Setting Up Your GPSr
The primary screen I use for finding caches is the "Map" screen -- the Map may be called the Plotter on some units. Almost all units have a screen that looks like a compass. This "compass" will point toward the cache. I don't care for the compass display. As you get close to the cache your display becomes more important -- that's exactly when this compass starts spinning, reversing and in general goes nuts. (Some more GPSrs have built-in 'electronic compasses.' I'm not talking about them -- what I'm talking about is a mock compass.)
My unit has another screen that's supposed to look like a highway and I guess you're expected to try to walk on the highway to get to the destination -- phhhht!. (Is that how to type a raspberry sound?).
My unit has a fair degree of configurability, so I hide the compass, the highway and a couple of other screens I don't use for geocaching and don't want to have to leaf through to get to the screens do I use. I only use three of the available screens. It's fun to check your speedometer against your GPSr's speed reading about twice, then that screen's just in your way. The Map screen is the one in the Figure below. The two other screens I check occasionally are the one that displays the current coordinates (called the "Position" screen on my unit), and the one that shows your satellite pattern and signal strength ( it's called, appropriately enough, the Satellite screen, and on mine it also shows battery condition). On the Garmin the current coordinates are also shown on the Satellite screen.
Most units have an alarm to alert you if you've lost satellite data. Be sure it's turned on so you don't find yourself following bogus readings.
Be sure your Map Datum is set to WGS84
Next, if your unit permits, configure the data displayed in the boxes at the bottom (or top on some units) of the screen (see the Figure). Most units let you put almost anything you want in these data boxes. On the Map screen I show the distance to the cache -- this is most important. In the other box I show the EPE (Estimated Position Error -- Garmin may call this "GPS Accuracy"). The EPE gives you a feel for how much your position readings (lat/lon) may be in error. [For a more complete explanation of EPE Click Here.] On the Position screen I show the EPE again, and the Bearing Note1 -- I'll explain why later. But, for now you need to set your GPSr's north reference to "Magnetic North." [Note: Some offset/multi caches require you set it to True North -- read the instructions for such caches which use Bearing carefully. After you've finished a cache that uses True North switch back so your unit is normally set to Magnetic North.]
Finally, you have to make a configuration change to the Map screen to set the black arrowhead so it always points in the direction you're facing (see Figure below). On Magellan units the default has the arrow always point north. This means it's constantly changing -- that hurts my mind. [I think some Garman units have a little walking man where the arrowhead is and I think it comes set correctly.] Finally, I select the options that set the Map detail to Low to minimize the stuff shown on the Map screen. If you don't do this it can be cluttered making it more difficult to use. If there were a way to turn off everything except what's shown in the Figure I'd do it, but I haven't found a way to do this.
Traveling To The Area
You may want to paint it so it will be easy to find when you drop it in the leaves. I've spent far too much time looking for it. And, I've had to make six of them because I couldn't find the one I dropped in the leaves. My latest is painted with apple red fingernail polish. Update: Now I've lost it.
Sometimes you find yourself in a place where you can't move around at random to do the distance dance. In dense undergrowth for example. In that case you may have to resort to the Bearing and compass method. Now we're talking about a real compass -- one with a swinging magnetized needle that points north. I don't find a compass of much value and rarely use it, unfortunately there are times . . . [Update: I use my compass more in the woods as time passes.]
For just such times, I show Bearing on the Position screen.
For your GPSr to work with a compass it needs to be set to Magnetic North. [It's
beyond the scope of this article to explain how to follow a bearing using
a compass, and I didn't find a good article on the web.] Bearing is
the angle between north and the cache. Point one arm toward north
and the other toward the cache -- the angle, measured clockwise, between
your arms is the
bearing of the cache. The GPSr gadget knows the bearing
whether you're moving or not. By entering the bearing shown on your GPSr
on a compass, then orienting the compass to North it will point toward the
cache coordinates. You can simply walk a little way toward the coordinates and repeat this on a trial-and-error basis to
move closer and closer to the coordinates, or you may want to try this "triangulation
technique." When using this method, I flip over to the map screen
occasionally to see how far I am from the cache.
|Sidebar -- True North vs
The question of which setting you should use is asked regularly in the Getting Started Forum at gc.com (geocaching.com). First, this setting has nothing at all to do with classic geocaching. It has to do with compass readings, not latitudes and longitudes. So, whether you set your GPSr to True or Magnetic north makes no difference whatever in finding a cache using Lat/Lon.
It's used occasionally in "offset" or "multi" and maybe mystery/puzzle caches. Usually to "project" a waypoint. Projection is beyond the scope of this article. It's also used in conjunction with a compass under certain difficult field conditions -- See triangulation technique mentioned just above this sidebar.
Compasses use Magnetic North -- not True North. Maps use True North. Some people will say "My compass reads True North." They're just confusing the issue. You can make a compass read true north, but this involves making certain adjustments for your particular location based on a factor called declination. And, this factor (and thus the adjustment) is different for every place on earth.
The bottom line? In my opinion, set your GPSr to Magnetic North until told by cache instructions to do otherwise, then set it back when you're done. If you intend to use maps a lot with your GPSr, set it to True North. There's much difference of opinion on this. If you want to read more about the subject go here and here.
Good luck and if you found this article useful email me.
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