Unsuccessful First Attempt... Too high of expectations?

[Soulmate Wanderers]

Discovered letterboxing last week and then Geocashing a couple of days later. Ran out and bought a "Sportrak Map" to have this past weekend. Did a crash selflearning course on using it and went on our first geocache hunt. Maybe we expected to much? My impression was that a GPS rated accurate to 3 meters and geocache coorinates would basically put us within 3 to 10 feet of the spot of the cashe. We were in a somewhat wooded area but there are no leaves on the trees and should have enough clear sky in my opinion for a good reading etc. I read all messages for clues etc including spoilers. I surely wanted to just easily find our first one without hunting for a long time. I got some conflicting reading from my waypoint. Sometimes the reciever would say I'd be 100' west of the spot and then when I went there it would say I was 200' east and I'd only maybe went 50 feet or so. I didn't expect to have to look in a 200 foot area for a hidden box. After looking around a larger than I felt necessary area, we not only didn't find the cashe, didn't find any landmarks hinted about.

Our main questions are: What SHOULD our expectations be? Do you get pretty close to a cashe or do you really have to look around a pretty wide area? We like the idea of hiking and walking about but not staying for a long period of time in an area on an "easter egg hunt". How really accurate are GPS units and how really accurate are the cooridantes given for the cashe?

We were so excited to pursue this and after a big dissapointment would like to get some enthusiam back. please help!

[hostetter]

My etrex was doing the same thing this weekend, here in GA. Distance away was bouncing all over the place. Made it very challenging to find caches. The first few caches I have found in previous weeks, my etrex put me within 40 feet which was fine. This weekend it put me merely in the neighborhood and I had to do a lot of searching to find the caches. I think you should normally expect to get within 20-40 feet, although sometimes you might get <10 feet away.

[+gebu]

GPSr don´t really like dense forests. The skipping you experienced was because the GPS only sporadically recieved signals and had the recalculate your (possibly inaccurate) position each time.

In such a case it´s best to find a sufficiently large clearing, wait a 30 secs or so until you get a reasonable accuracy (<40 feet), remember the distance and bearing to the cache and use your sight&go-feature [don´t know what it´s called on your Sportrack) and walk the projected distance in the direction of the cache. Repeat this if necessary from different locations and you soon should be able to narrow the searching area down.

Alternativly pester the cache-owner for additional info where the cache is hidden - usually you get a response very quick.

[+Mopar]

Welcome Soulmates!

One little quirk I've noticed with the sportrak line is it's auto averaging. Without getting technical, basically with that model gps when you start walking slow, like when you get near the cache, it starts averaging its readings to try and get a more accurate fix. In general, this might be a good idea, but for geocaching purposes, it gives a slingshot effect. Since its always averaging you current position with the position fix it averaged a second ago, it can lag behind where you really are. I've found it best with the sportrak to just stop when I get to 100ft or so, and let it catch up. The arrow on the Sportrak looks like a compass, but it isn't a true compass. It only knows direction as long as you are moving, so while I am standing there, I use the heading in the BEARING field of the GPS with my handheld compass (about $8 for a halfway decent one for geocaching) to determine what direction to continue walking. At about 50ft away, I will stop and do the same thing. At this point, when the GPS settles down, I'm usually 25-35ft away. I try to mentally sight a line with the compass in the direction it shows, then circle 1/4 way around and do the same thing. Where my 2 mental lines intersect, I walk over a put down my pack and the GPS. I then just start searching likely spots, starting at my pack and working my way out. As you find more and more, you will start to notice clues, and likely hiding places. Some call that "the force", and many good cachers can just scan the area and walk right up to the cache using "the force".

Also, make sure you start out with some simple caches at first. You will be amazed at how devious some of the higher difficult caches are camouflaged!

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

[+canadazuuk]

try another cache... trust me on this

 

As someone will likely say sooner or later, there are two parts to geocaching...

 

geo

 

and

 

caching

 

sometimes the geo part doesn't work out quite right

 

zuuk

[+Searching_ut]

You sportrak is a very accurate unit, when it has unobstructed views of the sky. In tougher conditions however, it does just as you describe. Most of the time when mine starts giving me different readings for the same spot that are hundreds of feet apart I'm in a tree filled canyon. Drives the unit nuts sometimes. But there are ways to work around it.

 

Part of the fun of the game is figuring out how to best use your receiver. In some areas, you have to seek out spots where you get good reception, then navigate from there using the data the unit gave you, a good old compass, and old fashioned techniques to guess distance. Sometimes just holding the unit a little differently will do the trick, or maybe longer periods of averaging.

 

The more you play the game, the better you'll get at maximizing the capability of the receiver, and basic navigation in general

 

Try a few more, it comes with practice.

[+Renegade Knight]

Mopar has given you a good take on a quirk of the Sport Trac/Magellans.

 

All GPS's are subject to signal bounce and other things that mess up a good signal.

 

You were in a forest with no leaves but, you still have branches that bounce signals and have water in them that block or partially block signals.

 

Over time you will get a feel for what causes problems and how to adjust to them.

 

All in all, this is part of why I have to look at people funny when they say "so you take a gps and walk right up to the cache...that's easy how hard can it be?"

 

Wherever you go there you are.

[+brad.32]

quote:

---

Originally posted by Renegade Knight:

...I have to look at people funny when they say "so you take a gps and walk right up to the cache...that's easy how hard can it be?"

---

 

They haven't geocached in a redwood forest.

 

"Last time I had a position we were about 800m away."

"What are we now?"

"300, so we're on the right trail"

[Aksor+Raskol]

Remember that the person who placed the cache may have done in under heavy leaf cover in summer, or picked a day when reception wasn't best, and he may have placed it with the GPSr giving him no more than a certain degree of accuracy. If the GPSr gave him a set of coordinates, but the degree of accuracy is, say 30', then he was already off by a 60' diameter circle. Now you go looking for it with the same degree of accuracy and you could be off by 120'. Take that into consideration and don't give up. Look for the clues listed. Look for likely hiding spots, trampled grass, broken twigs. Your senses will sharpen with each cache you find. You will find some that the GPS will literally point you to, and you'll wonder why you had so much trouble with the last attempt. Keep with it and don't be discouraged. I have a cache on my list that I've been to twice with no success, and now I see that others who have found it have noted in the logs that the coords were off by 50' and have posted new coordinates on the log. I'll bet I'm successful next time I hunt it

[+Kordite]

I, too, had a similar first experience.

 

My problem was that I was in a downtown area. The many high buildings made it difficult to get a good satelite lock and so the accuracy was very poor. I was running al over the place for a while. Being in the woods can have a similar effect, and the trees block a clear view of the sky.

 

I was looking at the wrong display window. My GPSr (a Megellan Platimnum) has a window that shows Latitude and Longitude. It will also say "Searching for 1st sat.", "Searching for 2nd sat". I've learned that until it finds 4 satellites and starts saying "Averaging", I shouldn't even bother looking at any direction or mapping information.

 

Then, once it has 4 satellites, it will have a line that says EPS. This is an estimated accuracy. It might say "EPS 36", which means that the Lat/Lon reading is within 36 feet.

 

Also, my GPSr is WAAS enabled. I don't remember offhand what the acronym stands for but what it means is that the GPSr listes to several additional satellites to make adjustments to the reading even more accurate. It can get to within 9 feet.

 

The Sportrack Map should have the same features as mine. Before you go following the compass that points you in the direction of the waypoint, look at the screen that shows Latitude, Longitude and altitude. That will also show you if its found all the satellites it needs and the estimated accuracy of the reading once its found them.

 

So, follow the waypoint and cache description until you get pretty close. Then stop. Make sure you've got all the satellites. What it the EPS? Do you have WAAS?

 

Once you are confident of where you are you can get a reading on the cache and make a go for it. Learn how to judge distances by paces so you are not blindly following the GPS which, in the woods may have problems keeping accurate as satelite signals drop in and out because of the tree clutter. For example; I know that my standard stride is about 6 paces to 5 meters.

 

Once you've gone that distance, check your GPSr again, including it's accuracy. This start and stop approach an keep you from following phantoms as signal drops in and out.

 

Good luck, good hunting and don't hit your head.

 

Kordite

[+DustyJacket]

Dont forget:

You have the accuracy of your unit, perhaps degraded by trees.

You have the accuracy of the hider's unit, perhaps degraded by trees.

 

Some days you can be right on, and othes way off.

Develop an eye for hiding places, and enjoy the hunt.

 

DustyJacket

...If life was fair, a banana split would cure cancer.

[+The Good Shepherds]

Make sure the "datum" setting on your GPS unit is set to "WGS84"- if it isn't set to this, your readings will be offset by something in the order of 100m - that's a big enough difference to ruin your chances of finding a cache, but small enough for you not to notice something is badly wrong in terms of your general location. Many newbie cachers fall foul of this gotcha on their first trip!

[Soulmate Wanderers]

These were all GREAT tips! Thanks to everyone! We're doing great now. Mopar's tip has helped a lot! We've had a nice Silva compass that we now always take with us. When we get around 20 to 50 feet from the cashe, I dial up the GPS bearing reading on the compass, turn till the needle is lined to north and the compass points right to the cashe. Is working like a charm! Thanks again!

Glad to join in with such a great bunch of people!

[Wandering Willy]

Although "Selective Availability" (the DoD messing up the signals to make them less accurate) is generally off now there is still some testing (jamming, etc) done in some areas which will temporarily throw off the accuracy of the GPS. Not often and not in many places. But if you are standing in one place and your GPS is "wandering" that could be a problem, too. The FAA posts notices to pilots where and when GPS will be inaccurate for navigation purposes. I don't know if that information is available anywhere else.

 

WW

[+roricka]

I found the first cache I sought, but then failed on the next two. The first one was under a pile of brush. My question: are these things often (or ever?) buried? I would think not, given the accuracy issues, as discussed in this thread. I mean, you'd have to dig an awful lot of holes. After I have a few dozen under my belt I'll know the answer, but can somebody give me a head start?

[Aladin Sane]

Covered by leaves, brush, etc, yes. Buried in the earth, no.

[ExactlyAmy]

I don't know why, but mine does that too. I have an eTrex Venture, and it has played with my mind several times now. I will be nearing a cache.. getting within 20 feet or so. Then it tells me "Hey you need to go 70 feet that way -->" I think 70 feet seems odd, but okay I'll go. I get about 20 feet that way and it says "hey sucker gotcha again. Now you need to go 10-15 feet back exactly the way you came from. I was only joking about the 70 feet hahahahhaha". It's as if I can hear the thing laughing and maybe that's just it's way of enjoying geocaching since it never brings anything to trade.

(Is it anything to be alarmed about if I'm talking as if my GPS is not an inanimate object?)

[Keystone Two]

Missing from this excellent discussion with terrific hints and information is the possibility that the cache may not be there. It might have been plundered.

 

I'm glad the cacher stuck with it...no fun to have a skunk on the first outing!

[dsandbro]

The 'accuracy' will vary throughout the day as the satellites move. Download any of the almanac programs mentioned on this site and check the satellite graphs before you leave. Over the space of a few minutes to hours the unit's accuracy (expressed as PDOP, EPE, etc.) will jump all over the place as satellites move into and out of view, and change geometry relative to each other.

 

It's not merely the number of satellites, but the distance and angles between them.

 

Remember how you triangulate with a map and compass? Shoot a bearing to a distant object and draw that line on the map. Do the same for another object. Your location is the intersection of the two lines. If the lines intersect at close to a 90 degree angle the accuracy of your fix is much higher than if they intersect close to a 180 or 0 degree angle. GPS works the same way. If all the satellites are 'clustered' in the same part of the sky the accuracy will be off (or if clustered in two parts of the sky and you are right in the middle between them). If the satellites are well dispersed accuracy will be better. If they are low in the sky accuracy is less than if they are higher (for technical reasons directly overhead is also bad). In these cases just wait a half-hour or so and see if things improve.

 

Keep as little as possible between the GPS antennae and open sky. This includes your own body. Look on the satellite screen and note where the satellites are relative to you. Move around slightly so there as much open sky as possible in that direction (bare branches affect signal too, less than full foliage but still an effect). If you hold the unit in your hand face that direction. If the signal is still bad consider taking off your backpack (Don't laugh. Does your pack contain a metal frame, a metal container, lunch wrapped in aluminum foil, cell phone, radio, PDA, Walkman, etc?). Individually the effect of these things are minor to insignificant. Combined it can be appreciable.

 

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Friends don't let Friends geocache drunk.