I tried BLM GCDB database coordinates to search for two township corners out in the hills today. I picked the points lat and long from the map viewer, loaded them into the TSC1, fired up the 4700 (navigate to point mode – no RTK base running) and headed out a few miles from town. Hiked in about 400 feet off a dirt road.
I found both corners. At the first the GPS told me I was 20 feet northerly and at the second 25 feet northerly. Both nice cairns with an old marked stone about 6 chains feet apart (one is a closing township corner).
NICE, worked great! Some day (today for me) they won't even need our old hound dog skills anymore, just push the buttons. Anybody with a modern cell phone will be able to do it.
Some of the locations are closer than others, but it is a real handy tool. I loaded a township worth of search pts. in about 5 minutes. Compared to previously found cors. the GCDB coords. were within 50'or so. It depends on the density of found corners the BLM had to adjust to and the reliability of the old survey, but it will get you into the neighborhood.
DJJ
20-25 feet is a little closer than the GCDB that I'm used to in the older survey resurvey areas (1914-1950).
In the original areas it can be hundreds of feet off.
In the newer resurvey (1980-1990) areas within ten feet and in the really new (2000 and later resurveys done with GPS) within three feet but not right on top. You can call the cadastral office and they might give you a Lat., Long. for a new GPS resurvey.
We did that for a 2000 resurvey where they had just buried a corner deep in a field and for some reason the crew couldn't find it with our metal detector (we send it in after that job). With the coordinate they dug it up and we had less than 1 inch between our coordinate and the BLM's. Our control had been tied to three HARN points in a pretty remote area and I don't know how their control was run in but it sure worked. But the GCDB was not on that coordinate, it's a few feet away.
I asked about the new surveys and the GCDB and if I have this correct this is what they do: some computer guy takes the Lat., Long. at the southeast corner of the township that appears on the new plat and then calculates the township using the record dimensions and directions on the plat (nearest .01 chain and nearest minute) so some error builds up as you go northwest.