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    Re: Multiple LOP using one sun sight
    From: Marcel Tschudin
    Date: 2005 Aug 23, 14:58 +0300

    >> From T. Shanklin
    >>   Also, I've been trying to practice with the 2102-D starfinder lately-
    >> I've
    >> been having a real hard time having the calculated azimuths (as per 2102)
    >> correspond with the actual azimuth.  Maybe it's just my compass, but I
    >> always seem to be fairly far off (up to 20 degrees), even when I have the
    >> correct star.  I have been adjusting for local declination (true N to
    >> magnetic N).  Any tips?
    Reply from Peter Fogg
    > Sure you're not adding instead of taking away, or vice-versa, your
    > magnetic
    > variation? 20 degrees is a lot of deviation, or local error, but the
    > presence of magnets (eg, sound speakers) in the vicinity can do this.
    > Someone I know had a similar problem that was solved by removing the knife
    > in its sheath from the pillar holding the cockpit compass.
    
    As Peter Fogg mentions, 20 degrees is a lot. In order to find out how much
    error the boat contributes, I would suggest you compare compass readings
    with known azimuth values (calculated from a map using your known position
    and known reference points). Regarding declination, be aware that in North
    America this value does change within relatively short distances, this is
    due to the fact, that the magnetic pole is located at the moment in the
    north of Canada.
    
    Here some links which might help:
    
    On this Web page you can calculate the declination for a given location and
    date:
    
    http://www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcDeclination;jsessionid=1C65BD5E560ACC6FA87F80EB015296E4
    
    Magnetic compass adjuster (30 days free tryal)
    http://www.pangolin.co.nz/c-swing.php
    
    Or the two general pages with a lot of links in it
    http://www.geocities.com/magnetic_declination/#COMPENSATE
    http://www.ngdc.noaa.gov/seg/geomag/faqgeom.shtml
    
    Hope it helps
    
    Marcel
    
    
    

       
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