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    Leg 56 Question # 3
    From: Millard Kirk
    Date: 1999 Jul 17, 8:42 AM

    Nav List,
            When I joined this list I did the problem by graphic methods when possible
    and work the DR's by using formulas from my "Calculator Afloat" book, now
    out of print.  I chose to purchase a Celesticomp V calculator because it is
    dedicated to the navigational problems.  It works well, but is unforgiving
    if you input data in the wrong format.
            Now to question # 3 Leg 56:
            I may be missing something so feel free to enlighten me.  As I look at
    question # 3  I feel there is not enough data to work the problem.  Buffeted
    for two days;  we were buffeted for two days, what was our average speed for
    those two days?  It must have dropped and would have been recorded on an
    hourly basis in keeping  the log as the rules of DR require.  I think there
    are six of the rules for log entries for  DR.  Entries are made (1) A DR
    position will be plotted every hour on the hour, (2) A DR position well be
    plotted at the time of every course changes, (3)  A DR position will be
    plotted at every speed changes , etc.
            Starting at 11:50:00 UTC on the 20/03/1999 at position 42d 39.8'S  98d
    51.5'W, var 30d E dev 3d W and traveling at a speed of 10.3 Kts. we are to
    calculate the DR  for a time of 18:48:23 ZT @ 23/03/1999.   By my
    calculation for the time it is 3 days 13 hrs 58 min 23 sec or 85hr 59min 23
    sec.  When I calculate the DR from these parameters I get a DR of  55d
    38.7'S   88d 04.2' W.
            That is the reason I asked in a previous post what did buffet mean, our
    speed must have dropped considerable, and would have given us a much lower
    average speed for the 895.8 nm miles traveled in those three days, the
    distance from our starting point to the DR.  To travel the 895.8 nm, by my
    calculations the speed would still around 10.3 kts, and that gives me the DR
    of 55d 38.7' S   88d 04.2'  W.
            I could be way off on my thinking, but I can't get to the DR posted by the
    answers for question # 3 from the data presented.  What am I missing????
            Thanks Dan for the problem. The thing I have learned on this list have come
    in mighty handily on my adventures.  I have been on an adventure and have
    not been participating in the problem for a while.
    Learning the Hard Way!!
    Millard Kirk KB8YQO       | mailto:mkirk@marshall.edu
    116 Lewis Ave                    | http://webpages.marshall.edu/~mkirk/
    Barboursville, WV               | A West Virginia Blue Water Sailor
    25504                                 | Phone: (304) 736-6544
                                               | First United Methodist Church,
    Barboursville, WV
                                               | Homepage

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