I need GPS or surveying help in finding property markers

July 22, 2009 5:52 PM

Any map/orienteering/surveying experts in the MetaHouse today? I need help finding my property markers.

I'm trying to find the property markers for my rural land without success. The only one I've found is on the neighbours property. If you take a glance at that link, you'll know why I can't/won't go ask the neighbours for help and that I don't want to go onto their land to find intermediary posts.

I have this map: landmap-small2 (change the URL to landmap-small.png without my notations, or to just landmap.png for a 440k monster). Can I go from the one GPS coordinate I've listed to get GPS coordinates for all of the dots that I've marked with a blue & red bullseye? Simple to do? Can you help me do it?

Thanks in advance!

posted by Kickstart70 to Science & Nature (12 answers total)

I'm no orienteer, but can you measure the horizontal and vertical distance between points on your map and use trig to get the angle and distance you must walk from the start? Then its just a matter of using a compass for the angle and measuring distance walked, which I'm sure your GPS unit can do.
posted by jordanlewis at 5:58 PM on July 22, 2009

Well, there's no guarantee that there are physical markers anywhere on your property. And they don't really matter, anyway. Legally, the recorded deed on a piece of property like this usually specifies a series of coordinates starting from a single known reference point (not on the property itself), so if there is a legal dimension to this, keep that in mind. But (and apologies if you know this much already) the numbers along each line are bearings and distances. The bearings are given E or W of either N or S based on context, so for instance the line at the north end of the cul-de-sac is given as 66d21'50" 23.715, which means walk 23.7 feet in the direction 66 degrees E of due N. You can follow each line in order to walk the property boundary and find whatever markers there might be; all you need is a compass and a long measuring tape or a steady stride.
posted by Chris4d at 6:20 PM on July 22, 2009

sorry, not cul-de-sac. bend in the road. anyway.

Oh and since you're in canada, some conventions may be different than here in the US. Looks like all of the angles might be measured from due N, instead of N or S.
posted by Chris4d at 6:29 PM on July 22, 2009

If there are markers, they have a metal core. A metal detector is the necessary tool.
posted by yclipse at 6:35 PM on July 22, 2009

Chris4d is in a western state. Here in the midwest, a land description such as he describes might read: "Go North 66d21'50" East for a distance of 23.715 feet" To turn around and retrace your steps, "Go South 66d21'50" West for a distance of 23.715 feet".
posted by yclipse at 6:41 PM on July 22, 2009

The NGS has an online utility that you can use to forward your GPS coordinates. There is also an executable you can download here, but I would use the online version. The Azimuth is the angle of the line clockwise from North, and the distances are metres. Keep in mind the azimuths may not be the same as on the map, make sure the direction makes sense.

Let me know if you need more explanation.
posted by Yorrick at 6:58 PM on July 22, 2009

The annotations IP on the metes and bounds you have should indicate the presence of an iron pipe. Be aware that these can shift or be moved, or removed, but hopefully there is something out there to find. Sometimes you'll see IPS or IPF which means set or found respectively, but since this doesn't indicate they were presumably set at the same time the survey was performed.

I don't know what the OCIP means. The other comments on how to read the information is right now.
posted by meinvt at 6:59 PM on July 22, 2009

1. Plain consumer GPS will not work well for this type of small scale work, as foliage, your body's shadow, etc, will continuously change the satellite constellation and lead to small errors. Even long wave DGPS is hit or miss.

2. The key to finding these markers is going to be this: When you locate two known markers, this gives you a baseline with a known azimuth. You can use this azimuth to estimate the direction of any of the other markers.

3. This type of tight work is usually done with a transit and a tape measure or laser rangefinder (modern companies will use much more complex gear). You probably don't have access to this, but you need this functionality. What I recommend is get a decent size protractor ($5 or $10 at an art supply store) and a portable card table. Put it level on top of one of the markers and draw out the angles on the surface or on a large piece of paper taped to the surface. This lets you measure out the angles and project angles in new directions, and actually see where the other markers are.

4. If you have problems with finding distances, there are javascript utilities that will let you compute a distance across multiple segments with different angles. If this gets too confusing, just work it out with direct measurements on the plat with a ruler and protractor.

5. As others said, the pipe may be buried. Be prepared to have a metal detector ($25 for a children's detector, which works fine), or get a hoe and try a little light plowing to see if it turns up.
posted by crapmatic at 7:19 PM on July 22, 2009

(addition to #3 -- Use a 4 foot board to sight along these angles you draw on the card table, as a sort of poor man's transit)
posted by crapmatic at 7:20 PM on July 22, 2009

Regular GPS isn't accurate enough for property markers. Try going out to the same site multiple times and you'll see why.

Depending on where you live there may not be any permanent markers on your property (we don't have any here) but if you have them the easiest ones to find will usually be out by the road or by another clear landmark like a creek. It may be a pipe on your property line or a nail hammered into the driveway/ sidewalk, depending on how and when the area was subdivided.

Also if it was surveyed before the roads and driveways went in there's no point in looking for the markers because they are history.

You might also try calling the survey company and asking them if they put permanent markers before spending a bunch of time looking for them.
posted by fshgrl at 8:24 PM on July 22, 2009

Map and compass might not even be accurate enough for finding property markers, if they're even present, unless you know where at least one on your property is. Frankly, the error even with experienced users of the most accurate military orienteering compasses is a few feet in any direction ... even when dealing with distances as short as 20 or 100 feet. Likewise, a normal GPS will have an accuracy bubble of about 5 feet to 10 yards depending on satellites and other things.

See above where people explain how to read the figures... good luck, though, because you're looking for a needle in a haystack.

Don't forget, in Canada, that you need to account for the difference between polar north and Magnetic north if you're using a magnetic compass.

I think the real answer is probably going to be to hire a survey company who can come out and do it. Alternately, see if a school/college in your area has a surveyor training program and might be willing to help you out in return for some real world practice for their students. Around here, they generally train on city road construction projects.
posted by SpecialK at 10:48 PM on July 22, 2009

It depends on your purpose and how accurate you want to be. If you just want to know then sure, use GPS. If you want to build anything then hire a surveyor. You can use the neighbor's iron pipes to measure off without entering their property so I don't know why that would be an issue. The surveyor would use those regardless. Depending on when the map was from, the pipes should still be there. Pipes can easily be found with a metal detector and typically are at grade or at worst an inch or so below grade. A rough guide to finding property lines is looking for utilities like phone poles, power poles, etc which typically are placed on property lines.
posted by JJ86 at 6:21 AM on July 23, 2009