CUCC Expo Rigging Handbook

Bolt belays - choosing a location

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.

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.)

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.

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.

Some caveats:

• 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.)
• 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.
• 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.
• 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.
• 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.