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    Re: Newbie - Variation Question
    From: Aubrey O?Callaghan
    Date: 2002 Feb 14, 08:28 -0400

    George,
    No doubt you will notify the RIN, and the Cruising Association.
    Perhaps a letter to the Editor of Yachting World, Yachting Monthly and
    Practical Boat Owner would be useful. These publications are quite widely
    read in Europe. Pierre Boucher might be able to recommend French magazines
    where it should be published, Voiles etc.
    However, I suggest we wait for a reasonable time for M. Moreau to reply
    before sending letters to the Editor. No harm in letting the RIN know though.
    
    Aubrey.
    
    At 19:31 13/02/02, you wrote:
    >My last message crossed with the latest postings from Yves Arrouye and Dave
    >Weilacher.
    >
    >Let me try to simplify the discussion by defining exactly what is observed
    >on this instrument, the GPS receiver by the French firm MLR Electronique,
    >type SP24 and also SP24Y. The firm is now owned by Thales Navigation.
    >
    >First, set up a waypoint at the North Pole and from anywhere on Earth,
    >observe what the receiver gives as the magnetic course to that waypoint.
    >
    >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 the maker's attitude is dangerous, and makes matters worse. Once a
    >user has been alerted to the problem, the danger largely vanishes. But if a
    >user, ignorant of the problem, tries to set magnetic courses, he is likely
    >to find himself in considerable danger.
    >
    >I intend to publicise the matter, and wonder if any listmember can advise
    >me about other navigation mailing lists which do not exclude electronic
    >navigation, and how to join so as to post an appropriate warning message.
    >
    >George Huxtable.
    >
    >
    >------------------------------
    >
    >george---.u-net.com
    >George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    >Tel. 01865 820222 or (int.) +44 1865 820222.
    >------------------------------
    
    
    

       
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