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Struggling W/ Gear


Geodesik
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Hi all,

 

Given the terrific breadth of experience here, I thought I should turn here first for some help.

 

We're reallly struggling with our GPS. We have a Garmin Legend, and when we're using it, we get a lot of odd results. I guess we're looking for some guidance on how to read the thing.

 

Here's the deal -- when we are in navigation mode, we get to within anout 40-50 feet of the target coordinates, and the distance and direction indicators go wild. Good example -- yesterday, we were getting close when the direction indicator jumped 90 degrees. It wasn't that we were too close -- we were still 40 feet from the target. (We were in scrub trees with clear visibility of the sky. There were a few airplanes overhead here and there, if it matters).

 

Help... we're struggling because we don't feel like we ever get very close to a cache, and its getting pretty frustrating. Any advice appreciated.

 

Brennan

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Perfectly normal! First off, the aeroplanes don't matter a bit. On a really good day, with lots of satellites, spread well over the sky, you're going to be lucky to <3 meter EPE (Estimated positional error); what that means is that you are about there. On a bad day, with only a few birds, or in a poor aspect, your EPE might go up to as much as 30 meters.

 

Once it gets to the point where it's "doin' the dance" it's time to put the GPSr down, and get looking! What I ususally do is triangulate. I approach the position in one direction, and noting the direction and distance that the unit displays and try and pick a mark that looks like about where '0' should be. When the arrow/distance start to go crazy, walk back for a bit, and then approach from 90 deg to your last one. Note the brg/distance, and try and find your mark from the first run...

 

Once you're reasonably sure that you're in the area, start looking. Especially for traditional caches, look for things that aren't quite 'right'. A pile of sticks that just wouldn't fall like that, some rocks piled up etc.

 

If you can, make your first few hunts fairly simple, 1 or 2 star difficulty, so that you can get some exposure to the different types of ways that people hide them. Best of luck and welcome to the addiction hobby!

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TiredIron's reply is a great explanation. Another thing that I would point out is that GPS readings seem to be more accurate when your moving. So when you stop and look or stand still the GPS is almost for sure to start doing its dance. I do exactly what TiredIRon does by triangulating where it might be. IE as I walk towards it and it says 40 feet ahead I'll picture that spot ahead. Then walk to 90 degrees of where you were and start walking at the spot again. Two or three times of this and you should have a very close idea of where it is. When I'm signing the logs I almost always set my Garmin Legend down on the container as I write. When it finally settles down I usually have readings from 30 feet to 7 feet away. I've yet to see it read 0.0 but I wouldnt expect it to either.

Good luck...

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Also ....

 

Hold the unit flat in front of you and don't hover over it.

 

Walk slower as you get nearer and let the unit "settle down" a bit.

 

Don't just keep wandering aimlessly chasing the "Go To" arrow. When I'm down to the last 100 feet I'll slow my pace, make note of which way is North, start looking for good hidey holes. When I'm stymied I'll set the unit down in a prominent location and let it sit for a minute or two and then check the distance and direction.

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And more on letting the GPSr "settle down". The distance, bearing, and EPE will fluctuate for a while as the unit gets more readings, avergaes them out, and gets a better lock on your position.

 

A technique I've used when my arrow starts goin nuts is to stop, put the unit down, and let it "settle down" for a couple of minutes. Then I'll pick it up and take 3-5 deliberate paces in a straight line, pause again, and see where the unit tells me I need to go next.

 

Sometimes we get in a hurry to find the target that we simply don't give the device time to keep up or catch up.

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Another trick is to switch to the satellite page when you are close and note your current long. and lat. Walk as needed to make the current reading match the coordinates of the cache. I have found that the coordinates tend to jump around a lot less than the arrow.

 

This still won't get you dead on to the cache. If your epe is 20 feet, and the hider's epe was 20 feet, there is going to be some variance. As noted above, when you get close, stop looking at the GPSr and think, "Where would I hide this thing?"

 

Welcome to the recreational activity/sport/hobby.

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I use the trip computer page, and have the distance, bearing, and heading displayed. I just match the bearing (the direction to the cache) and the heading (the direction I'm moving) and keep making the distance decrease. When I get within 50 feet or so, I stop and take a look and see what is about 50 feet away and in the right direction, and go there and look. The arrow, or navigation page, is useless to me, because it's so variable. I never use it. But whatever works for you, just be aware that the GPS isn't accurate to a foot or so, and if you get within 30 feet or so, just start looking for a place that looks like where a cache would hide.

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Thanks so much, everyone! We really appreciate getting some tips like this. It's great to know that we A) aren't stupid, ;) Experiencing things it sounds like a lot of folks have tackled. I'd never thought about the 90 degree thing, but that makes a ton of sense. Thanks everyone!

 

Brennan

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The GPS doesn't align the arrow like a compass does. It aligns from where you were to where you are now only if you are walking in a straight line for 20 feet or so. If you stop or walk in a tight circle the poor arrow doesn't know what to do. It's best to pretend you're steering a continuously moving torpedo into your target with only gentle turns as you walk forward. If you mess up walk 50+ feet away and then start back...As soon as the arrow aligns to your direction of travel steer it to the cache while continuously moving. If You have heavy tree cover try to approach the cache from different directions. This works. ;)

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Walk slower as you get nearer and let the unit "settle down" a bit.

 

Actually this is one of the causes of the problem. Because the Legend doesn't have a magnetic compass, you need to be moving for it to get an accurate navigation fix.

As people approach the cache they tend to slow down which makes it harder for the GPS to figure out what direction you're moving in.

 

When this happens, I walk back a short distance..maybe 50 feet and approach the area again at a faster pace. This helps "straighten out" the needle.

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Yep. The slower you move, the less accurate the heading is. That's why I don't use the arrow. Traveling 30 mph in your cachemobile, it's relatively accurate. Below about 5mph or so, it's inaccurate, and at 2 or so it's worthless. That's why I want to see bearing, which doesn't change except for the inherent inaccuracy of the GPS position. Slowing down will make the needle move all over the place, but the bearing stays relatively constant.

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My Magellan SportTrak Map has worked really well with the arrow. The arrow has been extremely reliable. Once I get close to GZ (20/30 ft), I just take 10 good paces, stop, do not turn, and look the direction the arrow points. I have been known to do this a couple times when Zeroing in. Of course, we don't have many trees to contend with out here in the desert.

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I use the arrow screen on my ST Pro as well. The nice thing about the Magellans is the Northfinder feature, that's always on on the compass screen. Even when I stop and turn around, I can just line up the sun (or moon) icon with the sun in the sky, and it's right on the money!

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Yep. The slower you move, the less accurate the heading is. That's why I don't use the arrow. Traveling 30 mph in your cachemobile, it's relatively accurate. Below about 5mph or so, it's inaccurate, and at 2 or so it's worthless. That's why I want to see bearing, which doesn't change except for the inherent inaccuracy of the GPS position. Slowing down will make the needle move all over the place, but the bearing stays relatively constant.

Hmmmph. Hadn't realized that. I'll try a few changes on my next hunt. Thanks.

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