mirror of
https://expo.survex.com/repositories/expoweb/.git/
synced 2024-11-25 16:52:00 +00:00
220 lines
12 KiB
HTML
Executable File
220 lines
12 KiB
HTML
Executable File
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0//EN">
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
|
|
<title>1990: Cambridge Underground report</title>
|
|
<link rel="stylesheet" type="text/css" href="../../css/main2.css" />
|
|
</head>
|
|
<body>
|
|
<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">Bräuning
|
|
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>2:18½</td><td>2:+17.5, -17½</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>3:20½</td><td>3:+16, -18</td></tr>
|
|
<tr><td>20-21/7/90</td><td>Pete/Dave F</td><td>Endless</td><td>3:14½,14,13½,14½</td><td>3:+17x4,-18,-18,-17½,-18</td></tr>
|
|
<tr><td>21/7/90</td><td>Francis</td><td>France, FC II</td><td>1:16½</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,-17½</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:+16½,-18.2</td></tr>
|
|
<tr><td>28/7/90</td><td>Olly</td><td>RWS and Belgium</td><td>2:19,18½,18<br>(18,17½,17¾)</td><td>2:+17½,+17½,+17½,<br>-17¼,-17½,-17½<br>(-18,-17½,-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:+16½,-17</td></tr>
|
|
<tr><td>3/8/90</td><td>Tim</td><td>Bolt connections</td><td>1:16,13,14,14½</td><td>1:+17½,+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>2:016½,014,014</td><td>3:+16½,+16,+16½,-17½,-18,-17½</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">Kaninchenhöhle</span> this year, along with 3 others
|
|
down 162, 163 and Two Year Gestation <span lang="de">Höhle.</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° 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° 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">Bräuning
|
|
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 id="links">
|
|
<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>
|
|
<li><a href="../../../index.htm">CUCC Home Page</a></li>
|
|
</ul>
|
|
</body>
|
|
</html>
|