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True VS Magnetic


2DMO
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Hi,

 

I'm no expert but for what its worth I dont think that it really matters on either case.

Since, when geocashing then the compass will try to point the location you are trying to find - nothing to do with the real or magnetic north.

And when highway traveling all it should change is your map display by few degrees when you have selected "north up" option.

Edited by v2lek
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1. When geochaching which is best;

The only time this is an issue during geocaching, is if you are doing a puzzle or a multi-cache that requires you to project a waypoint. You have to make sure you project using the same orientation that the cache hider used (most hiders will tell you what to use). So, there is no best, but you do have to be aware which to use when projecting waypoints.

 

--Marky

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Two part question:

 

1. When geochaching which is best;

 

2. When highway traveling.

 

Thanks from a rookie

 

In those applications, I agree with those who suggest that it doesn't matter.

 

true v. magnetic north is relevant if you are doing something related to orienteering and using the gps in conjunction with a map and a compass. Even in those applications, I think it is still a matter of personal preference. But, in either case, if you are going to use the gps for that kind of application, you should understand the concept of declination and know the declination angle for the area in which you are working - which you can get from either a topo map or from the gps.

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Absolutely, doesn't matter. Either case.

However...

 

The gps "thinks" in True; for the magnetic setting it uses a declination model for your position to alter the readings (just like it uses UTC for time and offsets that for your time zone), which changes over time. A new model is instituted every ten years (or is it 5).

 

Most maps are in True orientation.

 

Many roads are laid down in True.

 

Certainly if you are using a compass then you must either alter the GPS to Magnetic, or (better yet) alter the compass to your declination for True. An easy task that requires just a small bit of knowledge on using a compass.

 

Guess which I use :laughing:

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Updates for declination models are every five years:

"Models need to be revised at least every five years because of the changing nature of the magnetic field. Existing models forward predict the magnetic field based on the rate of change in the several years preceding the model generation. Since that rate of change itself is changing, to continue to use models beyond 5 years introduces progressively greater errors in the field parameters calculated. "

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