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