jrecon Posted May 16, 2008 Share Posted May 16, 2008 help!! new to caching... instead of a gps i use a usgs topo map, protractor, lensatic compass, and my pace count. noticed when i'm plotting the coords given i'm 250 meters n/e off consistantly when i check my work on google maps (topo). made my grids by drawing lines on the blue ticks 1:24 map and using 1:24 protractor.....last minor revision 1994 (it's new) wondering where i'm going wrong? is there a conversion? Quote Link to comment
+Team_CSG Posted May 16, 2008 Share Posted May 16, 2008 help!! new to caching... instead of a gps i use a usgs topo map, protractor, lensatic compass, and my pace count. noticed when i'm plotting the coords given i'm 250 meters n/e off consistantly when i check my work on google maps (topo). made my grids by drawing lines on the blue ticks 1:24 map and using 1:24 protractor.....last minor revision 1994 (it's new) wondering where i'm going wrong? is there a conversion? map datum?? Does your map have UTM or WGS84 layout? Quote Link to comment
jrecon Posted May 16, 2008 Author Share Posted May 16, 2008 map datum?? Does your map have UTM or WGS84 layout? using UTM us datum ticks on corners it's burbank quadrangle 7.5 minute series checked usgs site and it's the latest version...revised 1994 Quote Link to comment
+Cardinal Red Posted May 17, 2008 Share Posted May 17, 2008 help!! new to caching... instead of a gps i use a usgs topo map, protractor, lensatic compass, and my pace count. noticed when i'm plotting the coords given i'm 250 meters n/e off consistantly when i check my work on google maps (topo). made my grids by drawing lines on the blue ticks 1:24 map and using 1:24 protractor.....last minor revision 1994 (it's new) wondering where i'm going wrong? is there a conversion? I have an interest in a nearby State Gameland area. I have two versions of the USGS 7.5 Minute Quadrangle for that area. The older printing has Lat/Long and UTM ticks along the edges. The newer printing has that, plus full length vertical and horizontal UTM grid lines. If you have the newest printing, why don't you also have full length UTM grid lines? The full length grid lines are very convenient to make and take measurements from. However, you should take notice of "1927 North American datum" (older printing), or "North American Datum of 1927 (NAD 27)" (newer printing). Geocaching.com uses the WGS84 Datum. I seriously doubt the difference between them will amount to 250 meters, but you should take it into consideration. I've never used google maps to locate anything, but I think there are mapping location errors on google. If I determine UTM coords (NAD27) by measuring off the map, I can get reasonably close to that spot on the ground by following my GPS. I got within 25 feet of a trail gate on a county line. Close enough for me. Here is an online Coordinate Converter that can handle NAD27 / WGS84 conversions in either direction. No download necessary. Quote Link to comment
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