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A go at Silicon Sea: Leg 88

From: Peter Fogg (no email)
Date: Wed Aug 13 2003 - 02:02:38 EDT

  • Next message: David Hoyte: "Navigating Around Hills and Dips in the Ocean"

    > Sight Reduction and
    > Dead-Reckoning problem Leg 88 062503 Test your knowledge!
    > ---------------------- ------ ------ --------------------
    > We are headed for Mid-Ocean Point 1 (MOP1) (40d 00.0'N 155d 00.0'W).
    >
    > On 09/09/2002 @ 03:30:20UT our DR position was(34d 10.4'N 150d 20.2'W.
    > TC 327.4d, Speed 10 Kts, Drift 0.4 Kts, Set 273.0d. Var 15dE, Dev 1dW.
    >
    > 1) After 39Hours, what is the DR position?

       A: DR N39d 40' W154d 42'
    > -- -------------------------------------------------------

    > 2) What is the Zone Time(ZT) and date of this DR position?

              A: 08:30:20ZT on 10 Sep 02
    > -- -------------------------------------------------------
    >
    > Since the sky is a solid overcast, we were not able to take any
    > celestial sights. We decide to alter course for Mid Ocean Point 2
    > (MOP 2) (45d 00.0'N 118d 15.1'W).
    >
    > 3) What is the TC and Dist to MOP 2?

    A: from the DR, 079d TC for 1653nm.via the rhumb line
         via a Great Circle, initial course of 067d for 1634nm.
    > -- ---------------------------------
    >
    > Var 11.0dE, Dev 1.5dW, Current Drift 0.4 Kts, Set 120d. Speed 10 Kts.
    >
    > 4) What is the Compass Course(CC)/Course-to-Steer to MOP 2
    > (45d 00.0'N 118d 15.1'W)?

    A: CC to steer 055.5d
    > -- --------------------------------------------------------
    >
    > On this same day at a DR position of (39d 46.1'N 153d 54.8'W) at
    > 12:12:34ZT we manage a quick sight of the SUN. Var 11.0dE, Dev 1.5dW
    >
    > SUN LL Hs 54d 48.1'
    >
    > 5) What is the Estimated Latitude line of this Sight?

    A: With an azimuth of 180d, and an intercept of 0, the latitude line
    indicated is N39d 46' (to the nearest arc minute)
    > -- ---------------------------------------------------
    >
    > At 05:10:21UT 11/09/2002 we manage a sight of an unknown body through a
    break in the cloud cover.
    >
    > Bearing by Hand Compass 266.4d, appearing to be a magnitude 0.1.
    >
    > Hs 33d 45.0'
    >
    > 6) What is the Name of this Body?

    A: Arcturus Mag 0.2 Azimuth 267d
    > -- -------------------------------
    >
    > Using the earlier SUN sight and this Body sight for a running FIX.
    >
    > 7) What is the Running FIX(RFIX) position?

    A: RFix N40d 03' W151d 59'
    > -- -------------------------------------------------------------


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