+Morningofthesun Posted January 12, 2009 Share Posted January 12, 2009 Hey Fellow Cachers A newbie here - with (Proudly) 81 finds under her belt Okay, so I'm finally getting enough confidence to hide my own. I got everything we need to place it - and tried to do so this weekend, and we hit a BIG bump! Accuracy? I just don't understand what we did wrong or if it was out of our hands. You mark an area, and then put it as your waypoint and you should be able to get relitively close to where you marked, right? But we also noticed, our accuracy on our gps was 14ft. How in the world do you hide a cache with 14 feet accuracy and expect other people to find it? My husband and I spent OVER 2 hours trying to hide a cache. Yet, when we marked our car, it brought us back to it just fine. So what do I need to consider? Telephone lines, tree canopy's, what else? I just can't hide it in an open space. My fear is hiding this cache and nobody being able to find it. I've read and researched, and they all say to mark it quite a bit of times to make sure your coordinates are correct before emailing the form off. I am so confused and I don't want it to put a damper on our excitment of placing our first cache. So what do I do about accuracy and the 14 feet issue? Would anyone have kind words for me Thank you in advance! Dawn Quote Link to comment
+wavector Posted January 12, 2009 Share Posted January 12, 2009 Hey Fellow Cachers A newbie here - with (Proudly) 81 finds under her belt Okay, so I'm finally getting enough confidence to hide my own. I got everything we need to place it - and tried to do so this weekend, and we hit a BIG bump! Accuracy? I just don't understand what we did wrong or if it was out of our hands. You mark an area, and then put it as your waypoint and you should be able to get relitively close to where you marked, right? But we also noticed, our accuracy on our gps was 14ft. How in the world do you hide a cache with 14 feet accuracy and expect other people to find it? My husband and I spent OVER 2 hours trying to hide a cache. Yet, when we marked our car, it brought us back to it just fine. So what do I need to consider? Telephone lines, tree canopy's, what else? I just can't hide it in an open space. My fear is hiding this cache and nobody being able to find it. I've read and researched, and they all say to mark it quite a bit of times to make sure your coordinates are correct before emailing the form off. I am so confused and I don't want it to put a damper on our excitment of placing our first cache. So what do I do about accuracy and the 14 feet issue? Would anyone have kind words for me Thank you in advance! Dawn 14 feet is fine, that is plenty close. One thing to avoid is taking your mark shortly after you have stopped walking. The best mark is going to involve a little time at the site allowing your GPS to record an accurate set of coords. You can get a good mark by taking one just as you stop at the point you are hiding the cache. A poor mark is obtained by walking up to spot and then stopping and then after you have stopped for 10 or 15 seconds taking your mark. You can actually watch the accuracy and the coords drift off and then come back after you have stopped moving for awhile. The whole idea is to put away your GPS once you get close so 14' is good enough accuracy for almost any seeker. Taking coords at different times of the day can help refine the accuracy, satellite geometry plays a part in establishing location accurately and I have seen geocaches where the coords actually wander around through the day, at 2:00PM you are pretty close to ground zero and by 7:00 PM you are off 20'. People will inevitably offer more coords in their logs if yours are suspect (even if they are not!). Quote Link to comment
+BrrrMo Posted January 12, 2009 Share Posted January 12, 2009 Hey Fellow Cachers A newbie here - with (Proudly) 81 finds under her belt Okay, so I'm finally getting enough confidence to hide my own. I got everything we need to place it - and tried to do so this weekend, and we hit a BIG bump! Accuracy? I just don't understand what we did wrong or if it was out of our hands. You mark an area, and then put it as your waypoint and you should be able to get relitively close to where you marked, right? But we also noticed, our accuracy on our gps was 14ft. How in the world do you hide a cache with 14 feet accuracy and expect other people to find it? My husband and I spent OVER 2 hours trying to hide a cache. Yet, when we marked our car, it brought us back to it just fine. So what do I need to consider? Telephone lines, tree canopy's, what else? I just can't hide it in an open space. My fear is hiding this cache and nobody being able to find it. I've read and researched, and they all say to mark it quite a bit of times to make sure your coordinates are correct before emailing the form off. I am so confused and I don't want it to put a damper on our excitment of placing our first cache. So what do I do about accuracy and the 14 feet issue? Would anyone have kind words for me Thank you in advance! Dawn I don't think 14' is that bad, but I only have 51 finds. JMO One of the best pieces of advice I have had was get close then look for it. A little experience and people will know what to look for. BrrrMo Quote Link to comment
+StarBrand Posted January 12, 2009 Share Posted January 12, 2009 The General accuracy of our handheld units is in the 20 - 25 foot range. You just can't expect that to be very much better. The accuracy reading on your unit is actual what is called an EPE reading. Estimated Postion Error. It should be read something like "I estimate the actual coordinates of this spot are within 14 feet of the reading being displayed approximately 60% of time or better under the current sat strength and geometry and number of signals". Many websites say to get the actual error up to around 90% confidence - you would have to double the error reading. Fourteen foot is pretty darn good and no reason for concern whatsoever. Quote Link to comment
+tozainamboku Posted January 12, 2009 Share Posted January 12, 2009 The value you see is Estimated Position Error (EPE) which is not quite the same as accuracy. It is basically stating how much of an error you can expect. Different manufacturers define this differently. Essentially it means that some percentage of the time you can expect the true position to be less than that distance away. This also implies some percentage of the time the error will be more, and for some small percentage it can be significantly more. That means that if you really had a clear view of the sky and took several readings over time you can be reasonably confident that you have coordinates much closer to the true position than what the EPE says. On the other hand if there is something interfering with your units ability to "see" the satellites and you just quickly grab the first coordinates your unit gives, you have a small chance that you will be a lot farther away than the 14 feet your unit says. If you have EPE of 14 feet and take several readings and average them (or if your unit can do it, allow it to average over a period of several minutes) your coordinates will be fine. Quote Link to comment
+Jim och Tora Posted January 12, 2009 Share Posted January 12, 2009 Hi there! Many GPS's have a feature that let you "average" the spot when you mark it... this actually takes a reading of the same spot a bunch of times (usually 20-40 will do the trick) and then give you the average reading. This often helps "average out" the error. 14 feet (4-5 meters) is actually a very good margin of error. As you have figured out, in cities, thick woods, under metal bridges, tunnels etc this error margin would be enviable! As you are new to caching, a little tip.... you can count on the average error for the placer of the cache to be about 5 meters (15.5 feet) in open terrain or light woods. You should then add the margin of error shown on your GPS to the placers margin... in otherwords, if you are standing at "0" and your GPS is showing a 14 feet error and you add the average error for the placer( 14 feet), you can reasonably expect the cache to be within about 15-28 feet of your position (In a circle with a radius of 28 feet) After a little experience, you will find that this is actually close enough and as your "caching eyes" develop you will often see the cache as you are walking up to the 0 point. Happy Caching Quote Link to comment
+Jim och Tora Posted January 12, 2009 Share Posted January 12, 2009 Hi there! Many GPS's have a feature that let you "average" the spot when you mark it... this actually takes a reading of the same spot a bunch of times (usually 20-40 will do the trick) and then give you the average reading. This often helps "average out" the error. 14 feet (4-5 meters) is actually a very good margin of error. As you have figured out, in cities, thick woods, under metal bridges, tunnels etc this error margin would be enviable! As you are new to caching, a little tip.... you can count on the average error for the placer of the cache to be about 5 meters (15.5 feet) in open terrain or light woods. You should then add the margin of error shown on your GPS to the placers margin... in otherwords, if you are standing at "0" and your GPS is showing a 14 feet error and you add the average error for the placer( 14 feet), you can reasonably expect the cache to be within about 15-28 feet of your position (In a circle with a radius of 28 feet) After a little experience, you will find that this is actually close enough and as your "caching eyes" develop you will often see the cache as you are walking up to the 0 point. Happy Caching Quote Link to comment
+JohnnyVegas Posted January 12, 2009 Share Posted January 12, 2009 Hey Fellow Cachers A newbie here - with (Proudly) 81 finds under her belt Okay, so I'm finally getting enough confidence to hide my own. I got everything we need to place it - and tried to do so this weekend, and we hit a BIG bump! Accuracy? I just don't understand what we did wrong or if it was out of our hands. You mark an area, and then put it as your waypoint and you should be able to get relitively close to where you marked, right? But we also noticed, our accuracy on our gps was 14ft. How in the world do you hide a cache with 14 feet accuracy and expect other people to find it? My husband and I spent OVER 2 hours trying to hide a cache. Yet, when we marked our car, it brought us back to it just fine. So what do I need to consider? Telephone lines, tree canopy's, what else? I just can't hide it in an open space. My fear is hiding this cache and nobody being able to find it. I've read and researched, and they all say to mark it quite a bit of times to make sure your coordinates are correct before emailing the form off. I am so confused and I don't want it to put a damper on our excitment of placing our first cache. So what do I do about accuracy and the 14 feet issue? Would anyone have kind words for me Thank you in advance! Dawn Go ahead hide your cache. Quote Link to comment
+Sandy Hams Posted January 12, 2009 Share Posted January 12, 2009 Ditto to all the previus posts. Most commonly used handheld units have an accuracy of 20-25 feet, so 14 feet is great -- best you can expect. When we hide a cache or check coordinates on a cache we place the unit at the spot, set it down and set it to average coordinates. We then take a reading of perhaps an average of 10-15. Seems to work great. We also each (two of us) have a unit so we will both get coordinates and compare -- usually the two units are within 1 or 2 numbers of each other. Quote Link to comment
K-9Patrol Posted January 14, 2009 Share Posted January 14, 2009 Hello. As a very new geocacher, I've no buisness giving advice to others. But I'll throw in my 2 cents. I'm using an old Rino 110. It seems to be extremely accurate. So far, when my GPS says 0, then the cache is almost right at my feet. Even knowing this, I've noticed that I routinely put the unit in my pocket at around 10-15 feet and start eyeballing the area. I find that to be part of the fun. I personally don't want to end up right on top of the cache. I enjoy searching the immediate area after a hike. Again, just my 2 cents. Your 14 feet seems ok to me. Quote Link to comment
+michigansnorkelers Posted January 14, 2009 Share Posted January 14, 2009 Don't worry! This IS a treasure HUNT after all. What fun would it be if our GPSr units had one inch accuracy??? Might as well set a flag up over the cache!!! Honestly, aren't you a just a bit disappointed when your GPSr (appears to) takes you directly to the cache and you find it immediately ... or see it from 100 feet away? So, don't worry about 14 feet accuracy. On the other hand, I sometimes DO get a little perturbed when I have to expand my search radius to over 50 feet, depending on the circumstances. Happy Geocaching! Quote Link to comment
+briansnat Posted January 14, 2009 Share Posted January 14, 2009 (edited) So what do I do about accuracy and the 14 feet issue? Nothing. As others have said 14 feet is quite good. Besides how much fun would this be if the GPS brought you directly to the cache every time? My husband and I spent OVER 2 hours trying to hide a cache....I've read and researched, and they all say to mark it quite a bit of times to make sure your coordinates are correct before emailing the form off There is no need to do that. If you have good sat alignment and reception at the spot you just need to take one reading. If you have bad reception or sat alignment you could take a hundred readings and still not get good coordinates. In the past I just made sure I had a good signal, let my GPS settle at the site for about a minute, took one reading and went with it. Now that I have a GPS that waypoint averages I let it average for about 2 minutes, then use that. I've placed over 250 caches and usually get compliments about my coordinates. I'd say I've had complaints about maybe 10 caches and in no case did the coordinates prevent people from finding the caches. So there is no need to spend more than a few minutes getting your cache coordinates. If by chance they are bad then just go back and try again but odds are you won't have to. Edited January 14, 2009 by briansnat Quote Link to comment
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