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fix a link in survey/how and provide some other notes on scale drawing.

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also begin splitting up hints into stuff more or less relevant to modern
instruments.
This commit is contained in:
echarlie
2022-03-31 11:09:23 -04:00
parent 03aae39788
commit cbfeb30e6d
2 changed files with 51 additions and 36 deletions
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72
handbook/survey/hints.htm
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@@ -8,37 +8,18 @@
<h2 id="tophead">CUCC Expo Surveying Handbook</h2>
<h1>Wookey's hints and tips</h1>
<p>... to save you going back to do it again.
<p>... to save you going back to do it again.</p>
<p><i>"hmm - not going to finish this even slightly, so some points to bear
in mind:"</i></p>
<ul>
<li>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.</li>
<li>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.</li>
<li>Practice using the compass above ground to avoid classic errors like
reading 56 as 64 (ie. counting the wrong way from the 60 marker).</li>
<li>Degrees are on the <b>left hand</b> 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.</li>
<li>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 <em>past</em> the bolt.</li>
<li>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
@@ -59,16 +40,6 @@ might get rubbed off.</li>
<li>Take at least one spare pencil!</li>
<li>Return instuments to the 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.</li>
<li>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 <em>have</em> to use it, but can't
actually take readings <i>from</i> it.</li>
<li>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
@@ -80,10 +51,6 @@ 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.</li>
<li>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!</li>
<li>Record the serial numbers of instruments (comp/clino/tape). Also write
down dates, endpoints, surveyors, cave, any conventions used for symbols,
passage widths etc.</li>
@@ -93,6 +60,43 @@ 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).</li>
</ul>
<h3>If using analogue instruments (i.e. Suunto)</h3>
<ul>
<li>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.</li>
<li>Practice using the compass above ground to avoid classic errors like
reading 56 as 64 (ie. counting the wrong way from the 60 marker).</li>
<li>Degrees are on the <b>left hand</b> 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.</li>
<li>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 <em>past</em> the bolt.</li>
<li>Return instuments to the 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.</li>
<li>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 <em>have</em> to use it, but can't
actually take readings <i>from</i> it.</li>
<li>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!</li>
<li>Calibration is useful at 161a: ie. compass from lower to upper cairn, and
from lower cairn to Br&auml;uning Zinken (if you know where it is - highest
point near right-hand edge of Br&auml;uning Wall (just over the bush!)). See