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    Re: Silicon Sea Leg 69: ANSWERS
    From: Michael Wescott
    Date: 2001 Apr 10, 13:52 EDT

    dhhogan{at}XXX.XXX said:
    > On 9 Apr 2001, at 11:43, Michael Wescott wrote:
    > > We continue sailing maintaining the same speed and True Course with an
    > > overcast sky. Then, with the navigator on deck waiting for an opening
    > > for a Sun shot, we see a spot of land on the horizon ahead. It is
    > > 20/05/2000 {at}XXX.XXX >
    > > 3)  What is the DR position?
    > > --  ------------------------ >
    > S = 10.7 C = 288.9 T, >
    >   20/05/2000 12:13:00 ZT = 20/05/2000 16:13:00 UT
    >                           -18/05/2000 22:20:00 UT
    >                          ========================
    >                             1 day     17:53:00
    > or 41.88 hrs >
    > Dist = 41.88 * 10.7 = 448.1 nmi >
    > D.Lat = 448.1 * cos 288.7 = 145.2 = 2d 25.2' >
    > DR Lat = 9d 50.5' + 2d 25.2' = 12d 15.7'
    >  dmp = mp(12d 15.7') - mp(9d 50.5')
    >      = 147.0
    > D.Lo = 147.0 * tan(288.9)
    >      = -429.4
    >      = -7d 09.4
    > DR Lo = -53d  00.0 - 7d 09.4'
    >       = -60d 09.4 >
    > DR  12d 15.7'N    60d 09.4'W >
    > Actually this is too far off to make any sense.
    > We seem to be well past Barbados.
    > It is off. If you are calculating use a Traverse Table interpolation
    > may be accumlating an error.
    Nope. I used meridional parts (that's the mp() function above).
    Going back the the published answers:
    > 1. FIX= 9d 50.0'N  53d 00.2'W
    > 3. DR= 13d 16.4'W  59d 32.3'W
    and working backwards, there was a course change to 298 d (TC) after
    the fix. This makes sense, but it wasn't mentioned in the text of the
    problem and the other course does bring us conveniently south of
    Barbados.
    <PRE>
    --
            Mike Wescott
            Wescott_Mike{at}XXX.XXX
    </PRE>
    

       
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