Basic Navigation Question

[+MnStar]

New to using a handheld gps. I have used a map and compass many times before, in the military and for rec. use. I never had a problem figuring out how to get from point a to point b. I was a radio operator in the Marines and called in fire missions for an artillery unit. So I know a little bit about land navigation.

 

I recently bought a Garmin Venture CX, tried it for a couple of days and took it back. Primarily because I found the controls hard to use, and when I went after my first cache it tried to take me to the middle of a highway instead of the ravine where the cache was supposed to be located.

 

I replaced that unit with a DeLorme PN-20. I like the controls much better, and the software looks pretty sophisticated although it appears to have a steeper learning curve. I'm ok with that.

 

My real question is this: How close is this thing supposed to get me to the target? I keep thinking this would be so much easier with a good topo map and a compass. lol I went after that first cache again tonight, but didn't have enough time to give it a good shot. (It's supposed to be a real easy one) The PN-20 took me to the edge off a pond, then said the cache was directly in the middle of the pond. I didn't think that was likely so I retreated. By the time I got back to my truck I looked at the map on the PN-20 (if you can call these maps) and the track showed that I had been right on top of the cache.

 

WTF?? I can't say I'm impressed. I'm thinking I must be doing something wrong, because people rave about the quality of DeLorme maps, and they do look good on my laptop but on the device (with this tiny screen) it doesn't look very good to me. So now I'm confused.

 

Do I need a good book? Maybe personal instruction? Does this sound par for the course or am I an idiot??

 

Don't answer that last question.

 

Any advice would be appreciated.

[+jbar]

GPS will get you to within 20-30 feet

[+SwampYankee]

They get you pretty close, usually 20 feet and closer. You then need to get into the mode of the hider. Where would I put one of these. After you find a few you will soon think like the person who hid it. Not likely its in the water, althought I have found one there that drove me nuts. Usually on the edge, in a tree, stump, attached to a dock, what have you. Start with the bigger caches, not the small micros. They can hide those very well. Pick easy caches by the numbers they post as to easy or hard. It can be frustrating at first until it all makes sense...Then you can almost walk up on them as your brain shifts to zero in mode.

 

They all give pretty much the same accuracy except with better antenna will get you closer under cover.

 

Thats my 2 cents worth.

 

Swampy

[Neos2]

I agree with what you've been told so far.

 

You can't expect the gps to put you right on top the cache. What fun would that tbe, anyway, right? Any gps will get you to the cache--some do it more quickly or with more style and additonal convenience features.

 

You will get better accuracy with a unit that has a high-sensitivity chipset, like the SirfStarIII chip. It gets a signal inside my house and keeps one under heavy tree cover.

 

You will get improved directional signals from a unit that has an electronic compass. Without an electronic compass, you need to walk at a brisk pace (3 mph is the standard) to keep the pointer in the correct direction. Most of us tend to slow down when we get near the cache.

 

You will get more detail on your maps if you have a unit that has more than just the basemaps on it. Some models will accept additional maps, others will not. Maps are (typically) more important for finding your way to the general cache area than for finding the cache once you get close.

 

The unit you tried first was pretty basic. If you like the one you have now, you should be set now.

[+TurLee]

Have you installed any additional maps or aerial photos? I just got a PN-40 and find the maps and photos are incredible … my other unit just gave me an arrow pointing at the cache, nothing else. And just to be sure, you do know you can zoom in and out on the maps, right?

 

The arrow pointing to the cache is going to bounce around in some spots, particularly in trees. Go where you get a steady reading at 20 to 30 feet or so, keep an imaginary line in your head for that heading, then walk off a ways to a 90 degree angle and see where the new line crosses your first one … that should help you zero in on it.

 

I don't have much experience at this either, but so far my DeLorme has never read more than 6 ft off when I found the cache and I had one at 0.0 and one at 0.1 ft.

 

And like others said, once you find a couple of caches and see what you're up against it does get easier. It took me two tries to find my first cache … when I went back and finally found it I realized that on the first try I had actually sat down for a smoke on the hollow log the ammo box was hidden in.

 

Have fun.

[+SSO JOAT]

I was a radio operator in the Marines and called in fire missions for an artillery unit. So I know a little bit about land navigation.

 

Good. You should give this puzzle a try and next time you're in Alaska you can log it. All the non-military cachers around here have been totally stumped by this very simple puzzle... GC1GP22 It even has all the directions on how to do it hidden all over the page! And still only 1 find with a prosperous audit log.

 

I think you gave up on the Garmin too quickly, though the eTrex units are notorious for poor reception and poor accuracy, the "x" designator is the newer "good" ones. Can't speak specific to your current GPSr as I've never touched that one.

 

Anyhow, just a few general tips. One, go ahead and bring your real compass along. People get too tied up in technology when the "old ways" often work better. Two, the maps in your GPSr are not guaranteed to be as accurate as a paper USGS map. It is quite possible to have the map in the GPSr offset from the real position by considerable distance. This depends on who made the map and what the GPSr thinks the relationship is between that map and what is really on the ground. This brings up point three... check your map datum! If your GPSr is set to the default WGS-84 map datum, yet your map is based on an NAD-27 survey, you can be off by a couple hundred feet! The reciprocal can also be true if your GPSr is inadvertently set to something other than WGS-84. All geocaching.com waypoints are provided for WGS-84 and the majority of electronic maps are also in that format.

 

Next, use the map to get to the general area, but not to hunt the cache. When you are in the right area, make sure you have a good GPS lock. Your GPSr should give an error factor (EPE) based on current satellite reception. This ought to be less than 20 feet if you have good signals. Now look at the cache waypoint. It should tell you a distance and bearing from your current position. With those numbers, go ahead and use your good old fashioned land navigation skills to take a compass bearing, estimate the distance, and get a visual on the cache waypoint. Note that the cache waypoint is not necessarily the exact location of the cache. The cache hider probably didn't get "perfect" GPS positioning either, so that spot is still subject to a roughly 30' error factor.

 

Now that you have a bearing on the spot, go there. When you're on the spot, use your GPS to verify (if the hide isn't already apparent). Forget about the map features now. You should have a lock on your own location, and an icon showing the cache. Zoom in as close as the unit will let you. You should be able to see yourself and your relationship to the cache. If you're not within 20-30 feet, then again navigate toward the cache. Remember that if the GPSr doesn't have a calibrated electronic compass, it's not going to "spin" the map to show you which way to go while you're standing still. You'll have to be moving for that to work. Your real compass might come in handy again at this point.

 

Good luck!

[+MnStar]

Hey, thanks for all the advice.

 

This brings up point three... check your map datum! If your GPSr is set to the default WGS-84 map datum, yet your map is based on an NAD-27 survey, you can be off by a couple hundred feet! The reciprocal can also be true if your GPSr is inadvertently set to something other than WGS-84. All geocaching.com waypoints are provided for WGS-84 and the majority of electronic maps are also in that format.

 

I'll give this a try. Obviously still have much to learn. But that's ok. Otherwise I'm forced to sit in front of the TV with my wife.

 

It was a clear sky, no trees or buildings to block the signal. The unit came with maps, so I am using those plus some that I downloaded.

 

BTW, is there a way to make sure the unit is using the detailed maps instead of the base maps? I'm so new to this I don't even know how to tell the difference. I am used to using USGS maps and that kind of detail.

 

Elsewhere here someone suggested hiding a cache and then going back to find it and watch how the process unfolds. That's a great idea, I will try that. I think this could be a lot of fun.....

 

BTW, you know the old saying "close only counts in horseshoes and hand grenades"? Well, that works for artillery too....big time. It was quite a thrill going out with the Forward Observers and calling in strikes when the guns were several miles away. They were amazingly accurate. Of course, it wasn't in combat. I was down in Guantanamo Cuba in the Marines and we did this once a month for practice.

 

Anyway, straying off the topic now....thanks again, all.

[+TurLee]

Assuming the menus are pretty much the same on the PN-20 as the PN-40 ...

 

While on the map display, press Menu, scroll down to Map Setup ... there are lots of options and menu levels there, most of which I am clueless about, but at one point you can check / uncheck the types of maps and imagery to display.

 

Personally, I don't have any experience with maps other than highway maps and the occasional bus / subway route map so I've been using the aerial views at the cache site ... big help to me to see the cache icon in the stand of trees down the third base line of the ball field or in the NE corner of the farm field.

[+MnStar]

Did much better today, although the "easy child's cache" eludes me. Maybe I need a child along to help me!! I was right on top of it, but lots of snow on the ground and hints say it is in the roots of a tree. Will go back and dig another time.

I dropped a red stocking cap, marked it and then walked to the other side of a pond. Coming back to it gave me a real good idea of how this thing operates.

I like it. Now I just have to find my first cache.

[BoatBird]

Just found our first cache today with an old Garmin GPS12- manual input of co-ordinates and no maps.... it was a multi-cache thing with a puzzle to solve to find the cache. First point we approached was by the beach and the clues said we shouldn't have been so then I had to wonder around aimlessly looking for the clue to help us find the cache. Found the clue, worked out the puzzle- and the cache? Was right where my OH ended up first off all with our GPS! And there was plenty of places to hide that thing so we are feeling very pleased with ourselves

[+MnStar]

Hey!! No stealing my "poor me" thread with a find.

[+MnStar]

Ah, the taste of success is sweet indeed. I'm hooked, there's a new sheriff in town.