I'm using a Garmin 60CSx, Garmin 24K Southwest Topo Map, Google Earth and the way points from the Arizona Massey and Wilson book.

Which is more accurate, Google Earth or the Garmin Topo map?

The Wilson book and their GPS way points always seem to be 175~250 feet off when I compare them to the trail as seen is in Google Maps.

So, how would you GPS Gurus plot a course? Would you take the way points and plot them on Garmin Maps, then adjust them to align more with the trail as shown in Google Earth?

I know these units will never be dead on, I'm just trying to get the way points as close as I can get them to the actual trail on either Garmin or Google Maps.

Thanks!!

_________________
'06 Jeep KJ Sport... w/some stuff
'08 Jeep JK X... w/more stuff

It's an AZ LOST JEEPS thing....
other folks don't understand!!

My gut feeling is that the Topo map would be more accurate, but in this day and age, it's possible that both are reasonably accurate. I guess I'm not really sure what you're trying to do. What is your goal by taking the plot points and adjusting them back to google maps. Are you trying to create a presentation to show others your route?

_________________
-=Stock, but goin' places=-

04 3.7 Sport.
Auto Trans
Yokohama Geolandar AT/S 235/70/R16
Garmin GPS on RAM Mount

Mileage Trend:

In the past I have used Google Earth to plot out waypoints and routes, then I save everything as a .kml file from GE and use a free program called GPSBabel to convert the .kml file into either a .gpx (xml-based file that can be opened by many various programs) or .gdb (Garmin specific file).

Thanks for the info Kevin about the files.

So, I can assume that plotting a course actually viewing the trail on Google Earth and placing a waypoint is better than plotting a course using Massey's waypoints alone which always seem to be off 175~200 feet??

Again, thanks.
AJ

_________________
'06 Jeep KJ Sport... w/some stuff
'08 Jeep JK X... w/more stuff

It's an AZ LOST JEEPS thing....
other folks don't understand!!

Just stumbled onto this thread. This information might help you make sense of what's going on: The Massey & Wilson GPS points are actually very nearly dead on. The problem is they use an older map datum, NAD27, whereas Google Earth uses WGS84. Most GPS units are also set up to use WGS84 by default. Whenever you're working with GPS coordinates, you need to be sure that you know what datum is being used.

Here's an online calculator that will convert NAD27 coordinates TO WGS84 (the calculator actually converts from NAD27 to NAD83, which for our purposes is virtually the same as WGS84): http://www.ngs.noaa.gov/cgi-bin/nadcon.prl

Here's a screen shot from my GPS software that shows the difference, using a waypoint from one of the routes in Massey & Wilson's Southern California book. The spot marked on the right is what happens when you input the Massey & Wilson waypoint without converting it to WGS84. (It's supposed to mark the turnoff from the paved road to the dirt track.) The spot on the left is the same waypoint converted to WGS84 (right where it's supposed to be).

Thanks. I set the correct formate on my maps and in my unit, still many times the distance is when the Mapsource is viewed in Google Earth.

Now my 60csx has developed a problem... sometimes it starts to track backwards and the electronic compass goes dead. According to Garmin, all I have to do is recalibrate the compass and it should work. It didn't. The unit decides when it wants to start tracking correctly again. This is the 5th trail (3 in AZ, 2 in CO and 1 in UT) that it's done it... I'm calling Garmin in the AM either for a re3pair work order, but preferably an exchange foe a new unit.

_________________
'06 Jeep KJ Sport... w/some stuff
'08 Jeep JK X... w/more stuff

It's an AZ LOST JEEPS thing....
other folks don't understand!!

That stinks that you're having trouble with your Garmin. I haven't used Garmin in a long time, I just had a bare-bones Etrex back when handheld GPS units were a new thing. Never had any problems with it. I use a DeLorme PN-40 now. It's really cool.

I don't quite understand what you're saying about viewing Mapsource in Google Earth. Looks like a word got dropped. I think you mean the distance is OFF? But is it the Garmin map that's off, or is it the route that you've plotted from the Massey waypoints? When I convert the Massey waypoints using the link I posted, they show up just where they should in Google Earth. Your GPS and your maps should be set to WGS84, just like Google Earth. But the Massey waypoints need to be converted with that calculator in order to show up accurately.

_________________
2002 KJ (un)Limited 4x4: OME HD lift, ARB bullbar, Warn 4X flood lights, Skid Row tranny skid, Mopar engine, transfer case and fuel tank skids, Boulder Bars, 245/75/16 Goodyear Duratracs on Moab wheels.