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    Silicon Sea: Leg 71
    From: Dan Hogan
    Date: 2001 May 09, 7:49 AM

    Chart(s): Plotting Sheets
    Sight Reduction and
    Dead-Reckoning problem     Leg 71  050801   Test your knowledge!
    ----------------------     ------  ------   --------------------
    At 18:27:00ZT @ 29/05/2001 we took a departure position of (13d 25.6'N
    61d 30.1'W) as we passed between the Lessor Antilles islands of St, Lucia and
    St. Vincent. We are bound for, Mid Ocean Point(MOP1)(12d 30.0'N  70d 00.0'W),
    in water of more than 1000 mtrs North of Aruba. This is to avoid unfavorable
    currents along the coast.
    Dev 1.5dE, Var 12dW. Speed is 8.7 Kts, Current Drift 0.7Kts, Set 270.0d.
    TC 263.7d.
    1)  At the log reading of 89.6Nmi, what is the DR position?
    --  -------------------------------------------------------
    2)  At the DR position what is the celestial phenomena that is starting
        at this DR Zone Time(ZT)?
    --  -------------------------------------------------------------------
    NOTE: Sextant Index correction is on the arc 1.5d.
    We then take the following sights:
        Body        UT          Hs
        Fomalhaut   08:50:10    40d 54.7'
        Polaris     08:50:55    13d 17.3'
        Deneb       08:51:05    56d 56.3'
        Mars        08:52:03    25d 35.0'
        Venus       08:53:22    28d 13.8'
        Vega        08:53:45    45d 55.6'
    3)  What is the FIX position?
    --  -------------------------
    The navigator has been examining nautical chart INT 400. It shows an area
    labeled the Aruba Gap (13d 50.0'N  70d 00.0'W) with a favorable current of
    1.15 Kts. He decides to make for this waypoint. Var 12dW, Dev 1dE.
    Current Set 275d Drift 0.8 Kts. Speed 9.3 Kts.
    4)   What is the TC and Dist from our FIX to the Aruba Gap
         (13d 50.0'N  70d 00.0'W)
    --  ------------------------------------------------------
    5)  What is the Compass Course(CC)/Course-to-Steer for Aruba Gap?
    --  -------------------------------------------------------------
    6)  What is the time enroute to Aruba Gap?
    --  --------------------------------------
    7)  What is the anticipated Speed Made Good(SMG) to Aruba Gap?
    --  ----------------------------------------------------------
    Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 9 Feet, Index correction
    -1.5', 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(Dead-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
            John Simmonds-   johnsimmo@dingoblue.net.au
            David Weilacher- daveweilacher@earthlink.net
            Tony Cappiello-  cappiello@kearfott.com
            Frank Norris-    NORRIS_FRANKLIN_H@LILLY.COM
            Dan Hogan    -   dhhogan@veriomail.com
    Dan Hogan

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