Quote:
Originally Posted by wiredantz
My manual says I have to change the gps from true north to magnetic north so I'll try that
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The north pole is further "east" than "true" north (straight up) by 13 degrees or so in this region. So when your compass reads N (0deg) your true heading is 13. I always set my GPS to magnetic to keep it simple.
Other factors include wind and current. GPS only shows your track over the ground, while your compass shows your actual magnetic heading. So its not uncommon to see a variance there unless it is dead calm.
Finally, magnetic deviation and interference (sonar and power cables, other magnetic structures in the area, for example) can cause a variance.
But if you keep your GPS in magnetic mode it shouldn't vary more than 5-10 degrees in most circumstances, close enough for a kayak.