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Magnetic or True North Which does geochaching.com use?

#1 User is offline   SkellyCA 

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Posted 11 December 2008 - 07:21 PM

Do the coordinance posted on geocaching.com use magnetic or true north as a reference?

I'm having trouble finding a cache...Happy Birthday JoeSpaz #38(GC11Q7X)

and I'm wondering if this why? I have my software and GPSr set to magnetic north.

Do you know how much of a difference that would make?

#2 User is offline   Too Tall John 

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Posted 11 December 2008 - 07:32 PM

Which North (True or Magnetic) should not effect the coordinates given.

If you were working on a waypoint-projection puzzle cache, it would matter, although to my knowledge, GC.com has no standard, the cache owner usually specifies which you should use.

#3 User is offline   SkellyCA 

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Posted 11 December 2008 - 08:28 PM

View PostToo Tall John, on Dec 11 2008, 07:32 PM, said:

Which North (True or Magnetic) should not effect the coordinates given.

If you were working on a waypoint-projection puzzle cache, it would matter, although to my knowledge, GC.com has no standard, the cache owner usually specifies which you should use.



Thank you

#4 User is offline   Wacka 

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Posted 11 December 2008 - 09:24 PM

That cache, if hidden correctly is hard to find. Unless it is stated in the cache listing, always use true north.

#5 User is offline   Chrysalides 

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Posted 12 December 2008 - 12:49 AM

View PostSkellyCA, on Dec 11 2008, 07:21 PM, said:

I'm having trouble finding a cache...Happy Birthday JoeSpaz #38(GC11Q7X)

Hi, Skelly. I found this cache today and noticed your DNF when I was logging.

The cache is there. Use the hints. But the coordinates are not very precise - it led me to the middle of a bush, and that is definitely not what the hint was referring to. Someone posted better coordinates but I didn't use them because I forgot to bring them along :D But it is not very far off.

As for true north vs. magnetic north, it's only to do with bearing, not coordinates. If you go from N 33 W 122 to N 34 W 122 your bearing is true north.

Edit : so far the only cache I've encountered around this area that uses bearings is GeoWomyn's puzzle cache Nefertiti's Pyramid in Dry Creek. The instructions say to bring a magnetic compass for the final stage. I'm sure there are more.

This post has been edited by Chrysalides: 12 December 2008 - 12:54 AM


#6 User is offline   Markwell 

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Posted 12 December 2008 - 05:18 AM

http://markwell.us/geofaq.htm#truemag

#7 User is offline   Skippermark 

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Posted 12 December 2008 - 05:57 AM

SkellyCA, it looks like the cache may be in a "bouncy" area where it's hard to get a precise GPS signal. A previous finder posted some alternate coords where their GPS had them. You might try those to see if they work for you.

#8 User is offline   trainlove 

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Posted 12 December 2008 - 09:02 AM

To be honest Geocaching..com uses neither. Angles are only shown on a search page and there it has to be True since they refer to a great circle path from your coordinate to the caches coordinates.

What you use on youtr GPS is up to you since it's you using just your GPS, or a GPS and a compass, or your GPS and the position of the Sun and Moon (like I do)...
When it comes to puzzle caches, it all depends of the hider, and if he doesn't say which to use, then that's part of the puzzle, LOL.

#9 User is offline   Mr.Yuck 

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Posted 12 December 2008 - 09:10 AM

View PostMarkwell, on Dec 12 2008, 05:18 AM, said:



Very nice. I knew all that stuff actually. Silly Army map training. :D But one thing I notice on that page, Markwell links to Jeeep coordinate translation, and it works! The link had disappeared for quite some time, to the point where Geocaching.com even went out and made their own at www.geocaching.com/wpt but the Jeeep translation is finally back, new and improved.

Markwell also does a great job of explaining how true and magnetic North differs according to where you are on the globe. If you're ever in Columbus, Georgia, you'll never have to worry about the true and magnetic thing. It's the same. :D A few other spots on earth too, I'd imagine.

#10 User is offline   GIDEON-X 

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Posted 12 December 2008 - 10:48 AM

True or Mag.....depedns what your doing I guess. I have several caches here in the Yuma, AZ area that call for projecting a waypoint, on these cache pages I note to use "Mag North"...........in this area there is 17 Degrees (off-set) which in fact will make a big difference.
My Cache Page

#11 User is offline   SkellyCA 

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Posted 12 December 2008 - 12:33 PM

View PostChrysalides, on Dec 12 2008, 12:49 AM, said:

View PostSkellyCA, on Dec 11 2008, 07:21 PM, said:

I'm having trouble finding a cache...Happy Birthday JoeSpaz #38(GC11Q7X)

Hi, Skelly. I found this cache today and noticed your DNF when I was logging.

The cache is there. Use the hints. But the coordinates are not very precise - it led me to the middle of a bush, and that is definitely not what the hint was referring to. Someone posted better coordinates but I didn't use them because I forgot to bring them along :D But it is not very far off.

As for true north vs. magnetic north, it's only to do with bearing, not coordinates. If you go from N 33 W 122 to N 34 W 122 your bearing is true north.

Edit : so far the only cache I've encountered around this area that uses bearings is GeoWomyn's puzzle cache Nefertiti's Pyramid in Dry Creek. The instructions say to bring a magnetic compass for the final stage. I'm sure there are more.


The map on the page shows it on side of the pond, the coordinace too me to the other side. Hmmmm

#12 User is offline   Chrysalides 

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Posted 12 December 2008 - 04:29 PM

View PostSkellyCA, on Dec 12 2008, 12:33 PM, said:

The map on the page shows it on side of the pond, the coordinace too me to the other side. Hmmmm

The other side of the pond?? :) When did you last update your PQ? I noticed that in July 27 the CO incorrectly updated the coordinates to somewhere in the middle of the lake, but he quickly changed it back on the same day.

According to Google Maps, the correct coordinates should be : N 37 34.435 W 121 59.144

I e-mailed the CO about this and a separate cache, he mentioned that he will be checking the coordinates.

#13 User is offline   SkellyCA 

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Posted 12 December 2008 - 06:00 PM

View PostChrysalides, on Dec 12 2008, 04:29 PM, said:

View PostSkellyCA, on Dec 12 2008, 12:33 PM, said:

The map on the page shows it on side of the pond, the coordinace too me to the other side. Hmmmm

The other side of the pond?? :) When did you last update your PQ? I noticed that in July 27 the CO incorrectly updated the coordinates to somewhere in the middle of the lake, but he quickly changed it back on the same day.

According to Google Maps, the correct coordinates should be : N 37 34.435 W 121 59.144

I e-mailed the CO about this and a separate cache, he mentioned that he will be checking the coordinates.


I used these posted august 6th in the logs...

N 37* 34.435 W 121* 59.146 I cnoverted them to decimal on the Other Conversion page and got...

Decimal W 37.57392 - N 121.98577

so maybe the conversion is wrong?

#14 User is offline   Chrysalides 

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Posted 13 December 2008 - 10:54 AM

View PostSkellyCA, on Dec 12 2008, 06:00 PM, said:

I used these posted august 6th in the logs...

N 37* 34.435 W 121* 59.146 I cnoverted them to decimal on the Other Conversion page and got...

Decimal W 37.57392 - N 121.98577

so maybe the conversion is wrong?

No, they check out for me (using a calculator). Did you enter them incorrectly into your GPSr? By the way, why do you use decimal degrees? Just wondering, because it adds an extra step to the process.

#15 User is offline   SkellyCA 

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Posted 13 December 2008 - 11:10 AM

View PostChrysalides, on Dec 13 2008, 10:54 AM, said:

View PostSkellyCA, on Dec 12 2008, 06:00 PM, said:

I used these posted august 6th in the logs...

N 37* 34.435 W 121* 59.146 I cnoverted them to decimal on the Other Conversion page and got...

Decimal W 37.57392 - N 121.98577

so maybe the conversion is wrong?

No, they check out for me (using a calculator). Did you enter them incorrectly into your GPSr? By the way, why do you use decimal degrees? Just wondering, because it adds an extra step to the process.


I use decimal because I can't figure out how to get my Magellan Triton 400 to do degrees, minutes and seconds

and yes, I've checked the coordinace in my GPSr a couple dozen times anfd they are correct.

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