› Forums › Geocaching in Wisconsin › Help › Just wondering…

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  • 09/28/2006 at 9:36 pm #1723801
    SLASH354

      I’m fairly new to caching (almost a whole month under my belt). But I was wondering if it makes a difference if my GPSr is set at true north or magnetic north as far as caching goes? Or is that just for mapping? I haven’t had any problems finding the caches I’ve been after, but just wanted to know if having my machine set on one or the other might put me a little closer or if it changes how the machine reads the waypoints.
      Hope to meet some of you on the trails. Thanks for your help, SLASH354

      09/28/2006 at 9:57 pm #1766051
      Jeremy

        @SLASH354 wrote:

        But I was wondering if it makes a difference if my GPSr is set at true north or magnetic north as far as caching goes? Or is that just for mapping? I haven’t had any problems finding the caches I’ve been after, but just wanted to know if having my machine set on one or the other might put me a little closer or if it changes how the machine reads the waypoints.

        This setting (magnetic vs. true north) only affects the “heading” and “bearing” type numbers that the GPS displays (and maybe the north shown on the map for mapping units?). Setting it one way or the other won’t put you closer or farther away from a cache unless you use a compass with your GPS. If this is the case, I would set this to “magnetic north”. (But since the difference between magnetic and true north in WI is so small you’d probably never notice the difference. If you are caching in Maine or Washington this may be a problem.)

        For example, you should be able to set your GPS to show the magnetic bearing to a cache in degrees (example 255 degrees) while going to one. If you pull out your compass and determine a bearing of 255 degrees and follow this bearing exactly, you (theoretically) should step right on top of the cache. Following a compass bearing instead of the “arrow” on your GPS is more accurate (unless of course you have a model with an integrated compass).

        Which brings me to one of my pet peeves… cachers who don’t use or even carry compasses. But I will save that rant for another day. 🙂

        09/29/2006 at 2:00 pm #1766052
        GrouseTales

          I agree with Jeremy. Here in WI there is only a slight difference between Magnetic North and True North. The difference of only a degree or two depending what part of the state you’re in.

          If you were to head out east, or out west, you might see a 18 -20 degree difference between Magnetic North and True North.

          I always use a compass hand in hand with the gps. I let the gps calculate the bearing, then use the compass to point me in the right direction. I always set my gps to display magnetic north.

          Here is a magnetic declination map:

          09/30/2006 at 3:34 am #1766053
          Uncle_Fun

            Compass? What’s a compass? Isn’t that why I bought a GPSr?

            09/30/2006 at 6:26 am #1766054
            Decrepit

              Speaking of the compass… when I took my cousin and his kids caching for the first time I had each of the kids sit with me and punch in coordinates. I figured they had better learn that there is a little bit of work involved before they get to find the treasure. While waiting for big sister Emma to finish punching in the numbers, Nora found the compass I always have in the car. After looking at it for a while, she asked how to tell what time it was with that kind of watch. I explained that it was a compass and that the needle always pointed North. She explained to me that it must be broken because when she turned in circles, it pointed to the letters E, W & S too. 😉 Ah… to be sweet and innocent again.

              09/30/2006 at 6:30 am #1766055
              hogrod

                I also thought that the slight difference here from magnetic to true north wouldn’t make much difference, but it does when projecting waypoints. Those couple degrees really could put you off depending on the distance your going.
                If I have my gps set to magnetic north I get different numbers than if I project with the gps set to true north(both my legendC and 60cx are this way).

                here is a world map with the magnetic declination scale, as you can see there are lots of places that a compass will be off by quite a bit.

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