How accurate should coordinates be?

[Fungus Foragers]

I'm new to geocaching, but the most recent cache I found was quite a way from its published coordinates. That said, the location was pretty obvious. Two questions - how accurate can I reasonably expect the coordinates to be and what do I do if they're wrong (aside from checking my own coordinates)?

[+kunarion]

what do I do if they're wrong (aside from checking my own coordinates)?

Send a Message to the Cache Owner, mention the new coordinates you got. In your log, you can note that the coords seem to be off by (distance), and if there are other logs saying that, it's probably an issue.

 

You can reasonably expect to get within 40 feet of GZ, if you have a decent GPSr in hiking mode (NOT street routing!), with good reception. You can plug those coords (both from the cache page, and your new improved coords) into a couple of online maps, in "satellite view", and see how the cache sits in relation to some landmark. That may help you decide what the problem is.

Edited December 27, 2010 by kunarion

[+dfx]

In your log, you can note that the coords seem to be off by (distance), and if there are other logs saying that, it's probably an issue.

 

or you just post your own coords in the log if it's a traditional. this can both help the CO and future seekers.

 

coordinates generally should be as accurate as possible. my personal expectation is 5-6 meters as this is what GPS is rated at. with modern receivers and averaging it's possible to get much higher accuracy though, within 2 meters or even better (at which point the rounding error becomes significant), but of course your own receiver must be just as good and reception must be good also to actually make use of that.

[+2BAMBAM4]

I'm new to geocaching, but the most recent cache I found was quite a way from its published coordinates. That said, the location was pretty obvious. Two questions - how accurate can I reasonably expect the coordinates to be and what do I do if they're wrong (aside from checking my own coordinates)?

 

I am newer as well. But, I have found that coordinates often depend upon the GPS' (age, style,sky view,fresh batteries). Also check the "accuracy" of the gps when in the area as the gps will give a notation that the current accuracy is "within 30 feet" etc. (equates to a 60 foot diameter circle) I always try and let my gps sit for a couple minutes in general area to try and get the most accurate reading for my cache placements. With that said recently I placed a cache and another cacher had readings that were 100 feet different. So it is not uncommon when finding a cache that coords are different than posted that the finder adds the coords into the comments of the find post. If only a couple numbers off no need to post new coords, just part of the game.

[+niraD]

Posted coordinates should be as accurate as possible. However, under ideal conditions, a consumer GPSr will be accurate to about 3m (10'). That applies both to the GPSr of the cache seeker, and to the GPSr of the cache owner, so you may find the container 15-20' from ground zero under ideal conditions. Under less than ideal conditions, both GPSr readings can be much less accurate.

[+Ike 13]

If you're hiding a cache they should be dead on. Searching will vary. Not all cache owners take time to get multiple readings and even if they do their GPS or your GPS could be a little off. The older the cache the higher the chance the coords are off. I accept anything within 30 feet but most new hides are becoming more and more accurate. If it's more than 30 ft I let the CO know and I may add my readings to my log for future hunters.

[+humboldt flier]

Co-ords taken multiple times directly on top of the cache averaging the waypoints is a good idea. NOTHING replaces " boots on the ground with an accurate GPS'r ".

 

Utilization of various phone systems and or mapping systems is not a good idea. > In fact they are bad ideas. <

 

HOWEVER, a worse idea is offsetting the co-ords and publishing the cache as a traditional.

( Oh these co-ords are O.K. but that spot over there has more hiding places ... I think I'll hide it over there. Tee, Hee, Hee )

 

If one wants to play the " offset game ":

 

Offset notification should occur early and prominently in the cache description.

 

Publication should be as a puzzle cache as opposed to traditional.

[+t4e]

I'm new to geocaching, but the most recent cache I found was quite a way from its published coordinates. That said, the location was pretty obvious. Two questions - how accurate can I reasonably expect the coordinates to be and what do I do if they're wrong (aside from checking my own coordinates)?

 

what GPS are you using?

[+Anno Lynke]

where you are standing and the conditions at the time matter also

we have this nice thing called signal bounce

I was looking for a cach downtown

with a friend between us we had 4 gps

I sat down and watched my gps say I was moving back and forth across the street

we had almost 100 ft circle we were looking in

the google map had it dead on where I found it

but the signal was bouncing off the buildings so bad i couldnt get a gps fix

 

Another time in the woods I was 60 ft away from the cach the leaves were messing with the signal

I found it using the clue. the person hiding it may have hid it in the fall when there were no leaves

[+michigansnorkelers]

Here is an informative exercise if your GPSr has tracking:

 

Find a safe place with a good view of the sky...start tracking...then leave the GPSr alone for a hour or as long as you can.

 

When you return and look at the map display, it will appear that the GPSr had been moving around. Of course, it was stationary; the coordinates had drifted.

 

This shows you the inherant error of your device.

[Fungus Foragers]

what GPS are you using?

 

Memory Map A2800 - the correlation between the GPS position and the OS mapping is excellent.

 

Here is an informative exercise if your GPSr has tracking:

<snip>

 

Thanks for that! There's usually a good match between my planned route and the recorded track, but this time there was a huge discrepancy in terms of the distance travelled. Maybe the A2800 was having a bad day, though there was good agreement with the map position, at least for the mapping scale I was using. WRT signal bounce, there was a low wall about 20 yards away but otherwise it was open countryside.

Edited December 28, 2010 by Fungus Foragers

[+MI_CO]

I consider anything within 10-15 feet as really accurate, 20-30 as acceptable, and anything over 40 feet I mention it in my log. As others have mentioned, many things will affect your GPS's accuracy - heavy cloud cover, heavy tree cover, how many satellites you are locked on, if you are using magnetic north, etc. When I am having trouble getting my GPS to settle down, I will switch from the compass feature that says I am so many feet from the cache and use the actual long/lat readings and that generally takes me to the cache.

 

If I find myself more than 30 feet from where the web page says, I place my GPS on the ground at the cache site and leave it there for a few minutes, and check the actual long/lat reading. You may be surprised at how accurate the long/lat reading is according to the cache page using this method, and how 'off' your compass/feet to cache is!

 

That said, the accuracy of the coordinates are soley dependent on the accuracy of cache owners. Some cache owners like to put the seekers in the general area of the cache and want the cache seekers to use their 'geosenses' to locate the actual container; some cache owners are always dead on.

[+dfx]

You may be surprised at how accurate the long/lat reading is according to the cache page using this method, and how 'off' your compass/feet to cache is!

 

what exactly do you mean by that?

[+AlohaBra and MaksMom]

I consider anything within 10-15 feet as really accurate, 20-30 as acceptable, and anything over 40 feet I mention it in my log. As others have mentioned, many things will affect your GPS's accuracy - heavy cloud cover, heavy tree cover, how many satellites you are locked on, if you are using magnetic north, etc. When I am having trouble getting my GPS to settle down, I will switch from the compass feature that says I am so many feet from the cache and use the actual long/lat readings and that generally takes me to the cache.

 

If I find myself more than 30 feet from where the web page says, I place my GPS on the ground at the cache site and leave it there for a few minutes, and check the actual long/lat reading. You may be surprised at how accurate the long/lat reading is according to the cache page using this method, and how 'off' your compass/feet to cache is!

 

That said, the accuracy of the coordinates are soley dependent on the accuracy of cache owners. Some cache owners like to put the seekers in the general area of the cache and want the cache seekers to use their 'geosenses' to locate the actual container; some cache owners are always dead on.

 

i Phones and smartphones are not as accurate as GPS receivers meant for geocaching, hiking or boating, etc....

I expect 10 to 15 feet accuracy from the CO in today's climate....30 feet is way off...but can be expected ....

More people are getting into caching with smartphones, so you have to use some psychology nowadays about the accuracy....

Edited December 30, 2010 by alohabra