Map Reading Techniques (Tutorial)

Share navigation tips, discuss map-reading, compass use etc.

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Nik - KOTM
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#16 Post by Nik - KOTM » Mon Oct 29, 2007 6:47 am

To compound matters, the earth's magnetic field doesn't run straight north-south, either. In some parts of the world the deviance can be 30 degrees! Any decent topographical map will tell you the magnetic deviation, the year the map was printed and the annual change in deviation
I'll give you another one too - for some reason the Earths Magnetic poles will flip over - South becomes North and North becomes South - but fortunately this is highly unlikely to affect us in our life time
Nik 245 to go


Add degrees or take them away....which one is it?

#17 Post by martynj » Sun Feb 22, 2009 7:11 pm

Hi All,

I was told an easy way to remember whether to add or subtract the deviation by a yatchy friend:

If your taking a bearing by sight to transfer to the map - take the bearing, then go down to the map (or chart ;)), down means less so take the deviation away. If your taking a bearing from the map to sight, up from the map so add the deviation on.

Hope this helps a little.


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#18 Post by foxy » Sun Feb 22, 2009 8:23 pm

Similar to how I teach it - little world (map) to big world (ground) -add, and vice versa :wink:

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