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115 lines
5.2 KiB
HTML
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<title>CUCC Expo Surveying Handbook: Hints & tips</title>
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<h2 id="tophead">CUCC Expo Surveying Handbook</h2>
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<h1>Wookey's hints and tips</h1>
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<p>... to save you going back to do it again.
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<p><i>"hmm - not going to finish this even slightly, so some points to bear
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in mind:"</i></p>
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<ul>
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<li>The compass must be held level to get a meaningful reading. A left/right
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tilt will cause a systematic over or under reading, whilst sighting up or
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down a steep leg may cause the compass to stick. It is easier to sight from
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the lower station by keeping the tape in position and sighting along it.</li>
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<li>Take care with lights, batteries, helmets and anything else which could
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be magnetic - check your gear on the surface, or your work could be seriously
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impaired. If your light affects the compass, then hold it away from the
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instrument when lighting it. Keep the compass well away from steel objects
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like bolts, steel karabiners or maillons, tripods or ammo cans when sighting.</li>
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<li>Practice using the compass above ground to avoid classic errors like
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reading 56 as 64 (ie. counting the wrong way from the 60 marker).</li>
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<li>Degrees are on the <b>left hand</b> scale on clinos. The other scale is
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percent gradient - this is better than nothing if you can't read the degree
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scale (make it abundantly clear in the notes), but reading the wrong one
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without realising gives useless results.</li>
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<li>Pick survey points so you can get your head in, and so you can see both
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ways as easily as possible. Note that Bolts are good things to use as
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stations (because we can find them again), but don't put the compass within
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30cm as it will give joke readings. Sight from the other end of the leg, or
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put the compass behind it and look <em>past</em> the bolt.</li>
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<li>Write decimal points as slashes to stop them getting lost in the mud.
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Make sure they don't look like "1"s. It is helpful to always write compass
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readings as three digits before the decimal point, and clino as two digits
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with a sign. Add leading zeroes if needed (eg. 031/5 +02/5).</li>
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<li>"Notes" should call back readings to "Instruments" to check. Make sure
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you call out what you have written, not what you heard. It helps to ensure
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both of you have brains in gear if you change the format. Eg. "Instruments"
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calls out "Compass thirty seven point five", and "Notes" calls back "Oh,
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three, seven point five, compass".</li>
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<li>Instead of writing all the data on one sheet, and the sketches on
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another, you may like to write all the info for a few legs on the same sheet
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so that mud does not accumulate on one important data sheet in grubby areas.</li>
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<li>Have a separate front sheet without anything important on otherwise it
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might get rubbed off.</li>
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<li>Take at least one spare pencil!</li>
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<li>Return instuments to the carbide dessicator before you fall asleep
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otherwise they are likely to fog up the next time. Don't leave them in the
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cave, both for the above reason and because the next survey may need them
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somewhere else entirely.</li>
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<li>Leapfrogging is a good idea in general but you don't have to be religious
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about it. It is almost impossible in tiny passage, and sometimes a point for
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a survey station is so obvious that you <em>have</em> to use it, but can't
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actually take readings <i>from</i> it.</li>
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<li>Draw plans and extended elevations in horizontal bits of cave, with
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cross sections for each typical section of passage. Orientate your cross
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sections (ie. show which direction they are looking) on the plans. It helps
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always to do the cross sections looking in a consistent direction.</li>
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<li>Draw extended sections in two directions for vertical cave, with plans
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where required. Mark directions on plans and sections otherwise they are
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impossible to orientate later. A plan with only one station and no direction
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indicator cannot be orientated. It is easiest if the drawer takes a spare
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compass for this (doesn't have to be a good one) in vertical work.</li>
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<li>Think ahead when surveying pitches, especially long ones. Take two tape
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measures for stuff over 30m, or three well-organised people and some handy
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big croc-clips!</li>
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<li>Record the serial numbers of instruments (comp/clino/tape). Also write
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down dates, endpoints, surveyors, cave, any conventions used for symbols,
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passage widths etc.</li>
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<li>Find out where you are going to join your survey to <b>before</b> you go,
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otherwise your surveys will be left hanging in space. From 1996, the QM
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list is supposed to tell you the nearest existing survey station - make
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sure that you can identify this (look at the relevant year's survey book).</li>
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<li>Calibration is useful at 161a: ie. compass from lower to upper cairn, and
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from lower cairn to Bräuning Zinken (if you know where it is - highest
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point near right-hand edge of Bräuning Wall (just over the bush!)). See
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the "<a href="../findit.htm">Taking bearings</a>" doc for photos. Clino
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from lower to upper cairn and back down. Several readings for each
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calibration is best.</li>
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<li>Take care when holding your survey notes when using a carbide - they
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catch fire very easily (a friend of mine lost over 300m of survey notes in
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Mulu once like that - Andy F)</li>
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</ul>
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<p>that'll do for now – wook</p>
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<hr />
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