I will just add that it is also common in my area, both past and present, just to assume a line as being north. With GPS, its less common but still done. The way I look at it the bearings are there to give the angles at the corners.
What about this scenario?
The basis was stated as "North", but what if the north to which the Surveyor of Record referred was "North" from the last deed of record, which was 70 years ago (I know, this is just a guess)? Would the declination from 1940 (or whenever) differ by an additional 30 minutes? How far back would one have to go to see a similar declination?
AS usual, fun topic and nice pictures. Did the Oregonian surveyor have a good time? Did you show him some of the local flora and fauna, perhaps some from even further south, like processed fluids from the agave family?
A perfect Bearing is of little use unless you know the end points, One end might work if you have lots of confidence in the grid system and know that the bearing you are retracing and those on around the tract have been properly determined along with the coordinates you are using as a starting point but there are no checks until local evidence is discovered or recovered showing that you both did well or that one made an error. Without further work you have no way to determine who made the bust and you end up using local evidence anyway. Monuments and Survey records are still King.
jud
:good:
I thought this horse had already died a long time ago
Why are we still beating the poor thing?
There are two schools of thought. They will never agree to become a single school of thought.
I'm right and your're wrong. End of discussion.
> A perfect Bearing is of little use unless you know the end points,
The real value of knowing the actual bearings of lines with very low uncertainties with respect to some independently reproducible North is that you can much more easily identify the monuments that have been shifted out of position. Otherwise, if you're left to somehow derive that "North" only from such monuments as remain after the passage of time, you're often dealing with monuments that have been shifted out of position by fence builders or other causes. Knowing the correct orientation of the parcel boundaries is a big help in ciphering that all out.
What about this scenario?
> The basis was stated as "North", but what if the north to which the Surveyor of Record referred was "North" from the last deed of record, which was 70 years ago (I know, this is just a guess)?
It's entirely possible, and even probable, that the "North" to which the bearings of the lines of that lot refer was from some boundary survey made decades ago. It would be possible to find out. The large error in bearings would be preserved by the RTK methods that have been widely used, i.e. "calibrate" on a couple of boundary markers using some pre-cooked coordinates and go from there. The fact that the front and back lines are so far out of relative position, but nearly exactly parallel, suggests that the control for both may have been put in on different days using different "calibrations". I'm not sure and can't say that I really care enough to do the autopsy.
> Did the Oregonian surveyor have a good time? Did you show him some of the local flora and fauna, perhaps some from even further south, like processed fluids from the agave family?
We saw a whole bunch of non-Oregon-type plants: mesquite, palo verde, live oak, hackberries, cat claw acacia, and a good amount of prickly pear. Birds included wild turkey, road runners, scissor-tailed flycatcher, red tailed hawk. No feral hogs. No coyotes.
>
> Perhaps the surveyor for the subdivision used NORTH for one side of the parent tract and everything else fell however it fell. His NORTH being whatever it really was by some definition between those to monuments.
geez, that is gold star Assumptions there.
Really, is that land surveying?
Some PLS arbitrarily defines North by spitting in the wind or observing moss on some tree.
This is a relatively recent s/d. I would think that the local agency review of the final s/d plat would have some questions and corrections pertaining to this methodology.
The corn screwed bearings on the lot may not be a big deal for now but if they were translated to the s/d boundary than one should see the red flag for future work.
> This is a relatively recent s/d. I would think that the local agency review of the final s/d plat would have some questions and corrections pertaining to this methodology.
Yeah, I'm pretty sure that the county would have required a digital submission of the plat with state plane coordinates on various corners. That's another part of what makes the wacky bearing basis so odd.
> I didn't take it that the monuments were staked incorrectly - just that Kent's calc'ed bearing didn't match the plan bearing, supposedly on the same system.
I was off on a bit of a tangent focusing more on this part of Kent's post:
> So, along the back line the record bearing differs from the true bearing by 2°41'07", the exact same value as for the front line for all practical purposes.
> The side lines? They were essentially parallel and the difference between their record and true bearings was 2°42'57". So the lot was racked out of square by about two minutes,...
The point I was discussing was, that even if the basis of bearings was off or wrong, it seems to me that the relative bearings of the original surveyor should be to a better order of precision. (ie: if you turned the angle from the front line to the side line the angle should match the difference in bearings by much closer than 2 minutes.)
I agree that the original monuments are where they are, but I don't like the fact that the original survey wasn't even close unto itself. Hence the assumption that RTK was probably mixed in. If they had actually twisted angles, that relative difference would be much closer.
Are you saying that if you don't match the endpoint of a line based upon a retraceable bearing then that endpoint is suspect and has probably been moved? Do you then decide to set another monument based upon matching the record bearing assuming that is where it should have been to make things 'work out'?
Honestly, that concept is completely foreign to me and going between solid record monuments is the only and number one concern (unless the monuments are missing) and the bearings between the bona fide monuments then just become what they are. Prior to GPS there were a whole lot of surveyors who could not accurately record true bearings. There is another large group of surveyors now screwing it up with GPS.
Bearing Basis for Profit
But if that plat gives the bearing for the southerly line as S 89 30 W and I set up with that as my reference, how is that any different? What if they left off the basis statement entirely? You can still pick a line's bearing (any line) and turn angles to look for other monuments. I contend that an assumed basis of bearing statement is worthless.
I think the real question is:
Does the previous survey meet state standards?
If it does, then it's no one's business but the client who paid for the survey.
This dead horse is almost..
..as good as the "ice water" dead horse a week or so ago.
Bearing Basis for Profit
> I contend that an assumed basis of bearing statement is worthless.
Well...perhaps so. I do think it is good for the surveyor to state a basis of bearing, however, regardless. the client or a retracing surveyor will know the value or to what level they should be able to rely on the bearing. (If a bearing is "assumed" they know that the only way they can get on the same bearing base is by finding two original points that the survey is calling for, and hopefully know which two they found).
If the surveyor doesn't say that it is "assumed", for one the client doesn't know. Even more so, the legal implication would (or might) be that the bearing between two points is "true" to the precision annotated. If I annotate that the line is "west", that is one thing, but if I annotate that the line is N 88° 33' 13" W, that has all kinds of implications including some kind of precise bearing base if not stated otherwise.
Bearing Basis for Profit
> Canlong as ebodand xplain to me how "east line of parcel is assumed northThey lls me anythingcadastrre's special about that line? It looks to me like it's equivalent to "user can pick any line on the plat and use its bearing for computation."
>
> Is there something about error propagation I'm missing? I doubt it, since the basis of bearing statement gets used most often on transit/total station jobs where what is actually measured is angles.
Historically, it can generally be said that the bearing of a line relative to the stated basis of bearing represented the angle of that line relative to the basis. It was not really intended to be be a statement about that line's angle relative to true north.
This is the case in the original subdivision as well. The stated bearings are more or less correct.
Now, Kent and Gavin find themselves strangely on the same side, as long as Gavin lets the pokes at RTK go. (Which Kent can't help.)
They want a better cadastre. And, while they are right, neither of them works in an arena that makes them appreciate clients that care about $50 on the cost of a bid. That is the real argument: people are concerned that they will have to eat the cost and won't be able to pass it on.
Bearing Basis for Profit
> Historically, it can generally be said that the bearing of a line relative to the stated basis of bearing represented the angle of that line relative to the basis. It was not really intended to be be a statement about that line's angle relative to true north.
That flies in the face of historical and present day usage. The typical source or basis of bearings is one of the following:
(a) true North (or geodetic North),
(b) grid North of some stated projection,
(c) the "North" direction to which some stated bearing of a particular monumented line refers, and
(d) magnetic North less some stated angle of variation.
Obviously, the bearing of a line that uses a monumented line described as running N30-04-15W as its bearing basis refers to the "North" direction that is 30-04-15 clockwise from the direction of the monumented line. So in all cases "bearing basis" amounts to answering the question: "Which way is what you called 'North' when you reckoned the bearings you gave?"
> This is the case in the original subdivision as well. The stated bearings are more or less correct.
By any familiar standard, they were less correct. :>
Bearing Basis for Profit
Ok, I'll agree that a statement that "bearing basis is assumed" is worthwhile to keep people from looking for a deeper significance. The detail of picking one line's bearing is what is worthless.
> Are you saying that if you don't match the endpoint of a line based upon a retraceable bearing then that endpoint is suspect and has probably been moved?
I'm saying that one of the best clues available to a surveyor to be used in determining which monuments remain in the same position and which have been disturbed are accurate survey measurements that represent the relative positions of the monuments at some earlier date. Accurate distance measurements are one part of that and accurate determinations of the directions of lines are another, with accurate directions on an independently reproducible bearing basis being more useful than those not.
> Do you then decide to set another monument based upon matching the record bearing assuming that is where it should have been to make things 'work out'?
You mean, when a monument has been disturbed, does it still mark the original corner? The question pretty much answers itself, doesn't it?
> Honestly, that concept is completely foreign to me and going between solid record monuments is the only and number one concern (unless the monuments are missing) and the bearings between the bona fide monuments then just become what they are.
Well, as a rule, you will very seldom find entire subdivisions marked with monuments at every lot corner that would be impossible for a fence builder to relocate or for construction activity to shift. The real world problem is how to maintain boundaries in the same position since real world boundary monuments are usually not "solid".
Bearing Basis for Profit
> Ok, I'll agree that a statement that "bearing basis is assumed" is worthwhile to keep people from looking for a deeper significance. The detail of picking one line's bearing is what is worthless.
It could be irrelevant, to some. But, I can assure you it is not worthless when I attempt to follow the platting surveyor's footsteps.
