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[svn r6526] Fettled description pages somewhat; also added a survey for 2003 (but missing a scale bar and title box).

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<title>CUCC Expo Rigging Handbook: Artificial belays - bolts</title>
<link rel="stylesheet" type="text/css" href="../../css/main2.css" />
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<h2 id="tophead"> CUCC Expo Rigging Handbook</h2>
<h1>Bolt belays - choosing a location</h1>
<p>Deciding where to put the bolts for a new pitch is something of a black art,
which can be acquired only through much practice and wide experience of SRT in
general. This guide cannot substitute for experience underground.
<!--Particularly as the author has only ever bolted three pitches.
--></p>
<p>Inasmuch as there can be such a thing as a "typical" pitch, the "typical"
rig might be something like this. Start off a traverse line somewhere nice and
far back; often this gives you enough choice of location that you can use a
natural. Approach the pitch-head carefully, gardening as much loose material as
you can before there are cavers or ropes below for it to hit. Look for
somewhere good to place a Y-hang; if the pitch is awkward, this may have to
become a tri-hang - a very typical Expo pitch-head technique is a Y-hang
followed immediately by a deviation, to give full three-dimensional control
over the position of the hang. (Showoffs can achieve the same effect with a
triple bowline, if they know how to tie one.)</p>
<p>Having got the pitch-head bolts in, descend carefully, looking out below you
for any potential rub points, and looking around for good places to rebelay or
deviate. Remember that a deviation to avoid a rub point is only any use if it's
some way above the rub; don't just ab down until it starts rubbing and then
start looking for a rebelay or deviation.</p>
<p>Placing mid-pitch bolts is often a challenging business requiring you to
dangle on miniscule ledges or wedged against the walls while you drill. Don't
overdo it; if it's difficult to put the bolt in, it'll be difficult to rig off
in future. Many seasoned riggers swear by skyhooks as a means of positioning
yourself while you bolt, but don't rely on everyone else who uses the bolt
owning a set! Another trick is to use a borderline natural, which you wouldn't
trust to rig off, to support yourself while you drill.</p>
<p>Some caveats:</p>
<ul class="spacedout">
<li> Watch out for poor rock quality. In most cases the choice of anchor
placements is a compromise between the requirements of the hang and the
necessity of putting your spits into decent rock. Cracks are obviously to be
avoided; mineral veins are also apparently bad, but often there are so many of
these there's no way you can avoid them. Once you've settled on a
likely-looking location, get your hammer out and give the rock a few taps with
the pointy end. It should give a convincing high ringing noise, not a hollow
thud. (The difference in sound is much accentuated by a hammer with a metal
shaft, such as the Petzl bolting hammers, which are expensive but very good;
the club's cheap fibreglass-shafted hammers are rather more difficult in this
respect.)</li>
<li>If your chosen location is in a large block of rock which is well held
together but not well attached to the wall, it can look and sound fine, but
hold a nasty surprise in store. I was once about to start drilling in a
promising-looking location, marred only by a crack in the rock at least 20cm
away from where I wanted to bolt. Some suspicion made me stick the point of my
hammer in the crack and lever on it, at which point a plate of rock about a
metre across and half a metre thick slid off the wall and down the pitch,
taking my proposed spit location with it! Be alert for this sort of thing.</li>
<li>Bear in mind how difficult the rig will be for the user. In most cases, if
it's difficult to rig it'll be difficult to pass and vice versa, but watch out
for subtle gotchas like putting your Y-hangs too low down; this can make the
pitch impossible to get off! Don't force yourself and your companions into
dangerous manouvres like prusiking up one arm of the Y-hang.</li>
<li>When considering how the rope will hang from a particular location, don't
forget to take into account the length of the hanger and maillon. It almost
always needs to be higher up than you expect.</li>
<li>Spits are very much stronger when loaded perpendicular to their axis; so it
is usually best to place spits horizontally into the wall, which is usually the
easiest method anyway. Bear in mind the safe loading angles for the different
types of hanger - only rings, clowns and bollards can take a straight outward
pull. Bends are good for Y-hangs, where the pull is at an angle away from the
wall; twists are best left for straight downward pulls.</li>
</ul>
<hr />
<ul id="links">
<li><a href="../index.htm">Expedition Handbook</a> - Contents
<ul>
<li><a href="index.htm">Rigging Guide</a>
<ul>
<li><a href="intro.htm">Introduction</a></li>
<li>Choosing bolt locations</li>
<li><a href="boltin.htm">The mechanics of placing a bolt</a></li>
<li><a href="exporig.html">Expo-specific rigging tricks</a></li>
</ul></li>
<li><a href="../look4.htm">Prospecting guide</a></li>
<li><a href="../survey/index.htm">Surveying guide</a></li>
<li><a href="../rescue.htm">Rescue guide</a></li>
<li><a href="../photo.htm">Photography guide</a></li>
</ul></li>
<li><a href="../../infodx.htm">Index to info/topics pages</a></li>
<li><a href="../../indxal.htm">Full Index to area 1623</a>
<ul>
<li><a href="../../areas.htm">Area/subarea descriptions</a></li>
</ul></li>
<li><a href="../../index.htm">Back to Expedition Intro page</a></li>
<li><a href="../../../index.htm">Back to CUCC Home page</a></li>
</ul>
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