newbie frustration.

[tim sr]

Just tried last night to find my first cache.

 

Looking on the website, I located a couple of park/grabs near my home and when I got there, the location was no where near where the description on the website said. I am talking a 1/4 mile variance. When I punch in the coord's on Google Earth, they match up with the map shown on the website, but with my GPS, it is not even close.

 

The first one I looked for led me to a public park - right to a tree that was all by itself - exactly to the trunk of the tree...........

 

I have been a user of GPS systems quite a bit for the last 15 years through hunting and fishing, but this does not seem to make sense, as when I punch the coord's into google earth, they match the websites location decsription as well as the map shown.

 

Is his normal, or what the heck am I doing wrong?

 

Tim

[+LEGO]

What type of GPS'er are you using (I have a Garmin eTrex Venture HC)? How are you getting the cache coordinates into your GPS'er? It is possible, if you are manually entering them, that you are making slight errors when entering the coordinates (I have done this myself). What is the identifier (GC#) for the cache that you are having difficulty with?

[+NoHandsGPS]

If you are manually entering the coords into your gps I have to say double and triple check the coords, which I am sure you have already done. A 1/4 mile is a long way off.

[tim sr]

If you are manually entering the coords into your gps I have to say double and triple check the coords, which I am sure you have already done. A 1/4 mile is a long way off.

 

I have a Lowrance H2Oc. I manually entered the waypoints. I checked, double checked, and re-checked the waypoints.......they match.

 

I am wondering if I have an issue with the GPS unit itself. It does not appear to me that I do out on the lakes, as the map data (from a Navionics data chip) seems to jive with exactly what I have seen.

 

The ID of the cache is GC1DFFF

 

 

Tim

Edited August 21, 2008 by tim sr

[+StarBrand]

Be certain you are using WGS-84 as the datum and decimal minutes as the coordinate format.

[tim sr]

Be certain you are using WGS-84 as the datum and decimal minutes as the coordinate format.

 

I am not familiar with WGS-84......what does that mean. I double checked - I have it set to decimal minutes........

 

When I use the map chip on a lake, my position and coord's match up perfectly with what the map chip is showing me.....

 

When I go on Google earth, and zoom in on where my GPS took me, I am WAAAAAAAY off where the coord's show on google earth. I must have some dang setting ion my gps skewed......as both caches I attempted were off by .24 miles in the same direction.

 

Grrrr.........

 

Tim

[tim sr]

Be certain you are using WGS-84 as the datum and decimal minutes as the coordinate format.

 

I searching my set-up menu's, I found the map datum set to "provisional S america"

 

The only option for a "wgs" datum was "WGS 1972"........ I am presuming that this is just an earlier version?

 

Tim

 

P.S. Thank you much for the replies......I appreciate it

[tim sr]

Be certain you are using WGS-84 as the datum and decimal minutes as the coordinate format.

 

Found the WGS-84 datum option on my GPS. I selected it. I went outside and saved a WP at the front door - came in and verified it on Google Earth....looks fine! I went and checked my Cache waypoints and they now show different numbers........so I am assuming that was my problem.

 

Thanks a bunch, guys, I appreciate it.

 

Will try again tonight.....

 

Tim

[+JBnW]

One more thing, though. It sounds like your unit recalculated the coords when you changed datums. Make sure the coords are the same as shown in the cache listing...otherwise you'll go back to the same spot as before.

 

Good luck!

[tim sr]

One more thing, though. It sounds like your unit recalculated the coords when you changed datums. Make sure the coords are the same as shown in the cache listing...otherwise you'll go back to the same spot as before.

 

Good luck!

 

yup - it recalculated my coords. I need to be aware of that when fishing now - as I have several waypoints that will no longer be valid........

 

Tim

[+JBnW]

You and I MAY be in the minority here, thinking using a GPS for fishing is more important than for finding caches! But you might wanna do some homework before you get too much farther along to save much hassle (or lost fishing spots) later. Depending on how many fishing waypoints you have, and assuming they were all marked using the same datum, I'd suggest changing your unit back to the previous "provisional S. America" datum (which would re-recalculate the fishing coords back to the way they originally were), and make a copy of those coords (download them to your computer, write them down...however). Then reset the GPS to WGS84, and re-install the fishing coords. Finally, leave the GPS set to WGS84 unless you have a really good reason to use a different datum.

 

Alternatively, you could always keep your fishing coords separated from your geocaching coords, and reset the datum on the GPS as you change activities...but what a risky hassle!

[+JBnW]

Actually, on second thought, we may need to put in a call to the Experts (and then disregard my previous post). If the waypoints were recorded in a different datum, and the GPSr recalculates the lat/longs when changing datums, the old waypoints may still be useable...or at least as useable as when your GPSr was navigating on the old datum.

 

In any event, if you're using waypoints from geocaching.com, you must use the WGS84 datum, or as you found out, LARGE errors are likely.

 

One more thing, welcome to geocaching! Hope you enjoy the search as much as I do.

[tim sr]

Actually, on second thought, we may need to put in a call to the Experts (and then disregard my previous post). If the waypoints were recorded in a different datum, and the GPSr recalculates the lat/longs when changing datums, the old waypoints may still be useable...or at least as useable as when your GPSr was navigating on the old datum.

 

In any event, if you're using waypoints from geocaching.com, you must use the WGS84 datum, or as you found out, LARGE errors are likely.

 

One more thing, welcome to geocaching! Hope you enjoy the search as much as I do.

 

After some monkeying around with it - I verified that my waypoints that were saved under the old datum method were converted intot he new datum format. All is well. No looking last night - too many irons in the fire.

 

Thanks again for the replies.

 

Tim

[+Autorita]

Also: ALWAYS CALIBRATE!

 

I was recently in PA and realised that I had traveled quite a distance from NYC and calibration was necessary. Otherwise, the points I was looking for could be 30' or wwaayyy more off.

 

Happy Caching!