Finding survey pins

[Pat]

In case Egon hasn't sufficiently confused you... let me take a hack at it.

Can dead men vote twice?

Can - - - - -(C) Compass
Dead - - - - (D) Deviation
Men - - - - -(M) Magnetic
Vote - - - - (V) Variation
Twice - - - -(T) True

There is true north which varies little and can be assumed constant for your purposes. The compass does not give true north. The compass, strictly speaking, does not give magnetic north either.

The mathematical difference between true north and magnetic north is called Variation and variation can and often does vary from location to location. At any given location variation is typically sufficiently constant to be assumed so.

There is also a difference between magnetic headings and compass readings which is called deviation. Deviation may be negligible with your compass use, especially if little or no ferromagnetic substances or electric currents are close to the compass. Try to read your compass while it is NOT NEAR iron, steel, nickle, electric devices, magnets, etc.

A good hand held GPS will typically get you to within several feet (low double digits) of a specific point. Depending on the features of your GPS it may or may not give you a readout of distance and bearing to a reference point or otherwise be useful for your task.

Surveyors use GPS units with temporarily stationed fixed location auxiliary equipment and can get accuracies to within a fraction of an inch. No commercial off the shelf consumer grade units will get even close to that. The best most GPS can do is to deliver good repeatability, i.e. bring you back really close to the same point once that point has been registered by the unit. Absolute accuracy is less. The ability to take you to a specific spot via lat and lon is less accurate than the ability to return you to a spot.

An engineer's compass (style of instrument) is the minimum instrument to use to try to follow metes and bounds. That in concert with a good 300 ft tape should git 'er done if your sight lines are not obscured in heavy brush, timber, or by topography.

Pat

[egon]

</font><blockquote><font class="small">In reply to:</font><hr />
So start from that point with a compass and sight
a hair less than 51 degrees north of west.

[/ QUOTE ]

Sorry, that will not work.

With the heading given you have to start from true north and then go the 51??? to the west. [img]/forums/images/icons/grin.gif[/img]

Pooh bear, if the heading had been written as W51 degrees N then you would be correct. [img]/forums/images/icons/grin.gif[/img]

</font><blockquote><font class="small">In reply to:</font><hr />
There is also a difference between magnetic headings and compass readings which is called deviation.

[/ QUOTE ]

This should show up on topographic maps as Declination. [img]/forums/images/icons/grin.gif[/img]

Egon [img]/forums/images/icons/grin.gif[/img]

[Pat]

Right you are Egon. Don't you just hate having to disambiguate overloaded identifiers?

Pat

[egon]

Well how about SSE or WNW all parts of the compass ??? whatchya macallits! [ Rose maybe] [img]/forums/images/icons/grin.gif[/img]

AlBald1:
in your case set the declination for your on your compass. Then figure out your compass heading and using that pace off the distance if looking for an established pin. When near the proper area start looking around. In most cases it will help to have help. Get the helper out ahead and the get them to stand on the line as shown by your compass heading. Then you go stand in their spot and repeat the procedure and on and on. [img]/forums/images/icons/grin.gif[/img]

What's this about swinging a compass Pat?? [img]/forums/images/icons/grin.gif[/img]

Egon [img]/forums/images/icons/grin.gif[/img]

[Pat]

Oh yes!!! Declination is a source of confusion for some of us since the angle the earth's magnetic flux lines make with a horizontal plane normal to the earth's surface "could be" called declination but the topo map's use of the term is to indicate a horizontal variance not a vertical one.

Not to worry though, even though a compass needle suspended such that it can pivot vertically as well as horizontally will still, via its vertical projection, indicate the proper horizontal component of the earth's magnetic field.

Again, I do not like overloaded identifiers that require disambiguation, as often in normal discourse confusion results far easier than recognizing another's use of terminology to be in variance with our own.

Pat

[Pat]

Egon, I can swing it or box it.

Pat

[Pooh_Bear]

Ok, then I got a question about my own survey pins.
Last summer I calculated a heading of 4.94dd S of E.
Should I have used 4.94dd E of S instead?

A neighbor put a fence up and I suspected it was in the wrong place.
But 4.94dd S of E showed it in the right place.
But if it should really be 4.94dd E of S then it is way off.

But it looks right the way it is according to the survey map.
All my angles came out right when I drew it up in AutoCad.
I took the survey map and recalculated it to decimal degrees (dd).
So now I'm real confuzzled.

I just drew it up again in AutoCad using 4.94dd E of S and
there is no way that could be correct.

I'll have to get the original survey map to check my figures.

Pooh Bear



The line from the left comes down the center of a dry ditch.
On the end of that one line is 4.94dd S of E and the other
line is 4.94dd E of S. My neighbor would pitch a fit if I tried
to put a fence up on a heading 4.94 E of S.

Panorama view of my house with aerial views and maps

[egon]

Given a survey heading of say;

N50degreesE

Then the first direction set would be north and the angle would be 50 degrees to the east.

W50degreesS:

First direction would be west then 50 degrees south of west.

Or so I recall the system.

Egon [img]/forums/images/icons/grin.gif[/img]
[img]/forums/images/icons/grin.gif[/img] [img]/forums/images/icons/grin.gif[/img]

[Pat]

Pooh, Very nice presentation. I hope your property is safe from flooding in case Al Gore's Revenge is unleashed up stream of you .

What application software did you use to stitch the pans together? I typically eschew Photoshop and anything at all complicated and just go super simple, IrfanView.

Again, nice presentation.

Around here the surveyors use a metal detector to find buried rods (typically rebar.)

Pat

[Pooh_Bear]

I used MS Paint to put the pictures together.
Yep, if it can't be done with Paint or Irfanview then I don't do it.

My parents house next door has been completely surrounded
by flood water but it stayed just below the wood floor joists.
Flood of 2003
My house is out of the flood plain of the river.

Pooh Bear