    
    Due to overcast sky and intermittent rain we are unable to get a FIX for 3
    days
    until a Log reading of 724.4 Nmi since the Running FIX(RFIX) on 11/09/2002.
    At
    05:10:21UT (39d 43.5'N  151d 59.1'W).
    
        Var 17dE, Dev 2.0dW. Speed 10.3 Kts, Set 175.0d, Drift 0.4 Kts
    
    3)   What is the Dead Reckoning(DR) position for the Sight Reduction?
         Use the time of the first SR.
    --   ----------------------------------------------------------------
    Then we manage to get the following round of morning sights on UT
    15/09/2002:
    
     UT    Body   Hs
     03:30:31        Moon LL   25d 59.3'
     03:31:00  Polaris   36d 40.2'
        03:31:12  Vega   83d 07.8'
     03:31:21  Deneb         59d 28.3'
     03:31:55  Altair   52d 57.0'
     03:32:55  Antares   22d 51.9'
    
    Almanac Data
    
    03:30:31  Moon       GHA = 126d 29.5' Dec = 25d 23.2'S
    03:31:00  Polaris  GHA = 007d 46.3' Dec = 89d 16.5'N
    03:31:12  Vega   GHA = 127d 28.3' Dec = 38d 47.4'N
     03:31:21  Deneb   GHA = 096d 22.9' Dec = 15d 17.5'N
     03:31:55  Altair  GHA = 109d 10.8' Dec = 08d 52.5'N
     03:32:15  Antares  GHA = 159d 46.3' Dec = 26d 26.3'S
    
    4)   What is the FIX position?
    --   -------------------------
    
    Examining our charts at the time of the FIX, we select a MOP4 off of Point
    Conception, California near the entrance to the Santa Barbara Channel at
    (34d 20.0'N 120d 33.0'W).
    
    Speed 10.0 Kts. Current Drift 0.6 Kts, Set 170d. Var 15dE, Dev 2.0dW.
    
    5)  What is the Compass Course(CC)/Course-to-Steer?
    --  -----------------------------------------------
    
    Speed 10.0 Kts. Current Drift 0.6 Kts, Set 170d. Var 15dE, Dev 2.0dW.
    
    6)  What is our Estimated Time of Arrival(ETA), Time and Date at MOP4 near
    the
        Santa Barbara Channel MOP4 (34d 20.0'N  120d 33.0'W), UT & ZT?
    --
    ---------------------------------------------------------------------------
    
    As we completed plotting our FIX position, the weather picks up and the
    cloud
    cover increases again. We also run into contrary winds,rain and swells that
    are
    heading our course.
    
    Var 15dE, Dev 2.0dW.
    
    We make the following traverses against the wind.
    
     Compass Course   Distance
    
     86.6d     45 Nmi
     45.0d     55 Nmi
     80.0d     75 Nmi
    
    7)  What is the DR position at the end of the last Tack?
    --  ----------------------------------------------------
    
    8)  What is the TC and Distance to the entrance to the Santa Barbara Channel
        waypoint(34d 20.0'N  120d 33.0'W) from the last DR position?
    --  ------------------------------------------------------------------------
    
    NOTE:
    Lat & Lo = XXd XX.X', Date=DD/MM/YYYY, 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{at}mtrs x 2.07; Nmi = SQRT HE{at}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{at}emc.com
            Federico  Rossi - fedeastro.rossi{at}libero.it
            Dan Hogan - dhhogan1---.net
    
    
    

       
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