04 December 2008

Maximising Your Protection

Maximising Your Protection

Maximising Your Protection image

No one likes to fall off, but if you do find yourself plummeting through the air it’s nice to know that the gear you’ve put in is going to stay in. For most climbers their upward movement can be measured by the confidence they have in the protection they leave behind. If the gear won’t go, then neither will most climbers. So in order to climb harder it’s important to understand how to maximize your protection so you can run it out in confidence.

Firstly let’s get one thing clear; 99% of gear you buy is just about indestructible - when new and used correctly. Unless you’re doing something wrong you can’t break full strength (10+kN) wires, cams or karabiners. Most gear failure is due to pilot error; misplaced or incorrectly orientated gear, ignorance and sometimes a little bad luck (or a combination of several of these factors).

The real danger areas are when using very low strength gear (6kN to 2kN) or full strength gear in low strength placements and then asking it to hold a high load fall. This kind of gear includes micro wires, poor fixed runners, super thin tape/cord and micro cams. In these cases you have three options:

1. You can try not to fall off and test how bad it is.
2. You can fall off and find out how bad it is.
3. You can maximize what little strength the gear has so that if you can’t avoid number 1 then you have a better chance that the answer to number 2 won’t be ‘splat’.

THE REALITY OF THE FALL FACTOR

Firstly try and get to grips with what fall factors really mean to you, such as when you’re 20ft out from a prusik loop draped on a bird’s nest. Not wanting to go into fall factors too deeply (check out the excellent Petzl website if you do), it is simply the length of the fall divided by the length of the rope from faller to belayer. But what does this mean?

I once heard someone describe it as the ‘further you fall the heavier you get’, which is true, yet it must be offset by the fact that the more rope you have out, the longer your gear has to absorb this weight due to stretch. This is why a 50-footer on to gear high above the belay is no worse than a five-footer straight on to the belay.

So how does this explain if your gear is going to break? Well it doesn’t. What is more important is something called the shock force curve, which gives you a better understanding of what’s needed in order to keep your gear intact.

SURVIVING THE SHOCK FORCE CURVE

If your gear isn’t to fail, the forces it must hold must remain below the maximum load. This curve is measured by energy and time, with the greater the time the longer the gear has to absorb the energy and hopefully pace out the energy absorption to a safe level. This is why the ‘time stretching’ components of the belay chain - the rope being the primary one - are so crucial in keeping you healthy.

Imagine the shock force curve comparison between two climbers of equal weight falling on to an RP, where one is tied to a 11mm static rope (don’t try it) and another tied to a skinny 8mm dynamic rope. The static transfers the impact almost instantly as it has virtually no elongation, creating a huge peak in the curve which would no doubt go way beyond the maximum strength of the RP. The thin rope on the other hand, applies the force over a longer space of time and so the peak force is greatly reduced with the force being transferred gradually. The falling climber does not get lighter, only the speed at which the RP has to catch him.

The more rope you have out the softer the fall i.e. the longer the piece has to absorb the impact and so the lower the shock force curve. It is for this reason that the double rope system is by far the best rope system to employ for thinly protected climbs, having much higher shock absorbency (low impact force) than single ropes and even the ability to spread the load over two runners at the same time (two parallel runners clipped on separate ropes).

One thing that many climbers fail to understand is that to best employ the rope’s low impact force you need to maximize its elongation, so that it’s allowed to stretch as far as possible. If the ropes are running through several acute angles, where they are poorly extended, then this will increase the impact force on the gear as this will reduce its ability to stretch due to friction. In order to limit this, make sure you have plenty of longish extenders and slings and avoid the tendency to always go for shorty extenders because you’re scared of falling an extra 10cm or so.

Two other important relatively new pieces of gear that will also increase safety on poor gear is the shock absorbing sling and DMM Revolver karabiner. The DMM Revolver is a revolutionary wire gated karabiner that features a 11mm pulley wheel built into the body of the karabiner and is designed to radically reduce rope drag. This not only lowers the effort required to pull a rope across the body of the karabiner - saving strength - it also means that the rope will run easier in a fall. This has the effect of passing on more of the energy to the rope and the belayer below (the energy used to lift your belayer is energy your pro isn’t taking). Although I don’t really consider the Revolver as an all-round design (due to cost and weight), it is a valuable tool and is a useful addition to any rack and highly recommended (plus it has several rescue uses as well).

Although many climbers still view shock absorbing slings (also known as screamers or ripper slings), as the sole preserve of the winter climber they are, in fact, of more use to the rock-climber, because they are the ones who do far more falling. The psychological protection a shock absorbing sling provides can be immense and is reason enough to use them in my book alone.

The actual improvement in the chances of that piece not failing has always been hard to define. Originally some climbers pointed out that by giving a dynamic belay - letting some rope slip through the belay plate - the same effect could be achieved. Unfortunately in all but the most perfect situation this often proves impossible, as the natural reaction in a fall is for the second to lock off the plate, especially with modern rope grabbing belay devices (compared to Figure 8 and Munter Hitch belaying) and so shock absorbing slings are increasingly useful for clipping low strength gear.

Above, the crucial (and only) gear on John Arran’s E10, Doctor Dolittle. Two of the pieces of gear were places with the expectation that they would ‘fail’, reducing the force on the crucial hand placed peg.

What the shock absorbing sling does is to lower the shock force curve further by extending the time in which the energy can be absorbed and help to extend this absorption period, as the stitches rip apart, keeping the destructive peak forces lower. So does it really work? Because the average activation is around 3kN (300k) a ripper will not make a bad piece good, but it will make a good but weak piece like an RP3, micro cam or a rusty fixed peg better, especially as part of your ‘time stretching’ components.

HOW AND WHERE SHOULD RIPPER SLINGS BE USED?

Rippers should be used on any ground where poor gear will be encountered, whatever the grade, rock, ice or mixed. For most rock-climbing one or two slings should be more than enough, with more being carried in winter. Shock absorbers can also be used on belays, with the gear being equalized, then connected to the belayer via a ripper sling (use two screwgates if this is your only attachment). A ripper sling, when fully activated, is still full strength.

A crucial point to remember with ripper slings is that due to the vibration caused by the ripping stitches sticking, wiregate krabs should be used on both ends to limit gate chatter. If nothing more, a ripper gives a mental boost when used with marginal placements and for belays. But don’t delude yourself about their magical powers. Remember it won’t make a bad placement good but it will make a marginally good placement better.

MICRO GEAR

Micro gear has very little surface contact and so it’s imperative that the placement is as good as it can be. Knowing and understanding the strength rating on the gear and what high loads will do to it are crucial. Most people don’t realize that a wire with a 2kN breaking strain can be broken with just a hard yank and although the wire might not break the nut may deform long before that or pull through the rock itself. Learn how to place gear in series, equalizing several bad pieces to make one good one. Never be afraid to place two or more pieces at the beginning of a hard section (it’s your neck) always equalizing them if you can. Three well-equalized 3kN RPs could create a single 9kN piece (give or take a kN or so) and looking down on a nest of gear may give you the mettle not to jibber and fall off in the first place.

 

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