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    Re: Newbie - Variation Question
    From: Yves Arrouye
    Date: 2002 Feb 13, 20:59 -0800

    > If the "compass var." setting on the instrument (or in French, "deviation
    > compas") is at zero degrees (as is originally preset when you take it new
    > out of its box), then as you would expect, the magnetic course to that
    > waypoint is zero degrees.
    >
    > Now if you change "compass var." to 10W (the sign is set as E or W, not +
    > or -) the indicated compass course to the North pole waypoint becomes
    > 350deg, not 10 deg as it should be. The only way to obtain the correct
    > magnetic course that you need (010 deg.) is to take the variation given on
    > a chart (say 10 deg West) and enter it as "10E".
    >
    > There's no need to go into what you add or subtract from what to get what.
    > The behaviour is clearly WRONG. There is a serious blunder in the
    > programming of that instrument, which will result in magnetic courses in
    > error by twice the variation. As far as I can tell, the makers are
    > attempting to deny the blunder (as I have found out in discussion with
    > their distributor). I have emailed M.  L. Moreau at
    > lmoreau{at}thalesnavigation.com and await his reply.
    >
    > The manual is completely silent on this matter, except for the following
    > words-
    > "BRG = Bearing from your position to the position of the destination
    > waypoint, in degrees. This bearing relates to true North but an off-set to
    > compensate for local compass variation may be entered if required."
    >
    > Taken with the label "compass var.", would the user expect to enter
    > against
    > that label the compass variation from the chart, or a variation in the
    > opposite sense?
    
    I think whoever did that programming thought of the "variation to get to the
    compass heading" instead of "variation *of* the compass heading." As you
    say, clearly wrong and misleading.
    
    YA
    
    
    

       
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