Posted Coords-Estimate or Validate?

[+infiniteMPG]

A common complaint in some forum postings has been about the accuracy of the posted coordinates of some hides. We all have experienced this and from an owner’s point of view, our GPSr is no more accurate then the seeker’s is. Compound those two things and you could get some pretty broad variations

 

The reason for this post is to see what the different methods are that owner’s use to validate the coords they’re Waymarking for their hides. For me I always stand directly at GZ and hold my MAP60CSx still and wait for the accuracy to settle to it’s most accurate reading. I mark the point and then walk about 20-30 feet away. I do a find on the waymark and see if it takes me back to GZ. Then I repeat this several times from several different directions. If my coords aren’t settling well (heavy cover, story day, etc) I’ll waymark several points at GZ and then re-approach several times from several directions and see which one hold truer. Regardless, I never mark the spot and leave, I always check.

 

If I do cache maintenance at the hide, I always check the coords again as I have found that the conditions might be better then when I hid it and I want them as close as I can. I also recently upgraded from a MAP60C to a MAP60CSx so I trust my newer numbers better. And if cachers email or log issues with the coords, it gets added to my maintenance list.

 

I am always out to improve my hides and improving my listed coords falls under that umbrella, so I figured it’d be nice to hear how other owners validate their coords

[+StarBrand]

Let the unit settle at the spot for about 10 minutes. Take a reading and call it good. Check the maps when I get home.

 

If you search back a few years though my old posts, I had some other techniques but the above has worked just as equally well as anything else I have tried.

[+Walkworthy & Wife]

I own a Garmin eTrex Venture HC that has a feature under "Mark", where you can average the coordinates of your cache. I do at least 30 readings. I then go back in a day or two when the satellites have changed positions and get another average of 30 readings. So far, knock on wood, I haven't gotten any complaints

Edited November 21, 2008 by Walkworthy

[+trainlove]

For Magellans I also find it good to, after doing all that has been mentioned here so far, turn the GPS OFF and then turn it back ON again at the cache site. Wait for re-acquisition, wait for a 3D fix, wait for WAAS to have Fast, Long and Iono corrections from at least 4 or 5 satellites, wait for a low EPE reading and then take those coordinates in addition to the others I've collected. This noly adds a minute or so to my routine.

[+infiniteMPG]

Let the unit settle at the spot for about 10 minutes. Take a reading and call it good. Check the maps when I get home.

I used to do that but then I found once that I had good accuracy and settled coords. Then I walked away, turned around and did a find and when I reached GZ my GPSr was telling me I was 20-30 feet away. ACK! So ever since then I always check a couple times. I did maintenance on five caches last evening and updated the coords on several as my GPSr was taking me 10-feet or so from GZ. 10-feet is normally acceptable, but when you get good readings that hold less then that, you stick with them.

 

I own a Garmin eTrex Venture HC that has a feature under "Mark", where you can average the coordinates of your cache. I do at least 30 readings. I then go back in a day or two when the satellites have changed positions and get another average of 30 readings. So far, knock on wood, I haven't gotten any complaints

Someone else spoke to me about "averaging" but I haven't looked into it yet. The eTrax and the MAP60CSx have a lot of same features so I am sure the MAP60CSx can do that.

 

Oh yeah, forgot to mention that often I plug the coords into Google Earth or Google Maps and look at where the satellite is telling me the coords are and that can flag a potential issue.

Edited November 21, 2008 by infiniteMPG

[+Renegade Knight]

I put the GPS down tell it to average and hide the cache. When I'm done I take that point. If I forget I just take one point by the cache and call it good.

 

When I list I use the topo links to rule out a major typo from inputing my coords. It's saved my butt a couple of times.

[+Leaky Spoon]

We take two GPSrs with us. The Venture Cx averages, while the Rino 530 takes several readings. When ours are both as close in number as we can get, we choose that spot.

[+Harry Dolphin]

MY QC department requires the best! We average the reading, walk off 50 feet, and approach again. If that doesn't seem to work, we try again, and again. Then we give up and use the one that seems to work the best. For our newest cache hide, we had three points (about 15 feet apart). #2 worked consistently the best. The three finders all said that the coords were spot on.

[+WRASTRO]

This is a topic for which there is no one right answer. I have a cache that I have measured multiple times over three years with a Garmn and with a Magellan. Both units give me essentially the same coordinates. Some cachers say the coordinates are right on while other feel compelled to post revised coordinates, right down to .001 north! When I get that close I am not even looking at my GPS.

 

We typically visit several times over a period of days and use the average of the readings we get. This seems to work pretty well for us.

[Skippermark]

Let the unit settle at the spot for about 10 minutes. Take a reading and call it good. Check the maps when I get home.

I used to do that but then I found once that I had good accuracy and settled coords. Then I walked away, turned around and did a find and when I reached GZ my GPSr was telling me I was 20-30 feet away. ACK! So ever since then I always check a couple times. I did maintenance on five caches last evening and updated the coords on several as my GPSr was taking me 10-feet or so from GZ. 10-feet is normally acceptable, but when you get good readings that hold less then that, you stick with them.

I find that if I set the GPS down while hiding the cache, then take a reading, walk away and come back, the coords can be off a bit. I think that if you go there and take a reading and the GPS doesn't have a good signal for whatever reason and mark it (or average it), even after 10 minutes, you're just getting an average of bad coords.

 

I follow the iMPG approach, walk to the cache, let the GPS settle, mark the waypoint, walk away and approach for a few different directions. It seems to work, and most of the logs say the coords are good, except for one that's in a 20' wide cutout between 2 rock walls about 50' tall. That one is iffy and can be good one day and way off another.

 

I did get a chuckle out of iMPG's note when he said, "ACK!" that his coords were 20-30 feet off. Here in CT (maybe because we're further north, have lots of of rock with metals in them or something else, but 20 feet or less is considered good coords. 30 is okay too unless you're out in the open. I'm a little less tolerant then my friends who say 45' off isn't even that bad. I wouldn't be happy if one of my caches was that far off and try for 20' or less.

 

But, it's true that in FL (and other places) that 20-30 would be bad. When we first cached in FL, we put the GPS into our pockets when we got to within 30 feet and started looking. We quickly learned to keep it out till you got to 10' and if you were more than 15' away, you were "far" from the cache most of the time. It was a nice change.

Edited November 22, 2008 by Skippermark

[+Star*Hopper]

Basically, I take a preliminary mark & mentally note the last 3 digits of both the N & W coordinate, then switch to the Satellites screen.

 

I watch the accuracy number and when it holds on the lowest for a few seconds, compare the same 3-digits to what's displayed. They're usually, but not always, very close - one might drift 2-4 thousandths. Mentally note that too - what they are reading.

 

Then do what I call the 'walkoff'....same as you've described: 40-50 feet, & in different directions when available....watching the accuracy reading as I then walk back to the GZ while comparing the mentally noted figures. Repeat as many times (and from different directions when possible) as it takes until I'm reasonably sure I've got my best reading.

 

Switch back to the Mark screen - tweak the numbers recorded if necessary....then do a couple more walkoffs & back to test....and I leave.

 

While on the Satellites page, I also observe & note the "spread" & the signals I'm getting from each. If the ones I'm reading & that are giving the stronger signals have a good spread across the sky - not in a cluster, I'm done.

 

If they're bunched, I don't entirely trust the reading, and USUALLY make it a point to return another day to check the GoTo & see how close it puts me, & tweak as necessary before publishing. I say 'usually', because I've placed a few caches where uber-accuracy really wasn't an absolute necessity, & knew that getting folks near GZ was all that was needed. Example - a real caboose/ticket office at a park's Kiddy Train Ride ... just got 'em to the correct end of the caboose.

 

~*

[+BlueDeuce]

I follow the iMPG approach, walk to the cache, let the GPS settle, mark the waypoint, walk away and approach for a few different directions. It seems to work, and most of the logs say the coords are good, except for one that's in a 20' wide cutout between 2 rock walls about 50' tall. That one is iffy and can be good one day and way off another.

 

ayep.