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<center><font size=-1>CTS 91.1327/e: Cambridge Underground 1991 pp 24-27</font>
<h2>Surveying Report Part I - Calibration</h2>
<p><b>Wookey</b></center>
<p>The standard of CUCC surveying continues to improve as interest in the
subject increases. This year we introduced instrument calibration and on-site
survey computation and display, as well as continuing the process of
educating the masses to the best and worst ways to survey. The calibration
was in order to justify our claims of Grade 5 surveying, and the computer was
both to relieve the tedium of doing the number crunching with programmable
calculators and of plotting the results by hand.
<p>Calibration for each trip/person/instrument combination should give data
on instrument zero errors, eyesight parallax errors, and local magnetic
variation. In actuality it did give some interesting results but failed to
prove very much beyond the fact that no-one can take accurate compass
readings above about 15 degrees of tilt, and that one of the clinos is about
half a degree out. The system used was to build two cairns, one just by the
161(a) entrance and one about 20 metres away along the ridge, then paint the
tips of both to avoid confusion over exactly which points to use. These
cairns were (ideally) used by each instrument reader before each trip for a
compass reading from bottom to top and for clino readings both ways. A
compass reading from the bottom cairn to the <span lang="de-at">Br&auml;uning
Nase</span> was also taken in some cases. All readings were preferably read
several times to give an indication of repeatability, and to improve
accuracy. The position of the bottom cairn was determined by taking bearings
on surrounding hills.
<p>This calibration, whilst not being carried out on every trip, was done
sufficiently often to give some interesting results.
<table border=2>
<tr><th>Date</th><th>Insts</th><th>Where</th><th>Comp</th><th>Clino</th></tr>
<tr><td>12/7/90</td><td>Juliette/Wook</td><td>Adrians-161b</td></tr>
<tr><td>13/7/90</td><td>Jeremy</td><td>2 Year Gestation</td><td>2</td><td>4</td></tr>
<tr><td>14/7/90</td><td>Julian</td><td>Pit and Pendulum</td><td>4:15,13,14</td><td>4:+17,+17,-17,-17</td></tr>
<tr><td>14/7/90</td><td>Matt</td><td>Rabbit Warren</td><td>1</td><td>2</td></tr>
<tr><td>18/7/90</td><td>William</td><td>Flat Battery</td><td>1</td><td>1</td></tr>
<tr><td>18-19/7/90</td><td>Jeremy</td><td>Bullshit alley</td><td>3</td><td>3</td></tr>
<tr><td>18-19/7/90</td><td>Dave F</td><td>Vestabule, CFN</td><td>2:18&frac12;</td><td>2:+17.5, -17&frac12;</td></tr>
<tr><td>19/7/90</td><td>Animal</td><td>Dreamtime</td><td>1</td><td>1</td></tr>
<tr><td>19-20/7/90</td><td>Del</td><td>Too Much</td><td>3:20&frac12;</td><td>3:+16, -18</td></tr>
<tr><td>20-21/7/90</td><td>Pete/Dave F</td><td>Endless</td><td>3:14&frac12;,14,13&frac12;,14&frac12;</td><td>3:+17x4,-18,-18,-17&frac12;,-18</td></tr>
<tr><td>21/7/90</td><td>Francis</td><td>France, FC II</td><td>1:16&frac12;</td><td>1:+17, -17</td></tr>
<tr><td>21/7/90</td><td>Mark D</td><td>Flat Battery</td><td>3:20</td><td>3:+17,-17&frac12;</td></tr>
<tr><td>22/7/90</td><td>Dave H</td><td>Splatdown</td><td>2</td><td>2</td></tr>
<tr><td>24/7/90</td><td>Pete?</td><td>Umleitung</td><td>1:12,12,13,13,12</td><td>1:+17,+17,+17, -17,-17,-17</td></tr>
<tr><td>26/7/90</td><td>Jeremy</td><td>FB Phreatic</td><td>3:16</td><td>3:+17,-18</td></tr>
<tr><td>28/7/90</td><td>Matt</td><td>Vd1-2YG-161b/c</td><td>2:</td><td>4:</td></tr>
<tr><td>28/7/90</td><td>Dave</td><td>163/Surface</td><td>3:16</td><td>3:+16&frac12;,-18.2</td></tr>
<tr><td>28/7/90</td><td>Olly</td><td>RWS and Belgium</td><td>2:19,18&frac12;,18<br>(18,17&frac12;,17&frac34;)</td><td>2:+17&frac12;,+17&frac12;,+17&frac12;,<br>-17&frac14;,-17&frac12;,-17&frac12;<br>(-18,-17&frac12;,-17,+17,+17,+17)</td></tr>
<tr><td>29/7/90</td><td>Dave F</td><td>162</td><td>2:16,16</td><td>3:16.3,-18</td></tr>
<tr><td></td><td>Dave F</td><td>Captive Wedge</td><td>1:16</td><td>1:+16&frac12;,-17</td></tr>
<tr><td>3/8/90</td><td>Tim</td><td>Bolt connections</td><td>1:16,13,14,14&frac12;</td><td>1:+17&frac12;,+17,-17</td></tr>
<tr><td>5/8/90</td><td>Dave F</td><td>Adrian bolts</td></tr>
<tr><td></td><td>Paul</td><td>161b-161c</td><td>4</td><td>2</td></tr>
<tr><td>6/8/90</td><td>Dave F</td><td>Sheared off KB</td><td>1</td><td>1</td></tr>
<tr><td>6/8/90</td><td>Tim</td><td>Powerstation</td><td>2:016&frac12;,014,014</td><td>3:+16&frac12;,+16,+16&frac12;,-17&frac12;,-18,-17&frac12;</td></tr>
</table>
<pre>
Compass numbers: 1 624931 Clino numbers: 1 736380
2 721899 2 240641
3 543693 3 726974
4 949847 4 716221
</pre>
<p>There were 22 Surveying trips in
<span lang="de">Kaninchenh&ouml;hle</span> this year, along with 3 others
down 162, 163 and Two Year Gestation <span lang="de">H&ouml;hle.</span>
<p>Right - what did all this lovely data show us? Plotting the readings for
each clino (see graphs overleaf) was quite instructive as they were all
pretty consistent and one of the clinos is obviously about 0.7&deg; off its
zero. The compass data is much less conclusive. These results are very
scattered, despite the fact that the results for one individual are usually
consistent. So much so that nothing can reasonably be decided about their
zero accuracy. I think the variation shows just how inaccurate readings taken
at inclinations above 15&deg; are. Note that even the only readings taken by
the same person with the same compass are different. Conversely the
relatively few readings taken on the <span lang="de-at">Br&auml;uning
Nase</span> were much more consistent (presumably because they were nearly
horizontal).
<p>In the light of the above, next year's compass calibration will be done
more horizontally to see if more meaningful results can be obtained.
<p><center><img alt="Calibration data summary (graphical) - 13k png"
width=614 height=966 src="calib.png"></center>
<p>The computer used this year was Wadders' Archimedes. This did a sound but
phenomenally slow job of pretending to be a PC in order to run Sean Kelly's
Surveyor '88 ('89 version). After much faffing with discs to get the software
working, the system proved very useful as the survey data was entered as soon
as it came down the hill (we didn't quite resort to radioing the data down!)
and so centre lines of new passage were immediately available for the
original surveyors to check for errors. Olly's program to improve the display
end of the process also helped as its real-time rotation provided much better
comprehension of the displayed passage than was possible otherwise.
<p>This almost instant and versatile graphical display of the survey data was
helpful in allowing visualization of the relative positions of different bits
of cave. A system which showed some sort of representation of the walls as
well would be even better and a prototype may be available for use on Austria
'92.
<p>Whilst on the subject of surveying, and having just drawn up the survey,
here is probably the best place to mention various criticisms of surveying
technique which have become apparent this year, mostly highlighted by the
overall improvement in standards.
<p>When surveying pitches all plans that have no means of identifying their
orientation are practically useless. Either a bearing or more than one survey
point is needed. Also, when surveying vertically, think of the whole process
as having tipped through 90 degrees along with the cave, so each little plan
becomes a 'cross section' and you should draw elevations of the whole thing,
instead of a horizontal plan. These elevations are obviously likely to have
lots of dotted lines, but if you don't draw something the survey drawer is
just going to have to guess which is not too hot.
<p>Along similar lines it is also extremely useful to draw an extended
elevation along the line of the survey/ passage. This effectively fills in
the third dimension and again saves the drawer guessing what is between each
cross-section. Hardly anyone in CUCC has done much of this so far, so it will
be a new thing for you all to forget to do in future.
<p>Fortunately for you lot I have lost my list of specific survey whinges
which named names and pointed fingers so ... Ah, no, here it is. Now, I don't
want anyone to take this too personally and feel pilloried or whatever. I
just think that the best way for people to improve is to get some
constructive criticism, and all you newies can see what everybody else did
badly and try to avoid making the same mistakes.
<p>So here goes:
<p>Starting with the couple of things mentioned above. Those guilty of
unaligned pitch plans are Olly and Tim (Powerstation), Jeremy and Dave F
(Captive Wedge et al.), Del and Dave H (Splatdown) and Wookey (Vestabule and
163). As already mentioned no-one did any extended elevations except bits by
Francis (Bullshit Alley), Wookey (Vestabule), Tina (Dreamtime), Hugh (French
Connection II) and Matt/ Pete <span lang="de">(Umleitung).</span>
<p>Now I know that LRUD (Left, Right, Up, Down) data is a slightly
contentious issue, but unless you are going to draw cross-sections at each
survey station, you should write down the LRUD information as it defines the
position of the station in the passage. One point which seems to be unclear
about LRUD is exactly what distances to give. You should aim to define the
distance of the station from the general outline of the passage, ignoring
small-scale twiddly bits. Where a reading is meaningless (eg. you are at a
junction and there is no sensibly defined left wall) then put a dash, where
you don't know (eg. the roof is too high to see) then put a question mark.
In cases where LRUD would be misleading (eg. where there is a significant
floor trench) then an annotated cross-section will be much clearer. Also
note that left and right are normally defined looking in the direction of the
survey.
<p>Those guilty of not including LRUD information this year are Pete, Matt
(and he didn't have any point descriptions either), Dave H, Hugh and Tina.
Also on the subject of sections Dave H and Francis should make sure they've
got scales/sizes on all of theirs and Juliette should try to keep hers to
scale (next year's squared paper should help).
<p>Other complaints are: Hugh and Juliette should write their information in
compass, clino, tape order instead of the more usual tape, compass, clino
that everybody else uses (whilst this is not actually wrong, unless there is
a good reason for it it should be avoided as it is just another source of
confusion and error); Wookey should put more distances on his plans and
elevations; Juliette should try to write ones and sevens so they can't be
confused; Hugh wins the prize for general inaccuracy; and Tina should put
more (some) passage detail in (pitches, bolts, ropes, climbs, sand etc).
<p>Right, that's all for this year.
<p>The other thing which has come to my notice (through Welsh surveying) is
that as well as compasses being affected by alkaline batteries, some Joe
Brown style helmets have something in their rim which can give a good 17
degrees of error - try yours.
<p>I will just end all this ranting by thanking all those who put in cold,
tedious hours underground in the interests of science(?), and suggest that
you think back to the surveying CUCC was doing just three years ago and how
much we have improved since then. No longer will we be in 'How to run a
caving Expo' as the least scientific expo known to man!
<hr />
<!-- LINKS -->
<ul>
<li>Cambridge Underground 1991,
<a href="../../../jnl/1991/index.htm">Table of Contents</a></li>
<li>Surveying Report:
<ul>
<li><a href="svy2.htm"> 2: Survey Production</a></li>
</ul></li>
<li>Other 1990 Expedition info:
<ul>
<li><a href="index.htm">Index</a> (more detail than in this list)</li>
<li><a href="log.htm">Logbook</a></li>
<li><a href="report.htm">Expo Report</a> (Diary)</li>
<li><a href="cavegd.htm">161 Description</a> to date (ie. 1990)</li>
<li><a href="162163.htm">Entrances 162 and 163</a></li>
<li><a href="newent.htm">New Entrances</a></li>
<li>Bosch Cordless Rotary Hammer <a href="drill.htm">Drill Report</a></li>
<li><a href="sponsr.htm">Sponsors</a></li>
</ul></li>
<li><a href="../../pubs.htm#pubs1990">Index</a> to all publications</li>
<li><a href="../../index.htm">Back to Expeditions intro page</a></li>
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