Land-Covert Legal Description to GPS
General Topic
Contributors to this thread:
Hunt98 09-Dec-09
playin' hookey 10-Dec-09
Hollywood 10-Dec-09
playin' hookey 10-Dec-09
RobinHood 11-Dec-09
playin' hookey 12-Dec-09
acadianarcher 12-Dec-09
Kevsam 12-Dec-09
surveyor527 25-Dec-09
Hunt98 26-Dec-09
Hellbender 26-Dec-09
nalgi 27-Dec-09
gamedog@gf's 28-Dec-09
gamedog@gf's 28-Dec-09
playin' hookey 28-Dec-09
bill brown 29-Dec-09
paddl-in 29-Dec-09
addicted2elk 29-Dec-09
Gmap4 guy 17-Feb-12
From: Hunt98
I'm looking at buying some hunting land that is not surveyed.

Is there a way to convert the legal description of the land to GPS cordinates?

I am not a surveyor, and I am kind of a cheapskate. A few years ago I got interested in determining the property lines of some mountainous land of my father's. It had been surveyed 8-10 yrs previously, but the flags were all gone. I found an iron stake used to mark a corner, and used my gps to get its coordinates. From they surveyor's plat, which gives compass bearings and distance from each corner to the next, I was able to sit down at home and, using trigonometry and a scientific calculator, determine the gps coordinates of all the remaining corners, even though the property had an irregular shape (ie it was not a rectangle). One thing to keep in mind when using a plat for sloped terrain is that the distances are horizontal and not straight-line, so distance on the ground will be less than on the plat if there is any slope at all. In summary, if you can find one corner and have a plat and understand trigonometry, you can determine the lines with reasonable accuracy, although not as precisely as a surveyor.

From: Hollywood
"distances are horizontal and not straight-line, so distance on the ground will be less than on the plat if there is any slope at all."

...better think that part over.

You are right, Hollywood. The horizontal (plat) distance is the minimum. I got it backwards.

From: RobinHood
playin' hookey

What kind of a GPS were you using? I hope it was a Trimble or some other commercial-grade, sub-centimeter accuracy GPS. If you were using a recreational grade GPS, your accuracy is + or – 10 meters; no matter what “accuracy” the GPS tells you. Starting with that degree of potential error only magnifies itself in your other calculations.

RobinHood, I am aware that much more precision is obtainable with the much more expensive GPS units used by professional surveyors. That is why I acknowledged in my post that property lines determined by an amateur like myself are not as accurate as those determined by a surveyor, and certainly they are not definitive in a legal sense. I disagree, though, with your statement that initial error MAGNIFIES itself in the calculations. Instead, I think the error APPLIES to each calculated corner location. For instance, if the initial GPS reading is erroneous by 10 meters to the north, all calculated corners will be 10 meters to the north of the true corners. While this error is unacceptable for uses such as determining property lines for house lots in a subdivision, or for cutting timber, it was acceptable to me for the purpose of determining where I can use the land for recreation such as hunting, hiking, or camping.

unless your description uses Lat /Long or state plane coordinates you are likely out of luck. Your deed may have magnetic bearings which means you need to know the difference between magnetic and grid north in your area in order to do the calculations

Your best bet is to take a GPS shot at each corner, if you can find them, of the lot. As others have mentioned there can be significant errors in positions using recreational grade GPS receivers but as fas as the positional error there is no way to really know:

you do not know what direction the positional error at each point, it is not constant in size or direction so you could be 5 metres south on one corner and 8 metres north on the other.

YOu can buy a WAAS enable recreational unit which, in my experience, will get you under 5 metres consistently.

As a professional land surveyor and engineer the recreational units are fine(as playing hookey said) to locate yourself on the property but if you plan to cut/mark your property lines or build something near the lines you are playing with fire if you do this yourself.

From: Kevsam
I am a Land Surveyor in Training (hopefully getting licensed soon) and this would be my advice:

1. If you want to get a good idea about the extent of the property you are buying see if you can look at the some GIS maps in the county you are purchasing... maybe a tax parcel map over some orthophotos. These won't be exact, but it most likely wouldn't be that far out of line with anything you would determine with your handheld GPS.

2. If you are serious about buying the property, negotiate with the seller to have the land surveyed. Land is expensive and it is worth every penny to know exactly what you are purchasing.

3. Never use your hand held GPS to determine property lines. There is a reason why doctors are licensed by the state to practice medicine and it is the same reason land surveyors are licensed by the state as well... to protect the public. It is far too technical from a technology standpoint and even more so from a legal standpoint to take that type of liability on yourself.

Handheld GPS can be a great tool for getting you in the right area to search for property corners and that is all. Determining a property boundary is almost never a simple case of mathematics; again legal principles are generally the rule and not the exception... ask a local licensed land surveyor for help or at least tell them your situation and ask for suggestions/options.

Good luck. I hope some of this information helps you reach your objectives.

From: surveyor527
Playin' Hookey: You must be quite a bookworm. With no formal training in the surveying profession, you were able to A) research the land records and find the plat (not that difficult) B) Physically reconnoiter a boundary marker in wooded mountainous terrain (now you begin to need some skills) C) Calculate the difference between the magnetic meridian used on the survey and the State Plane Coordinate System for whatever state you're in (now I've got my eye on you) D) Reduce the magnetic bearings on the plat to field angles, apply them to the State Plane Data and recalculate the bearings of the lines (in State Plane Data E) Use a double meridian distance method to compute latitude and departure and the corresponding coordinates based on your initial coordinate value (wow, are you looking for a part-time job ?) F) Enter these calculated waypoints into your GPS unit and actually navigate your way to them (skill level is dropping here but you could still get in trouble).

Last of all, if you register a GPS point in autonomous or float mode, the inherent error in this is NOT constant as you stated. One point may be off several meters in a northwest direction, and the next point in a different direction.

You'd be better off visiting your County Engineer's office and paying for a color aerial photo with tax map parcels overlaid.

Call a surveyor for an estimate; property is too valuable to just guess. In the current economy, any surveyor in your area would be happy to take on the job and the client is in the driver's seat (partly) in negotiating fees. I have surveyed over 5000 acres in the last few years, all paid for by hunt clubs that had disputes with neighboring clubs or individual hunters, right down to pinpointing existing tree stands! (Farmer Dave gets a free survey of his farm)

Sorry to be so long-winded but I can't stand to listen to a nimrod reduce even our most basic exercise to a few hours on the kitchen table and a $10 calculator. Good Luck!

From: Hunt98
I did contact a surveyor before I posted this thread. He told me the county is not very well surveyed. He said that only "2 of 6" corners are in (whatever that means). He told me he would have to bring in the corners from a ways away.

Does that make sense (or is he feeding me a line?)

He said $25K to do that... $15K in the winter when it is not as busy.

From: Hellbender
Kev-I gotta disagree with your never statement. I use a GPS to rough find boundary all the time and see no issues as long as it is not treated as a survey. For example my bdry is a case in point. Straight lines/corners with a benchmark on the property. Never surveyed and never a fence or painted line. I determined the approximate utms off a a map of corners then did a go to to roughly flag a line in. I then returned to the benchmark with the appropriate declinated compass bearing (cardinal direction)and adjusted any errant flags as needed. i then let the neighbor know I had flagged the property line. He took a look and was in agreement and voila I have established the hunt boundaries of my farm. Whats wrong with that?

From: nalgi
Im a farm and ranch appraiser and I use my GPS all the time to check fencelines and corners. I first plot the corners on a 7.5 Topo map (UTM coord) then drive, hike, ride, crawl to them. This works fine on sections or parts thereof. metes and bounds legals are another matter.

From: gamedog@gf's
Man, I should of been a Lawyer instead of a Land Surveyor. Hellbender, no offense but if you hired a Land Surveyor I can almost guarantee he would establish your corners in a different spot than what you came up with, JMHO of course. Nalgi, fences are nortorious for not being on section lines, ect. I wouldn't risk my reputation or business off a quad map and handheld GPS, IMHO.

From: gamedog@gf's

Sounds like he did the research and there isn't sufficient monumentation for your property. When He says "bring in the corners from a ways away" means that there isn't enough record data in the area and it will be a bitch because he will have to survey the areas outside your property. Depending on the situation He, typically, will have to compile what information there is(deeds, parcel maps and ect, put it into cadd, perform a field survey, evaluate the evidence and then set his corners and file a map (I'm not even touching jr. and sr. rights).

As far as money goes... depends on the area.

Get a couple more quotes.

Gee, Surveyor527, looks like I really got under your skin. I think I acknowledged a couple of times that combining a little high school trigonometry with a GPS to get a rough idea of property lines does not constitute a legal survey. The question in the original post was what I was responding to. I think that if he had wanted to pay a surveyor he would have looked in the yellow pages instead of on this bowhunting forum. Loosen up a little. I'm a doctor, and I don't give people a lot of crap if they try an over-the-counter remedy before seeking medical attention. You really don't have to pay a chef if all you want is a baloney sandwich.

From: bill brown
Don't trust any fence lines to describe your precise boundaries, as the farmer who put the fence in 20 or 40 years ago probably bowed to ease of installation over accuracy of proerty lines. At least, that is what the farmers tell me. If you care, pay to get the survey done.

From: paddl-in
"I wouldn't risk my reputation or business off a quad map and handheld GPS, IMHO" Gamedogger- what am I risking by flagging line w/o a survey? There is no contested line I simply marked the boundary w/o survey which is very common practice in my part of the country. My neighbor agrees to the location of the bdry. Timber harvests hunt rights etc etc are delineated by yes I hate to say it without survey all the time in this part of the world. Or your saying i should drop 10k+ so my neighbor who I am on friendly terms knows where to stop when hunting or fire wood cutting?

From: addicted2elk
surveyor527 isn't getting many clients with that attitude.....

$15k doesn't sound like much depending on what size of property you are talking about and where it's located (rural, urban, etc.). after all, if you're talking about a 5k acre parcel in wooded and mountainous terrain, it could take a long time to traverse around the thing, let alone do all the research at the courthouse and then determine the boundary. monumentation in rural areas is often hard to come by, so it drives up the price quite a bit to go find it and tie your property to that monumentation. so there could be a lot of variables that could make the price go up (or down).


From: Gmap4 guy
I own acreage "North of Paradise" in the Upper Peninsula of Michigan. (Paradise is the local village.) Maybe 10 years ago I got a quote of many $1000s for a survey since the nearest section corners that had been located were a few miles away. The cost was so high since the crew would have to clear line-of-sight from those known corners to my land.

I said 'no thanks'.

Some years later I was getting ready to sell part of our land and I asked the same survey outfit for a new quote. The new quote was $1000s less (although still spendy) because the surveyor had invested in survey-grade GPS gear. Translation: They did not have to clear line-of-sight a couple miles into the bush.

Moral of the story: When you are in this situation, make sure the surveyors bidding on the work have GPS-grade survey gear. They do not all have that stuff yet.

Finally, since you asked the question I hope it is OK for me to mention that I am a software developer working on this very issue. Here's my homepage:

Joseph, the Gmap4 guy

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