Inaccurate coordinates of caches

May 17, 2003

We have several new cachers that are placing caches in our area. I'm not sure what they are doing wrong, other than thier GPS may be set to DDMMSS or something else. I feel in the message on how to post a new cache if the cacher was told to look at the topo map of thier cache page to see if the location looked right on the topo it might help getting the coordinates right the first time.

May 17, 2003

Maybe you will do them a big favor by letting them know they are doing something wrong and help them get it right. Have you ever sent them a message directly and ask them if they would like some help?

6.5k · May 17, 2003

quote:
Originally posted by rayt333:
Maybe you will do them a big favor by letting them know they are doing something wrong and help them get it right. Have you ever sent them a message directly and ask them if they would like some help?

I agree. Politely ask them to double check the cache info. I'm actually quite shocked at the number of cachers that notice something odd about a cache, but are too afraid(??) to question it.

May 17, 2003

We placed a virtual in the Smoky Mts and our inital coordinates were off by a good bit - probably due to a combination of heavy tree cover and bad weather at the time of marking the virtual.

Fortunately the goal of the virtual was along a trail and destination was pretty clear so it didnt cause too much confusion for the first finders- they emailed me and told of the innacuracy of the coordinates. I was glad they did that! I was able to immediately change coords to the correct ones and save other cachers from stumbling about the mountainside.

I appreciated the info, 'cause I don't want to put other cachers out of their way.... but it happens sometimes, we just chalk it up to experience. We've gone on a wild goose chase or two ourselves!

May 21, 2003

I have not but from the find notes that several others have put up. The cachers must know of the problem and have not replied at least not on the cache page nor have they correct the lat. 7 long.

24.7k · May 22, 2003

I once pointed out a cache was 250' off give or take and got my butt reemed for it.

What's really cool is that all the finders after that gave the owner a good reeming in return.

Some owners are just jerks and don't realise that they are actually capable of doing a coordinate typo, or getting a bad reading.

Engineers are the worst. They can be arrogant rat bastards. Ok maybe Lawyers are worse but I'd still debate it. (Clarification, the cache owner who chewed my butt was an engineering type).

=====================

Wherever you go there you are.

[This message was edited by Renegade Knight on May 22, 2003 at 11:49 AM.]

5.3k · May 22, 2003

quote:
Originally posted by Renegade Knight:
Engineers are the worst. They can be arrogant rat bastards. Ok maybe Lawyers are worse but I'd still debate it.

HEY! I'm an engineer and I'm offended by that. Maybe I'll sue you...

"Just because I don't care doesn't mean I don't understand."

38.2k · May 22, 2003

How far off is off? If it's 40-60 feet, that's well within the margin of error and quite normal.

If it's 200 feet, then they are obviously doing something wrong.

"It has been my experience that folks who have no vices have very few virtues" -Abraham Lincoln

May 22, 2003

quote:
Originally posted by Renegade Knight:

Engineers are the worst. They can be arrogant rat bastards. Ok maybe Lawyers are worse but I'd still debate it.

=====================

Wherever you go there you are.

Hey now it is not nice to call rat bastards names, least of all compare them to lawyers or engineers, they are much better then that.

:&gt

May 26, 2003

The one of the sites was about 350-500' due south of the cache. I suppose that may have been a typo. Another was using dd.mm.ss instead on dd.mm.mm, these caches have been placed as part of a high school class. I understand that another cacher has informed the teacher of the messup. It seem he dosen't care.

May 27, 2003

We are in the process of placing our first cache. Any hints/tips on how to get the best coords would be greatly appreciated. We recently found a cache that was 95 feet off - very frustrating and I don't want that to happen to anyone searching for my cache.

38.2k · May 27, 2003

quote:
We are in the process of placing our first cache. Any hints/tips on how to get the best coords would be greatly appreciated. We recently found a cache that was 95 feet off - very frustrating and I don't want that to happen to anyone searching for my cache.

I find that as long as you have a good sat lock and let the GPS settle at the spot for a minute or so, your coordinates should be fine. I've placed close to 50 caches and I've only had complaints about the coordinates of one. And that one was one where I spent a half hour averaging my coordinates.

Another thing I do is if I can't get a strong sat lock right on the cache (perhaps it's under a boulder big enough to block signals, or close to a cliff), I'll move a short distance away and take my reading there. My reasoning is that good reading 15-20 feet away from the cache is better than a bad reading right on it. Itseems to have worked well for me.

If the first few finders complain, go back and

make an adjustment...but in most cases you won't have to.

"Au pays des aveugles, les borgnes sont rois"

May 27, 2003

It surprises me how many people DO NOT read the FAQ about how to place a geocache. It says to take several readings and pick the best one. I always seem to get a different reading from my first one at the site when I am getting coordinates for a cache. Walk off about 30-40 feet and then come back and take another waypoint.

Deer laugh when they hear my name!

http://www.geocities.com/ihunts

May 27, 2003

It never hurts to check that the datum is set to WGS 84 in the GPS. I had been using the topo maps with the GPS and had changed the datum to NAD 27 - same as the topo maps I have. Forgot to reset GPS to WGS 84. I met the first cacher to find my stache. He was off by several hundred yards for quite sometime until he went back to the spoiler.

We're all here because we're not all there.

May 28, 2003

Thanks BrianSnat and Wanderrfor your help with getting our coords right the first time. Huntnlady please don't assume I didn't read the FAQs just because I asked for a seasoned geocacher opinion.

May 30, 2003

I started geocaching a couple of months ago and finally decided to start placing my own caches. I’m using a simple Garmin Etrex Summit, which does not have an averaging function. I placed a cache last week and in order to obtain a quality set of coordinates I used the following steps: I marked the location, walked about 20 feet away, returned to the cache and remarked the cache. I repeated this process (moving away in several different directions) until the cache was marked 22 times. The marking process took me about 45 min to an a hour. I then threw out the highest and lowest values and averaged the rest.

The guy who was first to find my cache (with apparently loads of experience as seen from his profile) posts a comment with coordinates in his log (that his averaging capable unit derived) which as he states “should help others should they have problems” with mine. Using the coordinates the first finder posted and the chart in Team Markwell’s Updated Faqs, my coordinates could be off by 45 feet in both Lat and Lon! Of course, I bow to the finder’s knowledge, experience, and higher priced equipment. But, at the same time I’m confused (as well as embarrassed) as to how I might be able to obtain a higher quality coordinate for my caches. Of the 20 plus reading I took, only one was with in 20 feet of the values posted by this more experienced person.

Should I put the unit down on the cache and let it set for a couple of min. prior to marking each time during my averaging process? Any comments are very welcome.

When in trouble, when in doubt, run in circles, scream and shout!

May 30, 2003

I take an initial reading and make a waypoint at the potential cache location. I let it "average" for a couple minutes. Then, I take a little walk, maybe a couple hundred feet away, come back and make a second waypoint.

Then, on another day (the next day or several days later, doesn't matter) I go take another reading, again letting it average for a few minutes. If the coordinates are off by much (more than 20 feet or so) I come back a third day.

Then, I plot out the points graphically on paper (using the GPS distances from waypoint to waypoint and a protractor) and plot a point in the middle of the spread. You could also do this with Mapsend or whatever software your GPS can use.

Also, I check to make sure that the GPS is telling me I have a pretty good fix (20ft EPE or less) when I record the waypoints. If reception was particularly poor, I would come back another time. I use a Magellan Meriplat.

--

"I saw two shooting stars last night,

I wished on them--but they were only satellites!

Is it wrong to wish on space hardware?

I wish, I wish, I wish you'd care."

--Billy Bragg, "A New England"

[This message was edited by Team Shredded Bark on May 30, 2003 at 01:10 PM.]

May 30, 2003

I re-visited my cache since posting this morning. I was getting good reception today, with the accuracy averaging around 13 feet. I collected data for almost an hour, walking back and forth to the cache waiting for about 2 min. at the cache before recording each data set. Again, I threw out the high and the low values and averaged the remaining data. Today’ data was only 0.002 different on Lat, and 0.003 different on Lon from my original measurements! I now know that my original data was accurate enough for the cache, and there was no reason for me question my technique. After all, the first to find found it, didn’t he?

Why would he want to infer in his log that my coordinates are erroneous? Is this common?

When in trouble, when in doubt, run in circles, scream and shout!

May 30, 2003

quote:
Trodgdor said:

Why would he want to infer in his log that my coordinates are erroneous? Is this common

I've seen several caches, where a finder indicated the coordinates were off and posted their own. With some of them, the readings I got were similar to the original posters, with others, the cache hider appeared to in fact be slightly off.

Judging by the photos of the area, I wouldn't be surprised if your eTrex performed more accurately than many other types of receivers, but it's hard to tell. The terrain appears to be on the somewhat mild side of the type conditions where I would expect multipath to start affecting reception. Kind of hard to tell by photos.

I don't know if you have expertGPS or not, or access to a program that displays aerial photo maps. Looking at the coordinates for your cache, it appears you should be easily able to tell which coordinates are correct. Your waypoint is north of what appears to be a small clearing, or bare spot, judging by the topo map maybe an old railroad bed, although that isn't really what it looks like on the photo. It appears the area is fairly bare, possibly rocky, brush or grass. The Coordinates of the cache finder are approximately 71 feet away in a southerly direction on the south side of the clearing, in a clump of what appears to be small trees.

If you don't have access to photo map software, e-mail me a valid e-mail address and I'll send you a jpeg of the expertgps photomap. The e-mail address on my profile is valid.

May 30, 2003

All I usually do when placing a cache is just sit the GPS on top of or as close to the cache as possible and set it to average the position for 2-3 minutes or at least 200 samples. I have a Garmin III+. So far they have all been found and no one has made any remark about the coordinates being off.

"The best way to accelerate a Macintosh is at 9.8m/sec/sec."

-Marcus Dolengo

May 30, 2003

quote:
Originally posted by smithdw:
All I usually do when placing a cache is just sit the GPS on top of or as close to the cache as possible and set it to average the position for 2-3 minutes or at least 200 samples.

Sorry, my Etrax summit doesn't have an averaging function. As stated, I have to do my own number crunching (the old school way), and it seems to work pretty well. I've now spent almost two hours just collecting data to average by hand.

My point now is; if my coordinates were good enough for him to find my cache, why would he comment that others would need help and should use his coordinates? Is he just bragging in a "tecno weenie" sort of way about his equipment? My returning to the cache and gathering a new data set today proved that my original data was within acceptable limits of the equipment.

Seems like I'm learning more about geocachers than geocaching these days.

When in trouble, when in doubt, run in circles, scream and shout!

May 31, 2003

If he found it, the coordinates must be pretty close. After all the work you did verifying the coordinates, I'd say your coordinates to the cache are 'good enough'. There's always the possibility that his GPSr was 'off' at the time he was there due to satellite positioning, cloud cover, interference or maybe even the phase of the moon. I wouldn't worry too much about it. The way I figure it, if someone can find it, the coords must be close. If everyone (or most) finders report that the coords are off, then I'd recheck what I posted in the cache page.

Yes, you learn a lot about geocachers by reading the forums and their cache logs.

"The best way to accelerate a Macintosh is at 9.8m/sec/sec."

-Marcus Dolengo

2k · May 31, 2003

By the way. Renegade Knight has a perfect right to insult engineers. You see he is one, and yes he is also an arrogant bastard at times so he knows what he is talking about.

Lost? Keep going. You're making good time anyway!!

May 31, 2003

Perhaps the satellite prediction utilities should see more use when establishing cache coordinates.

Since the positioning accuracy(PDOP:3Dimensional; HDOP:Horizontal) is directly a function of satellite availability and geometry, one could at least be assured that system conditions are favorable at the time and place of interest.

It's the one thing an individual has control of--picking the best time. And the programs are free.

don

May 31, 2003

quote:
Originally posted by Cachetrotters:
Perhaps the satellite prediction utilities should see more use when establishing cache coordinates.

Since the positioning accuracy(PDOP:3Dimensional; HDOP:Horizontal) is directly a function of satellite availability and geometry, one could at least be assured that system conditions are favorable at the time and place of interest.

It's the one thing an individual has control of--picking the best time. And the programs are free.

don

O.K. I’ll bite, please elaborate.

When in trouble, when in doubt, run in circles, scream and shout!

May 31, 2003

Try this post, with links: Link to Magellan Mission Planning

I hope I interpreted your question above correctly.

Without going into a great deal of detail--good thing, too, 'cause I don't know any details--the number of GPS satellites *visible* to the receiver antenna and the distribution of those satellites around the sky is very important.

Those two things change daily, and hourly within each day. The prediction programs allow you to see how things will look 1, 3, or 9 hours from now, or how it will look at a cache site next Saturday at 3pm.

Things are better than they used to be, so there are very few areas that do not have good coverage all the time. But this will give you confidence.

don

24.7k · May 31, 2003

quote:
Originally posted by Night Stalker:
By the way. Renegade Knight has a perfect right to insult engineers. You see he is one, and yes he is also an arrogant bastard at times so he knows what he is talking about.

Lost? Keep going. You're making good time anyway!!

This sounds familiar. Do I know you?

=====================

Wherever you go there you are.

June 4, 2003

I have placed about 25 caches counting the multicaches. All I do is set my GPS down while I hide the cache. This normally takes a 4-5 minutes or less. I don't even attempt averaging or this multi hit business as it is not possible to tell which hit is the "best". By the time I have hidden the cache I mark the spot and use that waypoint for the lat & long. To this point I have not had anyone not find any of my caches. When I post the cache on the site I bring up the topo map on the cache page after posting to make sure it looks right in relation to other land features. When looking for a cache I goto the lat. long. and figure the cache is in a 50' radius. I have yet to not find a cache that way unless the lat. long. are way off. Most of us are using a $150 machine how accurate do you expect?

20.7k · June 5, 2003

quote:
Originally posted by Trogdor!:...
My point now is; if my coordinates were good enough for him to find my cache, why would he comment that others would need help and should use his coordinates? Is he just bragging in a "tecno weenie" sort of way about his equipment? My returning to the cache and gathering a new data set today proved that my original data was within acceptable limits of the equipment.

Seems like I'm learning more about geocachers than geocaching these days...

We must remember that geocachers are not special. We are not all pleasant, easygoing boy scouts. We have just as many jerks, idiots and egotists as the general population.

I don't know what cacher or cache you are referring to, but I wouldn't worry about it. When I place a cache, I check to see that I have a pretty good epe and I just let the unit sit for a minute or two to settle down. Then I use those coordinates.

I've placed around thirty caches I've had comments regarding my coordinates on four of them. On two, I've returned to the location and verified that my coords were good. On one, I had posted that the difficulty was adjusted as a good epe was impossible in the area. The last, my coords were off. I had marked the coords when I was with my wife (then girlfriend). She is not a cacher and I didn't take the time check my epe and let the unit settle. My coords were off. I later changed the coords on the page at the advise of the first couple of finders.

June 5, 2003

quote:
Originally posted by Stunod:

quote:
Originally posted by Renegade Knight:
Engineers are the worst. They can be arrogant rat bastards. Ok maybe Lawyers are worse but I'd still debate it.

HEY! I'm an engineer and I'm offended by that. Maybe I'll sue you...

http://208.55.63.109/images/homer.gif

__"Just because I don't care doesn't mean I don't understand."__

more than likely you'll just invent a sueing robot or perhaps a car-keying robot

20.7k · June 6, 2003

Need a good lawyer?

June 8, 2003

quote:
Originally posted by Renegade Knight: Engineers are the worst. They can be arrogant rat bastards. Ok maybe Lawyers are worse but I'd still debate it. (Clarification, the cache owner who chewed my butt was an engineering type).]

My business parter is BOTH an engineer AND a lawyer. I won't even go into how much fun he can be to work with.

Jolly R. Blackburn

http://kenzerco.com

June 9, 2003

All very interesting info.

One comment. All that walking around a newly placed cache may leave a 'herd of elk just strolled through' look to that perfect hide. I'm a novice, yes, but sometimes I'll get to the cords and just look around for obvious trails, tracks, broken twigs, whatever looks unnatural. No, I'm no tracker just like to keep my eye balls working.

Inaccurate coordinates of caches

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