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Magnetic Or True North?


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When using a gps for geochaching, should the gps be set for magnetic north or true north? It seems to make sense to me to have it set for magnetic north as your compass always will point to magnetic north, then you would not have to adjust for declination.

 

My next assumption would be to change gps to true north when using in conjunction with compass and topo map.

 

I would apprectiate comments and advice.

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;) Mines set for true and we seem to be right on with coords given when finding caches. But good ? Coords are given based on Sats positions around Earth not mag poles. When useing compass, I use "map go to" function and compass then locks to caches coords and points to position of cache (true or mag doesn't matter).
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In most places it doesn't matter. There are places in the world where it does, because the magnetic declination can be well over 30 degrees, but I don't know of anywhere in the lower 48 states of the US where that's the case. I generally keep mine set to true, because offsets are usually (but not always) given as true, and it's usually less trouble not having to switch. For finding a cache with the coordinates already in the GPS, I don't see any difference. I usually can't follow a heading very closely through the woods anyway, and once I get very close the position error is greater than the declination angle anyway.

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Just a quick additional note.... (from a guy who navigates for a living)

 

The farther North and West you get in North America (at least till 65 or so north) the greater the difference between magnetic and true north.

 

In the area of Calgary Alberta (Great Falls Montana) the difference is approx 25 degrees, while say Toronto Ontario (Buffalo NY) is around 5 degrees...

 

Most people relate to true north naturally, as it just makes more sense, SOOOO I would suggest setting things up for true and avoiding any confusion....

 

Cheers

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It depends on several factors.

 

If you're going to pull out a magnetic compass at any point and you want to match - I'd set it to magnetic north. If you're only using maps and your GPS, it doesn't matter. Whether you set the GPS to magnetic or true north, it will still point you in the direction of the cache.

 

It also depends on where you are:

WMM-00D.gif

mdec.jpg

 

Here in the Chicago, Illinois area, we're only between 1° and 2°, so the difference is insignificant. If I were hiking in the Seattle area where the declination is 20°, that's pretty significant.

 

There have been many times where the GPS will be jumping around in direction. When that happens, I look at my bearing on the GPS, pull out my trust Silva, shoot a bearing and follow it. If my GPS were set to true north in Washington, and I tried that, I'd be off by quite a bit.

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Unless you're doing a cache that requires you to follow a certain heading for a certain distance, it really doesn't matter. If you ARE doing a cache like that, the cache page should tell you which to use.

Exactly.

 

It was 3 years before I even knew what my GPS was set too, let alone that it had a setting on that I could change. It points at the cache and that's all I need.

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