Need Surveying Advice

[bobkrack]

Bob: Like Zeuspaul said, there are many definitions for North. You would need to know which was used on your property description. The bearings shown on your deed are mainly used to define the angular relationship between two legs of a figure. Since you have the NW and SE corners located, your best bet is to apply your declination ( whithin a degree should work in your case ) to compass and try to "strap" in your other two corners. Measure the distance with a 100' chain from NWC toward NEC and mark the
Bruce

The legal description is "parcel number 11 of subdivision 27 beginning at a point etc." with the description of the subdivision. In other words, the entire subdivision is described but the individual parcel is described only by a map (giving distances and angles) of the entire subdivision. That map shows the north arrow.

Had I the tools and exact knowledge to find any of the corners by actual surveying, I would have never have asked my question.

I do have two surveyed corners, my question is really about "solar noon".

I have calibrated my compass to astronomic north by sighting on Polaris, as near as my eyes will allow and it shows very close to "solar noon" by the solar noon tables on the USGS or AOOR site. At this time of year it is around 1:45PM in my locale.

I plumbed a 10 foot pole at the SEC and another 20 foot away in the shadow of the first at local "solar noon" and extended that line the correct distance, believing my distance to be within a couple of feet of the actual property line length but perhaps off by twenty or thirty feet east or west.

I triangulated perpendicular to "solar noon" from the NWC and measured out the correct length but am not quite so certain of my results because of brush on the line.

My only need for this corner is for brush clearing as mandated by the California Department of Forestry (Fire) clear distances from dwellings. My neighbor to the north will work with me without regard for the absolute concern for "my side, your side" arguments. The property to the east is vacant so I guess it doesn't make too much difference if I clear a few feet over the line. Of course, it will not make too much difference to CDF whether the clearing area (with respect to the actual line) is accurate to the inch.

Absolutely accurate or not, is my procedure likely to be fairly close to the NEC?

In proof-reading this post, it looks a little antagonistic but that is certainly not my intent.

Thanks,
Bob

 

[HomeBrew2]

...

Maybe this will add a bit to Bruce's good commentary. There is usualluy no requirement, at least in Kalifornia, that bearings shown on a map on in a deed be based on any mandated "north", astrononical, or otherwise. Typically, a map will reference a "basis of bearings", most often, in my experience, that reference is to a previously recorded map. The previous map may have referenced another map, and so on. None of which may have any relation to any of the assorted "norths" that Bruce mentioned. As he stated, bearings should really just be thought of as another, and neater, way of denoting the angular relationship of the lines.
I'm curious if your triangulation perpendicular to solar noon indicates that you happen to have lines that are shown exactly prependicular on your map, or are you trying to setup a cartesian coordinate system on the ground?
If you could provide a scan of your map, we might be able to help better.

 

[zeuspaul]

Bob, your procedure is the one recommended by Bruce except you should use the corner developed from the distances as Bruce recommended. Use the direction from your compass and the distance from the *first try* from the SE and NW corners. Then correct the direction you went based on where the first tries ended up and measure the distances again.

Make sure you are using horizontal distances. If your land is nearly level you are ok. If it is sloped hold one end of the tape higher than the other to approximate a level measuring distance. Use a plumb bob or drop a rock at the end of the tape that is off the ground to mark a *measuring point*

Solar noon will not do you any good except as a *first try* direction as you don't know the basis for your north as already indicated.

Measuring two distances should get you as close as your distance measuring skills will allow. The parcel is somewhat rectangular. If it were another shape distance may not be a good procedure.

zeuspaul

 

[bobkrack]

Bob, your procedure is the one recommended by Bruce except you should use the corner developed from the distances as Bruce recommended. Use the direction from your compass and the distance from the *first try* from the SE and NW corners. Then correct the direction you went based on where the first tries ended up and measure the distances again.

Make sure you are using horizontal distances. If your land is nearly level you are ok. If it is sloped hold one end of the tape higher than the other to approximate a level measuring distance. Use a plumb bob or drop a rock at the end of the tape that is off the ground to mark a *measuring point*

Solar noon will not do you any good except as a *first try* direction as you don't know the basis for your north as already indicated.

Measuring two distances should get you as close as your distance measuring skills will allow. The parcel is somewhat rectangular. If it were another shape distance may not be a good procedure.
zeuspaul

zeuspaul,
By "first try" I assume you mean at the first shadow demarcation at solar noon? I set the first pole in the morning and set the second exactly in the shadow of the first one at precisely solar noon.
If you mean my first measurement of line length, I think I know what you mean - the point I developed on my first NS/EW measurements?
The parcel is nearly as rectangular as can be.

HomeBrew2,
The land is essentialy level, lots of brush. I will try to scan a piece of the map big enough to show the subdivision and still show the parcel.
Yes, Bruce's posts are extraordinarily enlightening!
The only thing I am trying to set out on the ground is the NE corner.

Thanks all,
Bob

 

[BruceR]

Shaley,
My bad, (N-2) is it. By my definition a triangle would have 0 degrees. My proof reading is not so good at this time of morning. Nice looking software. I use Simplicity Systems Site Survey. Any chance of least squares ? I overlay my deed sketchs on the sat photos that are done in shades of red rather than in color because I feel they give better definition. Are you familiar with those ? I think they are USDA based and date from 2004.

dmccarty:
I should have noted that marks vary by region. I mark my hubs with a small blaze and a hack with a piece of flagging in the hack. I have seen remains of flagging in trees that I marked twenty years ago.

Bruce

 

[BruceR]

The legal description is "parcel number 11 of subdivision 27 beginning at a point etc." with the description of the subdivision. In other words, the entire subdivision is described but the individual parcel is described only by a map (giving distances and angles) of the entire subdivision. That map shows the north arrow.

Absolutely accurate or not, is my procedure likely to be fairly close to the NEC?

In proof-reading this post, it looks a little antagonistic but that is certainly not my intent.

Thanks,
Bob

Bob:
I'm sorry, but solar noon is beyond my area of expertise and if it would allow you to calculate astronomical North, it would only do you any good if your plat was based on True Bearings. If you know of two corresponding monuments in your subdivison with line of sight between them, simply take a compass reading between them and then by matching your reading to the plat you can figure your rotation, or declination. By matching the local declination in this manner you can override any effect of the minerals in your area. I practice in a very iron ore rich area and it works for me. Because of the brush, expect your measurements to be short.

When I speak of doing a solar observation, I have an total station set up on one of my hubs and am back-sighting another hub. Through the use of a solar filter, I take three readings on the location of the sun direct and three readings with the scope reversed. I can calculate the True bearing of my hubline at this point and rotate everything to match.

HomeBrew2 is has good advice about basis of bearing. It's unknown in most cases. The really old surveys ( 1800's ) hereabouts give the declination used and from that you can calculate today's declination. What I have found by doing solar observations is that the old surveys run within 15 minutes of True, while more recent ( 1940-current ) surveys in my area are anywhere from 1-6 degrees off.

I think what zeuspaul means by "first try" is that it will probably take a couple of turns before the two distances intersect. I have been doing this so long that I usually just pace the distance if under 500 feet and allow an extra step ( or more ) per hundred feet if brushy. I don't start cutting brush until I have found the monuments. Tie two pieces of flagging on the line you want to hold and have the head chainman work backwards and use them to line up on, tying more as he goes ahead. My neck of the woods is full of brush, briars and cut-over timber and its not uncommon for me to have to tie a piece every 25-30 feet. We have a lot of tracts here that border reservoirs which are monumented along an imaginary zig-zag contour line every 200-500 feet and by using this method I can generally wind up within a 5' radius of the corner on first try, then use the metal locator. If I drag the chain with me I can usually be a foot or less but that requires the use of an extra man.

I have two big old brass Gurley surveying compass' that I use sometimes on the larger retracements, but for everyday use I prefer the Suunto KB14 360R in Azimuths rather than Bearings. It will generally keep me within 15 minutes and that is well within needs for most cases.

No offense taken, I realise that without tone of voice and body language things are not always as they may seem. I need to constantly check myself as I have a sarcastic wit which is not appreciated by many.

Bruce

 

[zeuspaul]

Quoted ***If you mean my first measurement of line length, I think I know what you mean - the point I developed on my first NS/EW measurements?
The parcel is nearly as rectangular as can be.***

That's what I was refering to. There is no need to refine your solar observation. The North arrow on your map says North...It does not say Solar North. Solar North has nothing to do with the direction of your property lines. It is only useful in establishing a general direction of your property lines.

You are doing a distance distance intersection.

Zeuspaul

 

[bobkrack]

Bob:
I'm sorry, but solar noon is beyond my area of expertise and if it would allow you to calculate astronomical North, it would only do you any good if your plat
Bruce

Bruce,
Thank you very much. Solar noon is "mid-day" in the daily solar cycle - "High Noon" in the old west as it were.

NOAA Improved Sunrise/Sunset Calculation is the online calculator, it has several large cities but you must input lat/long if you want precise local time.

Thanks again,
Bob

 

[TNhobbyfarmer]

Well hello again guys. I haven't been on TBN for a few days now. Unfortunately, I had to endure prostrate surgery Monday. I feel well now but haven't felt like going upstairs to the computer until now. I don't think I will be able to trudge through the woods to look for those corners for a few weeks.

Anyway, I am glad that my post started a nice long thread. I have learned a lot by just reading you guys. It just has reinforced the fact that I'm a mere kindergartner when it comes to surveying. You guys have definitely got it going on with respect to knowledge of the subject. Some PHD's in my book.

I will revisit the post when I have some/any progress. Thanks again for all the input.

 

[BruceR]

Glad to see you are up and about again.

Bruce