How To Explain Basis Of Bearings To Non-Surveyors?

Pictures

Many people need to see something rather than hear something before they understand. Not just surveying stuff, everything.

Assumed North would be the easiest. Have them point to something they think is directly North of them. Then you pick a different something a short distance away and declare that, in your opinion, that way is North. Then point out that the angle between the two lines is some number of degrees such that what they would call zero degrees from north is now X number of degrees in your system.

Maybe a down-to-earth scenario would help. Some lots have granite monuments placed back when the meadow is sold off by the retiring farmer. Fifty years later trees and brush have grown up so much that only one monument can be found. Nearest recorded monument is 500 feet away. Which direction do you go to look for the other? Uncertainty in the direction directly affects how much you have to clear brush and dig for the other monuments.

I generally state that the reference to north is a general reference and that the bearings are a means of expressing the angle formed by the two lines. Plat could be prepared without bearings and only angles.

You can't, it's hopeless.

Never mind Non-Surveyors, I would be happy

If I could explain it to some professionals I have dealt with.

"More or less to" is another good one.

I'd probably use a blank sheet of paper. Ask the individual to orient it to what they think is north. There you have 'assumed' north. Place a compass on the paper and orient it to the needle. 'Magnetic' north. Apply the declination. True north. If they don't have a blank and glazed look on their face at this point. World is round, right? Ask them to place that flat sheet of paper over a basket ball or whatever round object and ask them to try and wrap it smoothly around the ball without creating a fold or a crease. Can't do it. Make a cone from the paper and slip it over the ball. Voila, you have a basic conic projection. Now which way is north? 😉

Most people are visual thinkers. If they can see it, they can understand it.

^^^^This

simple-basis of angle measurement

The basis of bearing is just a basis for angular measurement.

Explaining math or surveying measurement to the layman is a hard task.
The general public dread such explanations based on their math knowledge. (See C. Billingsley’s recent post).
The best alternative is to use an analogy of some kind.

Most people listen to music, so explain how a band has to be on the same page so to speak to play music.
If an orchestra is playing from some transcripted music, then the sheet music has to be notated in the same key. If one of the orchestra sections have a different “key” notated, they will be out of harmony of the others.
Most people eat.
So if you are cooking a gumbo and the recipe calls for 2 cups peppers, one must be certain that everyone uses the same peppers. There is a difference between 2 cups of bell peppers and two cups of habanero peppers.
Sports are usually the common layman analogy. Basketball is in the forefront now.
Explain to play the game correctly, the ball has to be standard to the sport. You can’t have a football, tennis ball, baseball to play basketball.

substitute bearings for key, peppers and ball

That's just great. Now I'm craving Cajun food.

>
> I can understand that what seems simple to me is difficult for the non-surveyor. If anybody has a way to explain this to others by using simple words and examples, please pass it on. Any help here is greatly appreciated.

Search this topic on this board. There is a vocal minority of PLS's that can't seem to get it either.

simple-basis of angle measurement

> The basis of bearing is just a basis for angular measurement.

Try using that for an explanation to the general public. In fact, use that explanation for the woman I had trotting through the woods with me who was emphatic we were on the wrong line. She of course was holding her plastic, Coleman compass and orienteering to North, just as it stated on the '79 plat.

Keep a USGS topo map in your truck that has the three arrows at the bottom. One with a star, one with GN for grid north, and one with MN for magnetic north. Then explain that different surveyors have used different norths over the years to measure an angle from. If they understand that, then explain that magnetic north varies over the years and some surveyors match the bearings on the old survey so they would be different than any of the other three.

Then you can tell them to pretend the star is a football, the grid north is a basketball, and the magnetic north is gumbo with too many habanero peppers.:-D

James

This is why this board is so great. Thanks for all the answers. Now I'm hungry too.

Do I put the baseballs or footballs in the gumbo?

Dale Yawn,
Savannah, Ga.

It's a surveyors thing, you wouldn't understand.

> I need to find a simple and clear way to explain the basis of plat bearings to non-surveyors. Most people assume that all bearings are the same, that you just run a line in that direction, and that's that. When I try to tell them that not all bearings are referenced to the same kind of North, then I get a lot of blank stares. "North is North" isn't it? I then start to tell people that there are different flavors of North, such as Magnetic North, Astronomic North, Grid North, Assumed North, etc. It doesn't click with them when I tell them that you can't mix bearings from one flavor of North with another flavor of North. It really gets complicated for them when I start to tell them about rotating one bearing base to match another so the bearings are on the same base. They don't quite grasp the concept that two plats may exactly describe the same property size and shape, but that the orientation and bearing values may be different.

"Well, in effect, they had their compasses adjusted differently. Some of them knew exactly which way North was and some of them assumed that some earlier surveyor had determined which way North was and adjusted their work to match that earlier surveyor, but without really checking whether the earlier surveyor had correctly determined North in the first place."

"Even though the bearings that different surveyors reported are different, from my work I determined that on the ground the lines are the same."

Northern Opinions

First, it is probably a good idea to tell non-surveyors that north is an opinion and not an absolute fact. North is NOT north. One's opinion of north is not another's. It is then easier to explain that angles are referenced to differing opinions of north. The rotations done are the surveyor's mathematical magic that brings all opinions together.

That's a fact, not an opinion!

Northern Opinions

No, you are wrong.

North is the direction to the candy cane or barber pole sticking out of the ice at the north pole.

Just a commentary...

I have noticed that sometimes old timers, sitting on the intersection, would look down a line of rebars, pins, and/or pipes on Line A then look down a line of rebars, pins, and/or pipes on Line B.

The map produced by the office (say before 1980 or so) the bearing of Line A would come from one source and the bearing of Line B from another (or maybe the same source) but when you go set up on the intersection today and turn the angle from Line A to Line B the angle is significantly different from that computed from the old Survey map (several minutes or sometimes, worse, several degrees). Enough different that it wasn't because it was too small for their transit to detect.

I've seen this enough to think back then the office had little connection with the field or the office just prettied up, cooked up a map from whatever sources they felt like to make it all look good.