DP Tool Club 8/CDASC08.ISO/VRAC/SLY138.ZIP/SIY11.TXT

Text File | 1993-01-10 | 16.9 KB | 304 lines

 SIY11.TXT   Helpful Hints for Surveying in the Real World                  52

                                  Chapter 11

                 Helpful Hints for Surveying in the Real World

In this chapter you will read tales of hard-won experience.  Many of these
inspirations have come while surveying in some deep dark dank muddy hole in the
ground.  This surveying method was devised to give usable data under the worst
of environmental conditions.  Cheaply.  With inexperienced assistants, or no
assistance at all.  The instruments are practically indestructible under
abnormal use.

The only simple way to destroy a Silva Ranger compass is to put it on the
dashboard of your car or truck.  The defroster will cook it.  The plastic
mirror will craze and warp and the compass capsule might get an air bubble in
it.  Silva warns, "Do not lay your compass near [a] radiator[, n]or where [the]
temperature can become excessive, such as on a pavement in the sun." I have
never tried a radiator, but I have defrosted a couple of Rangers.  I don't
spend much time around pavements nor in The Sun, but I never have had any
trouble with sunshine, black rocks, and the Ranger.

I also once broke the hinge on a Silva Ranger by dropping it on a sidewalk.  I
have dropped Rangers on rocks hundreds of times without damage, but the one
time that I dropped one on a sidewalk was fatal.  Stay away from sidewalks!

The basic surveying method is so simple that I have seldom spent more than an
hour teaching someone to survey in a cave.  The worst problem is getting
legible notes.  It takes about ten minutes to master the mysteries of the
compass.

If the compass is tilted, then it will give you the wrong answer.  Be sure that
the needle jiggles when you tap the compass.  Look in the mirror to check
this.  Don't try to look at the compass dial directly.

The best way to improve the quality of your survey is to improve the quality of
your compass readings.  Be sure that you have taken a good compass bearing,
then take another one.  Or better yet, take backsights too.  Best yet, have
your assistant use a different compass to take the backsights.

The compass declination changes with time, as much as a degree per decade.  The
declination map in the Silva instructions is sufficient for most surveying.  If
you have a declination error, it will result in the map being rotated.  This is
more of a nuisance than a calamity.  When you are comparing maps, just rotate
for best fit.  The amount of rotation is the declination error and can be
measured with the protractor.  A new map could be plotted or calculated with
the correct declination if you think it is worth the bother.



 SIY11.TXT   Helpful Hints for Surveying in the Real World                  53

Magnetic declination is shown on the topo map of the area.  The Isogonic Chart
of the United States (see Chapter 14) can also be used to calculate the current
magnetic declination.  Why bother?  The chart in the Silva Ranger Instruction
Manual is a bit dated, but is still plenty good enuf for surveying it yourself.

The tape measure must seem like a new kind of candy to animals.  I have had one
tape measure devoured by a herd of pigs, and another damaged by a dog.

The 200 foot fiberglass tape measure can make quite a Gordian Knot if you aren't
careful.  My suggestion is to coil it up around your elbow and hand.  Tie it
with a piece of twine.  When uncoiling, walk away while feeding tape from the
same side of the coil from which you wound it, Last In First Out [LIFO].

On ground flat and smooth enuf to walk easily, a compass and pace survey is the
ultimate in getting a lot of information for a little trouble.  The 10% error
is acceptable for much preliminary work.  If I have an assistant to keep the
owner occupied, I can usually pace survey while walking around the land the
first time.

Try to pick survey stations which you can find again.  Not every station need
be permanent, but do it whenever convenient.  A gatepost, an unusual tree, a
point of rock, or a piece of pipe pounded into the ground are good permanent
stations.  Flagging ribbon or rags will make a station more obvious.  Temporary
stations need be no more than a scuff mark.  If you blaze trees or make other
permanent marks, be sure that they are in the right place first.  Especially if
they are on someone else's land!

A 300 foot roll of bright orange flagging ribbon is available from CAVE, Inc
for two bux [$2] + $1 shipping & handling.  Other colors, stripes, polka dots,
and flags on wire are available special order.

When permanently marking property lines, it is considered to be in good form to
invite the affected neighbor along.  Bring your camera too.  If it ever comes
before twelve of your peers, then photographs will be worth a lot more than
some mumbo jumbo about compass error.

You need not make the distance between stations the same as did the original
surveyor.  He probably set as few stations as possible.  It takes the boss
about ten minutes of fiddling to get a good set with a transit or undamped
forester's compass.  Then he can relax while the rest of the crew hacks brush
for a half hour.

The Silva Ranger uses no tripod and takes only ten seconds to read.  I usually
read the compass at each tape-length.  You can set up long shots to reduce the
number of compass readings, but it is certainly not worth it.



 SIY11.TXT   Helpful Hints for Surveying in the Real World                  54

The clinometer should be read parallel to the ground.  This means that your
target should be your eyelevel on your assistant.  The tape measure should be
read parallel to the ground too.  The tape should be pulled tight, with just a
little sag.  And don't go around a tree and put a bend in the tape.

If your station is a mark on the ground and you hold the tape at waist height,
then you must read the tape over the station mark.  Drop a pebble or your
pencil from the supposed tape reading and marvel at how far off you can be.  It
takes a lot of tape error to have much effect on your survey, but since this is
a systematic error (all in the same way) you should eliminate it.

You don't need to occupy exactly a station to use it.  Here in backwoods
Kentucky, corners are commonly trees.  It is rather difficult to stand at the
center of a tree!  Unless, of course, the tree is long dead and rotted away.
But then you can't find it.  [You can't win.  You can't break even.  You can't
even get out of the game.  (That's thermodynamics for you!)]

But you can measure as if you were measuring to the center of the tree.  Sight
the compass on the center of the TO tree while standing in front of the FROM
tree.  Measure the TAPE to halfway around the tree.  Have your assistant put
the clinometer target at the proper height alongside of the tree.  Another
handy trick is for both you and your assistant to take a step or few to the
side.  This could enable you to "see thru" some brush, or to get away from a
perturbing fence or hornets' nest.

If you are trying to follow another surveyor, you must be able to find at least
one of his stations.  It need not be the starting station.  Just a station
which you can identify.  You can start anywhere and go in either direction.

If you cannot find any previous station, map the given boundaries of the
parcel.  The resulting map should look pretty much like the map drawn from the
land description in the deed.  The boundary should be made of segments which
intersect at the corners.  From the comparison, you should be able to come
close enuf to find an indication of the corner if there is anything there to
find.

Just because your predecessor was a professional surveyor, don't assume that he
couldn't make a mistake.  While most of today's surveyors check their work for
blunders just like you should do, it wasn't always so.  There are occasional
blunders.  Typograhpic errors, they call 'em.

The old surveys here in the far Boonies of Kentucky are overrun with blunders.
Many were surveyed from the safety and comfort of the owner's front porch, with
the assistance of a jug or three of moonshine.  It is quite possible for you to
be right and for everyone else to be wrong.  It is quite common, actually.

Even if the old surveyor did a good job, there may be copying errors.  I have
noticed that about one new mutation is made in every three deed transcriptions.
 SIY11.TXT   Helpful Hints for Surveying in the Real World                  55

Every station must reference a previous station, or be a fresh start.  But FROM
need not be the previous station, only a previous station.  You can go back and
branch off from any previous station.  When branching, circle the FROM in your
notes so that you will be sure to notice it when plotting.  You can shoot many
stations from a single station, such as the locations of several buildings.

It is possible to have multiple loops in your survey.  These often help to
isolate a blunder to a particular part of the survey.  When calculating
closure, remember that RUN is the distance around the loop in question, not
necessarily the entire distance of the survey.  For instance, you could map the
boundaries, plus the roads, trails, fence lines, streams, buildings, wells, and
cave entrances, as well as any other lines and points of interest.

You need not actually put your assistant on a station to survey it.  A "compass
and guess" station is often sufficient.  You will get good at guessing the tape
after a while.

A station can also be located with compass directions from two other stations,
and no distances.  Measure and plot the directions from the other stations.
Your inaccessible station is where the direction lines cross.

You probably won't want to survey right down a line such as a fence or the
middle of a river.  The fence perturbs the compass; the river perturbs the
surveyor.  Simply survey alongside the line and measure the offset.  Five paces
is a good distance from a wire fence.  Be sure to record which way to the
fence, as well as how far.

It is a simple matter to survey around a hornets' nest or a briar patch.  Just
keep good notes of what you are doing.  You may want to plot field map as you
go along.

If you are trying to survey a straight boundary between two corners, you
needn't concern yourself with surveying a straight line.  Survey wherever
convenient, plot this line on your map, draw your straight line, measure the
offset at each intermediate station, and go back to the field and move your
tentative stations as indicated.  It sounds overly complicated, but it really
is a lot easier done this way.  Use a similar technique to subdivide out a
specific acreage.  Plot a map, survey in the field, repeat until satisfied.

A good next book up is "Compass Land Surveying" by F. Henry Sipe.  See Chapter
14, Sources.  This book is full of useful information without a lot of fancy
mathematics.  The instrument used is the Forester Compass, but most of it is
applicable to the Silva Ranger.  There are good chapters on the legal aspects
of surveying and on problem solving.  Sipe is showing you how to think about
what you are doing; he is not training you to recite magic formulae and
incantations.  A good next book down is "A Layman's Guide to Land Surveying"
also by Sipe.  Here he explains how to hire the right surveyor and how to tell
him what you want done.
 SIY11.TXT   Helpful Hints for Surveying in the Real World                  56

In general, when land is sold, the intent of the seller, rather than the actual
land description, takes precedence.  It is just too easy to blunder when
surveying or typing.

The locations of the corners control the location of the boundary lines.  A
fence may stray from the straight line between corners, but that does not
automatically make the fence line the boundary line.  Of course the adjoining
landowners may agree to call the boundary line any place they choose.  If this
agreed boundary line is much different from the proscribed location, a written
contract should be executed.  Consult your attorney.  If a line is marked and
remains uncontested for a number of years (which varies from state to state),
then there are grounds for adverse possession.

The direction and distance are merely an aid to finding the next corner.  The
actual location of the corner takes precedence over where the "degrees and
poles" run to.  If no one has blundered, then you should be close enuf to
easily find whatever the corner is.  Blazed trees, carved rocks, car axles or
pipe pounded into the ground, and cast concrete posts are good ways to mark
corners so that they may be easily found.

Corners or lines which move, such as a trail junction or a stream bed, may or
may not move the property corner or line.  The general rule is that if the
movement is evolutionary [insidious, gradual and progressive], the boundary
moves also.  If the movement is revolutionary [obvious, sudden and
catastrophic], then the boundary does not move.

If you have any problems in applying the basic surveying method to your
particular situation, ask.  Draw a sketch of what you want to do.  I'm
especially interested in any scientific applications.  This is a good method
for measuring points, lines, areas, or volumes with dimensions ranging from a
few tens of feet to a few miles.  The expected error is about 1% of the
distance.  A mile of survey line should take between about an hour and a day to
complete with a two or three man crew.  Applications range from the exotic to
the mundane.  My particular uses are mapping caves, locating property
boundaries, and setting building foundations.

I can't tell you everything about everything.  Before you holler for help,
THINK about what you are trying to do.  If you want to modify the method, then
you should calculate how this would affect the final survey.  Draw yourself
pictures whenever you get stuck.

And when you are stuck good, it will not be because of something which you
don't know, but rather it will be because of something which you do know that
ain't so.




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There are situations when a 1/2 fast survey simply is not good enuf.  For
disputes, or where a licensed surveyor is mandated by force of law, get a
professional.  Even then, you probably will want to survey it yourself first.
Get all the problems solved and the arguments with the neighbors settled before
the $100 an hour fellow arrives.  You can also keep licensed surveyors honest.

You should agree with the professionals within your limits of error.  If not,
then don't stop asking questions until you know the reason why.  And don't
accept magic as a answer.  Magic is for magicians and shysters and such.  Magic
will get you ripped off.

The hand plotting method with the Silva Ranger compass works well only when the
tape distances on the map are between 0.5 and 3 inches.  If you are using a two
hundred foot tape measure, you cannot accurately plot on an aerial photo or
topo map scale.

You can accurately reduce a larger map on graph paper by the method of
squares.  Select your reduction factor, such as ten times smaller.  Draw big
squares on your map, with each side of the big square the reduction factor
[10x] squares long.  Now sketch your new map on the small squares, using the
map with the big squares as a guide.  Enlargements are done the same way, only
different.  Of course, if you have calculated, rather than plotted with a
compass, then you can plot directly at any scale.  And if you use my CAVEMAP
program on your computer, it might even draw the map on your printer.  An
enlarging/reducing copier can also be used, but it probably won't be able to
make the scale which you want.

If you have the proper sort of mentality, you can see that you could easily
prestidigitate a few numbers in a land description, and no one would be any
wiser.  At least not until after the land was magically stolen, and then it is
too late.  You can see that you don't need to actually walk down a boundary
line to survey it.  You would use a calculator to be sure that everything
closes perfectly, with no embarrassing closure errors to attract suspicion.

Even if you don't have this sort of mentality, others do.  People have been
thinking this way for at least 3500 years.  Moses had something to say about it
in his second book of rules for maintaining a civilized society.  See
Deuteronomy 19:14 & 27:17.

If any of this is still magic after you have practiced a few times (except for
the fact that the red end of the compass needle points North) ask me for a
better explanation.  No magic.  When you make blunders in magic, you can't
catch them.  This makes magic very dangerous.  There should be no magic in your
surveying.  Magic is for magicians and investment advisors.

If you have questions, problems, or just constructive criticism, contact me.

Dave Beiter CAVE Inc 1/2 Fast Road Ritner, KY 42639 606/376-3137