SURVEY0R

Thanks for catching that Poindexter. Seems I created a new datum there....

Not sure what your intentions are.... It is possible to calculate rough Lat/Long or UTM coordinates for a section using USGS Quadrangle maps (1:25000 series), but it sounds to me as if you are trying to locate the property corners of a parcel with handheld GPS, and that does not work as it is not accurate enough. If you are trying to use GPS just to go to it, then using a Quad Map or a website such as TOPOZONE.com will get you in the ballpark. Use UTM coordinates instead of D/M/S, as it will be more accurate. (Note that coordinates given on USGS Quadmaps are on NAD29 Datum - NOT NAD83) If you are trying to locate a parcel in the hopes of calculating a boundary or something along those lines, consult a local land surveyor.

Just a few notes about coordinates and datums... The NGS data sheets give 3 types of coordinates: - LAT/LON in D/M/S - State Plane Coordinates - UTM (Universal Transverse Mercator) It should be noted that these coordinates are adjusted to the NAD83 datum. If you are scaling coordinates off of USGS Quadrangle maps or off a website such as TOPOZONE.com, these coordinates will be on the NAD29 datum. If you are using Lat/Long in D/M/S, the difference between NAD83 and NAD29 (in my area) is a grid shift of approx. -750' in the Northing and +10' in the Easting. (This could be why you are not finding anything) Set your datum in your GPS unit accordingly. Another thing, locating coordinates using D/M/S is not very accurate. One second of Latitude = 109'. Puts you in the ballpark, but you have a large search area. (Another reason why you may not be finding anything) I find that using UTM is a more accurate system. UTM is in meters. 1 meter = 3.281 feet. Most GPS receivers w/ WAAS enabling say that the positional tolerances of their units is <3 meters. I can verify this as I have been averaging about 1.7 meters [or approx. 6') to known NGS monuments. Again, if you use USGS Quad maps or TOPOZONE, and you want to convert the coordinates from NAD29 to NAD83 - here is a link to CORPSCON, the Army Corps of Engineers computerized toolbox to convert datums and coordinate systems. http://crunch.tec.army.mil/software/corpscon/corpscon.html Don't sweat it. It took me a couple days to figure out the datum shift myself. Good luck, and let me know how it goes. [This message was edited by SURVEY0R on February 06, 2003 at 07:27 PM.]

So I pick up a handheld GPS unit thinking that it would be handy in finding section corners and benchmarks deep in wooded areas. (Not to take away from the art of traditionally locating these monuments, but hey, time IS money) My first test to verify the positional accuracy of the unit was to input the coordinates of a NGS station and to go look for it. I got wood when the unit put me 5 feet away from it. And then I found this site. Good luck in your searches, ladies and gentlemen. I'll be out in the field if you need me.