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    Re: Relative plotting vs Geographical plotting
    From: Geoffrey Kolbe
    Date: 2002 Jan 12, 1:26 AM

    George Huxtable [mailto:george{at}HUXTABLE.U-NET.COM] said:
    >
    > I don't think Peter Smith's solution can possibly be correct: commonsense
    > tells me so. We have two ships travelling in nearly the same direction,
    and
    > the second ship is slowly overtaking the first. In that case, the speed of
    > the overtaking ship must be greater than that of the ship being overtaken.
    
    Peter Smith said:
    
    >Hmmm. I'm not sure from the above who's the "second ship" and who's
    >the "first ship". The target is ahead of us and to Port (bearing 322d).
    >The bearing is constant, so we are converging. Since the target is
    >ahead and the range is decreasing, we must be overtaking the target.
    
    I am a little confused. George says that the target ship is overtaking the
    "own" ship, Peter thinks that the target ship is the one being overtaken.
    But the relative bearing is constant at 322 degrees, so (as George says)
    the two ships are in fact on collision courses. In this context, what does
    "overtaking" mean, as neither ship is "pulling ahead" of the other?
    
    For what it is worth, I plotted the courses out on a piece of squared paper
    (anything will do) and got course 155 degrees, speed 10.9 knots for the
    target ship, which agrees with Peter. If both ships remain on their present
    courses, they will collide at 0938.
    
    
    Yours aye,
    
    Geoffrey Kolbe.
    

       
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