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    Re: Silicon Sea: Leg 79
    From: Michael Wescott
    Date: 2001 Sep 28, 12:16 PM

    > > TC 270.0d, Speed 10.0 Kts, Current Drift 1.0 Kts, Set 280.0d. Var
    > 2.0dE,
    > > Dev 1.5dE.
    > >
    > > 4)  What is the Compass Course(CC)/Course-to-Steer to MOP1(03d 00.0'N
    > >     110d 00.0'W) from the FIX position?
    > > --  -----------------------------------------------------------------
    >
    > From-   3d 28' N         97d 18' W
    > To:     3d  0' N        110d 00' W
    >        ----------------------------
    >     dLat = 28' S  dLon = 12d 42' W = 762' W
    >
    > Taking departure = dLon, and using a rule of thumb that
    > sin(x degrees) = tan(x degrees) = x/60 for small angles,
    > our true course is 60*28/762 = 2.2 degrees south of due west.
    > The current sets us 1.0*sin(7.8d)=.13nm to the left each hour,
    
    Nope, currents sets us 1.0*sin(12.2)=.21 nm to the *right*.
    
    > during which we travel 11 miles, so we need to adjust course
    > to the right 60*.13/11 = 0.7 degrees.  Adding it all up,
    
    To the *left* 60*.21/11 = 1.1 degrees.
    
    > CCTS = TC + current + var + dev
    > CCTS = 270 - 2.2 + 0.7 - 2.0 - 1.5 = 265d
    
    CCTS = 270 - 2.2 - 1.1 - 2.0 - 1.5 = 263.2 (very close for all the
    approximations).
    
    --
            Mike Wescott
            Wescott_Mike{at}EMC.COM
    

       
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