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<title>1990: Cambridge Underground report</title>
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<center><font size=-1>CTS 91.1327/e: Cambridge Underground 1991 pp 24-27</font>
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<h2>Surveying Report Part I - Calibration</h2>
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<p><b>Wookey</b></center>
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<p>The standard of CUCC surveying continues to improve as interest in the
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subject increases. This year we introduced instrument calibration and on-site
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survey computation and display, as well as continuing the process of
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educating the masses to the best and worst ways to survey. The calibration
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was in order to justify our claims of Grade 5 surveying, and the computer was
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both to relieve the tedium of doing the number crunching with programmable
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calculators and of plotting the results by hand.
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<p>Calibration for each trip/person/instrument combination should give data
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on instrument zero errors, eyesight parallax errors, and local magnetic
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variation. In actuality it did give some interesting results but failed to
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prove very much beyond the fact that no-one can take accurate compass
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readings above about 15 degrees of tilt, and that one of the clinos is about
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half a degree out. The system used was to build two cairns, one just by the
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161(a) entrance and one about 20 metres away along the ridge, then paint the
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tips of both to avoid confusion over exactly which points to use. These
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cairns were (ideally) used by each instrument reader before each trip for a
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compass reading from bottom to top and for clino readings both ways. A
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compass reading from the bottom cairn to the <span lang="de-at">Bräuning
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Nase</span> was also taken in some cases. All readings were preferably read
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several times to give an indication of repeatability, and to improve
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accuracy. The position of the bottom cairn was determined by taking bearings
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on surrounding hills.
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<p>This calibration, whilst not being carried out on every trip, was done
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sufficiently often to give some interesting results.
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<table border=2>
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<tr><th>Date</th><th>Insts</th><th>Where</th><th>Comp</th><th>Clino</th></tr>
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<tr><td>12/7/90</td><td>Juliette/Wook</td><td>Adrians-161b</td></tr>
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<tr><td>13/7/90</td><td>Jeremy</td><td>2 Year Gestation</td><td>2</td><td>4</td></tr>
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<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>
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<tr><td>14/7/90</td><td>Matt</td><td>Rabbit Warren</td><td>1</td><td>2</td></tr>
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<tr><td>18/7/90</td><td>William</td><td>Flat Battery</td><td>1</td><td>1</td></tr>
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<tr><td>18-19/7/90</td><td>Jeremy</td><td>Bullshit alley</td><td>3</td><td>3</td></tr>
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<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>
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<tr><td>19/7/90</td><td>Animal</td><td>Dreamtime</td><td>1</td><td>1</td></tr>
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<tr><td>19-20/7/90</td><td>Del</td><td>Too Much</td><td>3:20½</td><td>3:+16, -18</td></tr>
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<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>
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<tr><td>21/7/90</td><td>Francis</td><td>France, FC II</td><td>1:16½</td><td>1:+17, -17</td></tr>
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<tr><td>21/7/90</td><td>Mark D</td><td>Flat Battery</td><td>3:20</td><td>3:+17,-17½</td></tr>
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<tr><td>22/7/90</td><td>Dave H</td><td>Splatdown</td><td>2</td><td>2</td></tr>
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<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>
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<tr><td>26/7/90</td><td>Jeremy</td><td>FB Phreatic</td><td>3:16</td><td>3:+17,-18</td></tr>
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<tr><td>28/7/90</td><td>Matt</td><td>Vd1-2YG-161b/c</td><td>2:</td><td>4:</td></tr>
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<tr><td>28/7/90</td><td>Dave</td><td>163/Surface</td><td>3:16</td><td>3:+16½,-18.2</td></tr>
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<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>
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<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>
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<tr><td></td><td>Dave F</td><td>Captive Wedge</td><td>1:16</td><td>1:+16½,-17</td></tr>
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<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>
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<tr><td>5/8/90</td><td>Dave F</td><td>Adrian bolts</td></tr>
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<tr><td></td><td>Paul</td><td>161b-161c</td><td>4</td><td>2</td></tr>
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<tr><td>6/8/90</td><td>Dave F</td><td>Sheared off KB</td><td>1</td><td>1</td></tr>
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<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>
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</table>
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<pre>
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Compass numbers: 1 624931 Clino numbers: 1 736380
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2 721899 2 240641
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3 543693 3 726974
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4 949847 4 716221
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</pre>
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<p>There were 22 Surveying trips in
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<span lang="de">Kaninchenhöhle</span> this year, along with 3 others
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down 162, 163 and Two Year Gestation <span lang="de">Höhle.</span>
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<p>Right - what did all this lovely data show us? Plotting the readings for
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each clino (see graphs overleaf) was quite instructive as they were all
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pretty consistent and one of the clinos is obviously about 0.7° off its
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zero. The compass data is much less conclusive. These results are very
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scattered, despite the fact that the results for one individual are usually
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consistent. So much so that nothing can reasonably be decided about their
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zero accuracy. I think the variation shows just how inaccurate readings taken
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at inclinations above 15° are. Note that even the only readings taken by
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the same person with the same compass are different. Conversely the
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relatively few readings taken on the <span lang="de-at">Bräuning
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Nase</span> were much more consistent (presumably because they were nearly
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horizontal).
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<p>In the light of the above, next year's compass calibration will be done
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more horizontally to see if more meaningful results can be obtained.
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<p><center><img alt="Calibration data summary (graphical) - 13k png"
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width=614 height=966 src="calib.png"></center>
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<p>The computer used this year was Wadders' Archimedes. This did a sound but
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phenomenally slow job of pretending to be a PC in order to run Sean Kelly's
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Surveyor '88 ('89 version). After much faffing with discs to get the software
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working, the system proved very useful as the survey data was entered as soon
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as it came down the hill (we didn't quite resort to radioing the data down!)
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and so centre lines of new passage were immediately available for the
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original surveyors to check for errors. Olly's program to improve the display
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end of the process also helped as its real-time rotation provided much better
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comprehension of the displayed passage than was possible otherwise.
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<p>This almost instant and versatile graphical display of the survey data was
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helpful in allowing visualization of the relative positions of different bits
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of cave. A system which showed some sort of representation of the walls as
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well would be even better and a prototype may be available for use on Austria
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'92.
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<p>Whilst on the subject of surveying, and having just drawn up the survey,
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here is probably the best place to mention various criticisms of surveying
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technique which have become apparent this year, mostly highlighted by the
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overall improvement in standards.
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<p>When surveying pitches all plans that have no means of identifying their
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orientation are practically useless. Either a bearing or more than one survey
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point is needed. Also, when surveying vertically, think of the whole process
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as having tipped through 90 degrees along with the cave, so each little plan
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becomes a 'cross section' and you should draw elevations of the whole thing,
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instead of a horizontal plan. These elevations are obviously likely to have
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lots of dotted lines, but if you don't draw something the survey drawer is
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just going to have to guess which is not too hot.
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<p>Along similar lines it is also extremely useful to draw an extended
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elevation along the line of the survey/ passage. This effectively fills in
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the third dimension and again saves the drawer guessing what is between each
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cross-section. Hardly anyone in CUCC has done much of this so far, so it will
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be a new thing for you all to forget to do in future.
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<p>Fortunately for you lot I have lost my list of specific survey whinges
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which named names and pointed fingers so ... Ah, no, here it is. Now, I don't
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want anyone to take this too personally and feel pilloried or whatever. I
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just think that the best way for people to improve is to get some
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constructive criticism, and all you newies can see what everybody else did
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badly and try to avoid making the same mistakes.
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<p>So here goes:
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<p>Starting with the couple of things mentioned above. Those guilty of
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unaligned pitch plans are Olly and Tim (Powerstation), Jeremy and Dave F
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(Captive Wedge et al.), Del and Dave H (Splatdown) and Wookey (Vestabule and
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163). As already mentioned no-one did any extended elevations except bits by
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Francis (Bullshit Alley), Wookey (Vestabule), Tina (Dreamtime), Hugh (French
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Connection II) and Matt/ Pete <span lang="de">(Umleitung).</span>
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<p>Now I know that LRUD (Left, Right, Up, Down) data is a slightly
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contentious issue, but unless you are going to draw cross-sections at each
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survey station, you should write down the LRUD information as it defines the
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position of the station in the passage. One point which seems to be unclear
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about LRUD is exactly what distances to give. You should aim to define the
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distance of the station from the general outline of the passage, ignoring
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small-scale twiddly bits. Where a reading is meaningless (eg. you are at a
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junction and there is no sensibly defined left wall) then put a dash, where
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you don't know (eg. the roof is too high to see) then put a question mark.
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In cases where LRUD would be misleading (eg. where there is a significant
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floor trench) then an annotated cross-section will be much clearer. Also
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note that left and right are normally defined looking in the direction of the
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survey.
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<p>Those guilty of not including LRUD information this year are Pete, Matt
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(and he didn't have any point descriptions either), Dave H, Hugh and Tina.
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Also on the subject of sections Dave H and Francis should make sure they've
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got scales/sizes on all of theirs and Juliette should try to keep hers to
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scale (next year's squared paper should help).
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<p>Other complaints are: Hugh and Juliette should write their information in
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compass, clino, tape order instead of the more usual tape, compass, clino
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that everybody else uses (whilst this is not actually wrong, unless there is
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a good reason for it it should be avoided as it is just another source of
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confusion and error); Wookey should put more distances on his plans and
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elevations; Juliette should try to write ones and sevens so they can't be
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confused; Hugh wins the prize for general inaccuracy; and Tina should put
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more (some) passage detail in (pitches, bolts, ropes, climbs, sand etc).
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<p>Right, that's all for this year.
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<p>The other thing which has come to my notice (through Welsh surveying) is
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that as well as compasses being affected by alkaline batteries, some Joe
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Brown style helmets have something in their rim which can give a good 17
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degrees of error - try yours.
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<p>I will just end all this ranting by thanking all those who put in cold,
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tedious hours underground in the interests of science(?), and suggest that
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you think back to the surveying CUCC was doing just three years ago and how
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much we have improved since then. No longer will we be in 'How to run a
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caving Expo' as the least scientific expo known to man!
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<hr />
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<!-- LINKS -->
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<ul id="links">
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<li>Cambridge Underground 1991,
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<a href="http://cucc.survex.com/jnl/1991/index.htm">Table of Contents</a></li>
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<li>Surveying Report:
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<ul>
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<li><a href="svy2.htm"> 2: Survey Production</a></li>
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</ul></li>
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<li>Other 1990 Expedition info:
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<ul>
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<li><a href="index.htm">Index</a> (more detail than in this list)</li>
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<li><a href="log.htm">Logbook</a></li>
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<li><a href="report.htm">Expo Report</a> (Diary)</li>
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<li><a href="cavegd.htm">161 Description</a> to date (ie. 1990)</li>
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<li><a href="162163.htm">Entrances 162 and 163</a></li>
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<li><a href="newent.htm">New Entrances</a></li>
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<li>Bosch Cordless Rotary Hammer <a href="drill.htm">Drill Report</a></li>
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<li><a href="sponsr.htm">Sponsors</a></li>
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</ul></li>
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<li><a href="../../pubs.htm#pubs1990">Index</a> to all publications</li>
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<li><a href="../../index.htm">Back to Expeditions intro page</a></li>
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<li><a href="../../../index.htm">CUCC Home Page</a></li>
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</ul>
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