Estimating Acreage

[Darin]

Hello all, first time poster long time listener. Mainly because I never had anything to add or any questions to ask, but thats about to change in the near future.

Does anyone have a fairly accurate method of determining acreage without a survey.

GPS maybe?

This will be about 100 acres of fairly hilly terrain.
Thanks
Darin

[Rocky_J]

How about legal records? Or can you look it up on MapQuest or some other map and scale it out?

Where would one find hilly terrain in South Florida?  

[beenthere]

Welcome into the "Forum".
Aerial photo's would be my suggestion. Various agencies have them, and there are also ways to get them on the internet (for some areas).

Maybe some of the FL guys will know how. Then you can do some measuring and come pretty close (but need to know how accurate is "fairly"   )

[Bro. Noble]

As Rocky says,  you can get a fairly good estimate from an aerial map if you know the scale and the plot is rectangular.  Deeds and tax records can sometimes be way off.

If your plot is irregular,  you can go to a USDA field office and ask them to use their aerial photo and a plinimeter.  They can come real close.

[Ron Wenrich]

I use a dot grid, which you can buy for a few bucks from someone like Ben Meadows or Forestry Suppliers.  They were designed to fit over a photo, but I've used them for any type of map that I have made.  It really helps when I plot out an area for a management plan or when I'm doing any type of inventory work.

There are 64 dots per sq in.  Count up how many dots there are in your area, and multiply by the acreage represented by each dot.  

For example, if your map scale is 1"=660', then each dot represents 0.156 acres.

Low tech and cheap.  Who could ask for anything more?

[SwampDonkey]

Ron's and beenthere's suggestion of using aerial photography and a dot grid is widely used by forest resource folks around the globe and if you ground truth your aerial photography in the vascinity of your tract of land you will be very close. Since your in Florida there isn't going to be much variation in scale on your photo. Some forest resource photos have a scale marked at the bottom and a mapsheet number as well. That scale is above sea level (ASL), not height above ground. I've seen a difference of 1500 to 2000 meters in scale because of terrain and air turbulence when flying, based on scale=12,500 meters. You can make your own dot grids with an Inkjet printer and Inkjet transparency with a drawing program like Adobe Illustrator (PC/Mac) or Power Draw for Mac and any CAD or DTP software. I have a dot grid of 1 point per ha, but often use 1 point per 0.25 ha for small parcels. If dots land on the perimeter boundary than I count every other one. Just place the dot grid at random on the photo over your coverage area and average 3 tallies in this way.



Some typical photo marks on forest resource aerial photos.

Ok, so what's ground truthing? Simple stuff. Just get out your measure tape and measure the distance on the ground between a couple of identifiable land marks which you can distinguish on your aerial photo. On the ground there may be two line fences, for example which correspond to the same line fences on your photo. With your measure tape you've determined the distance between the two edges is 2500 feet and on your photo this distance is measured as 1.5 inches or 0.125 decimal feet (ie. 1.5/12). With simple ratio 2500 feet/0.125 feet = 20000  or the scale is 1: 20,000. This will be quite unneccessary for you folks in Florida since your height ASL isn't significant enough to influence the scale like it would in the Appalachians for instance.

You may be able to contact your regional forestry office to look at a map of your area with the flight lines marked on it. Typically up and down the left hand side are the flight line numbers with photo centres  marked with an O, and every 5th photo labeled, like such.

DNR00503            5              10             15
---------------------------O---------------O--------------O-------

cheers

[Jonas]

GPS is great when teamed up with Maptech's "Terrain Navigator".  You don't even need the GPS part but GPS will work in that application and is really great.  You can sit at your computer and with the distance tools, draw a line around the area for which you want the acreage and it will tell you exactly how many acres along with other information like elevation.  
I tried another Mapping application and dumped it and went to Maptech, who's computer images are (in my opinion) as good and a lot more handy than the Geological Survey's paper maps from which I guess they are taken.  
The acreage thing is especially useful to do a quick check on USABLE  land up for agricultural lease.  (Not always the same as deed acreage.)  For forestry use, it should be very useful since depending on the last update of the topographic map, the wooded areas are visible to a pretty accurate degree.  
Maptech topographic maps are not especially cheap, but well worth it.  Since getting them, I have never purchased another paper topographic map.
My acreage checks are usually within an acre or two at most for 100+ acre fields.  And that's usually because the trees grow into the fields over  time if not cut back by the owner.  Farmers don't like to pay lease for land they can't til.

[Minnesota_boy]

If you are after a reasonably accurate acreage for a piece of property for which you know the boundary and can traverse it while holding a GPS, the GPS can give you the acreage.  For example, I have a field that has been measured and each plot within that field has been labeled on a map.  However, I have changed the boundaries of the plots within that larger field and would like to know the current acreage of each plot, so I took my GPS and walked the boundary of each plot and the GPS will tell me how much acreage was enclosed by my walk.  I have to reset it for each plot, though.

[Darin]

DanG it guys who said anything about it being in Florida. I'm in a hurry to get out of here. The property will be in N.E. Kentucky when I ever find it.

(Rocky J) Quess you never  been in S. Fl. before, of course we have hills here. Why they are fire breathing, in the clouds monstrositys. Behemoth masses of land, towering in the sky.

We call them "dumps"

As far as the legal description goes that comes from the deed that is about worthless. They read more like somthing that the Indians would describe from the 1750's. In fact thats were I believe they got some of the descriptions from in this area.

Thanks everyone I will get busy on some of these methods and see what works the best for me.

Darin

[SwampDonkey]

The GPS method would be great if you know the boundaries are well marked. I wouldn't buy a GPS for a one time measurement though. But if you have multiple uses they are a nice piece of hardware. Garmin's Map76 or 76s is a nice unit as you can measure a tract to get area. You have the clear the log and start a fresh tract for each measurement, and you can save up to 8 tracks. I don't think they include software other than maps to download into the unit. There are already maps built into its onboard ROM for places and names and some roads. I don't think Megellan will show you a map and area, unless you get the Thales Mobile Mapper with its GIS office software. From what I gather in your posts, I'de try the aerial photo methods first. As Ron says its low tech and cheap. Its definately not rocket science and no trying to figure out buttons and software.

[redpowerd]

it may not work for a chunk of woods , but a local farm service agency (FSA) office should be able to print you out an areal map with defined boundries and acreage. you can also get a soil map while your there. i get maps whenever i do custom feild work.

[Tobacco Plug]

As far as the legal description goes that comes from the deed that is about worthless. They read more like somthing that the Indians would describe from the 1750's. In fact thats were I believe they got some of the descriptions from in this area.


Darin

If you don't know where the boundary markers for your property are, and you are planning on buying this property, you should have the land surveyed.  I would further suggest that you pay the surveyor the extra charge to have the boundary lines chopped so that you can come in and mark them with paint.  They surveyor will locate all corners and if markers are missing, he will set new ones.  

Some of those old metes and bounds descriptions are pretty confusing- "from the white oak at Wilson's southeast corner proceed North 17 degrees 27 minutes west  27 chains 3 links to a creek, thence North 40 degrees 40 minutes east 100 chains 8 links to a pile of rocks with an iron rod set, this marked with ash pointers..."  

Someone told me that in Scotland the laird would take his oldest son to each corner of his property (which the son would one day inherit) and give him a thorough whipping so that he would remember where the corners were.  I am luck my father was not as rough.  He would just say that we were going hunting and then spend the afternoon walking the boundary lines of the property while carrying shotguns.  We never did shoot much game, and it wasn't until I was about grown that I realized that I had been tricked!


Good luck with your escape from south Florida.

[SwampDonkey]

Excuse my abrasive attitude, but I don't think that a seller should be able to list a property that isn't properlly marked out. There are some land owners doing about the same thing up here with stumpage. They think the contractor is going to pay for a land survey and that's when someone mistakenly cuts over the line because he just gets out the roll of ribbon from behind the seat. Its the owner's responsibility to have his lines surveyed, not the stumpage contractor's. Why not factor the cost into the purchase price, problem solved. So far there is no requirements for this, as far as I know. Realestate won't even have it surveyed either. I wish the pencil pushers who fix that loop-hole.

As redpowered suggests, maybe an agri centre has it mapped or marked on current aerial photography if its part of  a soil conservation or agribusiness program of some type. Its likely its not, unless your going to take up farming. I say this because alot of those types of programs are long term with penalties against turning the land over to other uses.

[Tobacco Plug]

Excuse my abrasive attitude, but I don't think that a seller should be able to list a property that isn't properlly marked out.

Swamp Donkey,
I don't think your attitude is abrasive.  But, Darin is planning to buy the property.  It has been a while since I studied any real estate law, but I believe that the buyer is the one responsible for knowing what he is purchasing.

If I sold a piece of land, I am selling what I say it is, as stated in the deed's description.  Once the sale has been made, it would not be fair for the buyer to come back to me and say that he didn't get what he thought he was.  I don't think that it is a question of honesty either.  After all, I have owned the land and have used it based on my knowledge of its boundaries.  If a surveyor comes along and determines that the previous description is wrong, that is not necessarily because the seller is dishonest.  

It is the buyer's duty to know what is his.  Best way to do that is to survey the land.  I am sure that a bank would require a land survey to finance the purchase, too.  

[SwampDonkey]

I was suggesting before the sale, the owner should be responsible enough to have the survey done. Evidence marked out on the line , in my opinion, would be better. A piece of paper describing markers like old trees that have died and disintegrated isn't much use. A more modern deed with measurements and bearings excluding parishable monuments would be much better, of course. I've also seen people calling fields a certain acreage, then measure it and find 10 acres difference. I know I'de never sell land without line evidence and when I see land being offered for sale something in the back of my mind makes me suspicious when its not marked out. Sorry, that's just me I guess.

[Ron Wenrich]

I found a tract one time that was supposed to be 150 acres.  Mapped it out and did a plot cruise to find that it was off by 50 acres.

I use my dot grid on maps more than I do on photos.  I can get fairly good accuracy from ground estimations during a plot cruise that can help put different timber types into seperate compartments.  Makes for a pretty good inventory.

[SwampDonkey]

Yup Ron I agree. Timber typing your cruise makes for a much better estimation of volume. That's what I do also and having up to date photography helps tremendously also. I've seen some people's work where they grouped a whole 100 acres as one stand and their cruise over estimated the volume by 30%. I was told this by a woodsman that hired the cruise done, and bought the land lump sum. He cut the wood, and the volume just wasn't there. Another thing to, and trust me on this one. Never do a sample on stand boundaries, especially if the stands are under 10 acres.  I recall a stand of swampy-like cedar which was short and stunted. The stand had hemlock around its perimeter and big cedar because it was higher and better drained ground. A couple of plots landed on the stand boundary and one in the middle of it. The cruise returned more volume of hemlock than cedar, which was not the case at all. It also indicated the average diameter was bigger than was the case. I make a practice to offset by 25 meters away from edges.

[Tobacco Plug]

S.D.
I guess we have kind of been talking about apples and oranges.  I fully agree that an aerial photo and a dot grid or planimeter will give a pretty accurate measure of a tract.  So, to Darin I suggest that he go to his local Farm Service Agency and see if they have some aerial photos of the property.  We are lucky here in NC since there were so many tobacco fields that most of the land (at least in this part of the state) has been photographed.  Also, many counties have mapped their land from tax records and this can provide a useful tool.  Finally, I am 100% with you that landowners who offer timber for sale who haven't maintained their property boundaries and can't find their corners should have the land surveyed before selling the timber.  Unfortunately, the law is on the other side on this issue.  Nonetheless, it still would be the honest thing to do and would avoid a lot of problems down the road.

[SwampDonkey]

Ron about the acreage on forest land again....I did a management plan for a guy once and he told me what the acreage should be handy to and I looked up the property in records and they listed it as being 250 acres more then it actually was. The number of hectares that got entered in the database by the government was 349 ha and it was suppose to be 249 ha. I kept recalculating the acres a few times and never did find that other 100 hectares. To top that off the government agency responsible for records has a non accountability clause.

[Ron Wenrich]

But, look at all the extra tax money they get.