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hambonesbar

True North Or Magnetic North?

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:unsure:

I am new to geocaching. I have a garmin etrex legend. very cool device.

I have looked for my first cache twice and have not found it. but I will keep looking.

I think it is operator error.

Legend has a setting for north, true, magnetic, grid or user.

which one is best?

are there any other setting I should set to help me navigate.

the manual is ok but does not make recommendations.

 

thanks for all the great info.

 

ali

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The settings for true, magnetic, etc. make no difference for the vast majority of users. Some multi caches may tell you to "project" a waypoint to the next stage (e.g., "go 2256 feet at a heading of 317°"). Then you would need to know if the bearing the cache gives you is true 317° or magnetic north 317°. Set it to true and forget it unless you cache with a magnetic compass.

 

The two most important settings (and the Legend comes this way from the factory) is to have the datum set to WSG84, and to have the format set to hddd mm.mmm (hemisphere, degrees, minutes.decimal minutes). If you have those set right, the Legend should get you to with 20 feet or so of the cache every time. From there, you just have to put down the GPSr and say, "Now where would I hide this thing?"

 

You may want to check out

 

Thot's Beginner's Guide

Markwell's Update to the FAQ and

CyBret's Geocacher University.

 

Lot's of great advice there for beginners.

 

Welcome to the recreational activity/sport/hobby!

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I prefer true north but I live in an area that a road map is all you need to get around. You might get lost in five miles of corn but if you just keep walking the row you'll be fine.

 

Did you pick a cache that is fairly low in difficulty? Has it been found recently?

 

edit: Sputnik 57 has the best suggestions

Edited by BlueDeuce

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Legend has a setting for north, true, magnetic, grid or user.

which one is best?

You will get different opinions on this. If you use maps a lot you may want to set it to True North, but I only use it with a compass and compasses are Magnetic North so I leave it set on Magnetic North.

 

Occasionally a cache will specify you use True North for this or that. In this case you will have to change it for that cache. I always change it back to Magnetic immediately so I won't forget which I'm using.

 

There's also a difference of opinion on which to use if a cache requires one or the other without specifying. Technically/officially if it is not specified it is supposed to mean True, but I believe if someone fails to specify which he probably doesn't understand the difference and therefore the odds are he used Magnetic. So, again you are better off defaulting to Magnetic.

 

Whether it's set to True or Magnetic has no bearing (pun intended) on normal geocaching. No effect of finding the cache coordinates you enter in your device. It only has meaning when using maps, compasses and bearings.

 

Is some locations on the globe the difference is too small to matter. In others the difference is large.

 

Now standby for someone to quickly jump in and disagree.

Edited by Thot

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... but I only use it with a compass and compasses are Magnetic North so I leave it set on Magnetic North.

Depends on your compass. Most good quality ones allow you to set the declination so that the compass is reading in true degrees rather then magnetic.

 

I agree that for most users True or Magnetic won't be an issue as long as the settings match on your GPSr and compass.

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... but I only use it with a compass and compasses are Magnetic North so I leave it set on Magnetic North.

Depends on your compass. Most good quality ones allow you to set the declination so that the compass is reading in true degrees rather then magnetic.

That requires you know what declination is, what the declination is in your location, and know how to set it on your compass. You can ignore all this arcane stuff entirely and just look at where the compass points north? Simple, uncomplicated -- doesn't require you understand anything about declinations, machinations and True Norths.

 

But, I appreciate you jumping in to fulfill my prophesy. :unsure:

Edited by Thot

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Depends on your compass. Most good quality ones allow you to set the declination so that the compass is reading in true degrees rather then magnetic

 

Yes, most of mine do have an adjustment, so I always read my compass true north. If they do not have an adjustment, put a mark on the declination and put the needle over this and your AZ ring will read true north.

 

You can find your declination by looking at a map, or use your GPSr. Using your GPSr, compare your bearing to a waypoint using the True and magnetic settings. Subtract the two and this is your declination. If the magnetic bearing to the waypoint is less than the True bearing, your declination is east and your mark should be east of north on the base of your compass. Again, line up the north end of the needle (often red) over this mark, and the outer ring reads true north.

 

This is helpful to know if you are using maps, outdoor navigating, or doing navigational multi-caches.

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You can find your declination by looking at a map, or use your GPSr. Using your GPSr, compare your bearing to a waypoint using the True and magnetic settings. Subtract the two and this is your declination. If the magnetic bearing to the waypoint is less than the True bearing, your declination is east and your mark should be east of north on the base of your compass.

You can get a good estimate of your local declinationfrom NOAA's site.

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