So, we have covered the idea of ladders as a tool for accessing minor pitches of 10 metres or less. But what happens if it is 20 metres? Or 50? or 603 metres (The world’s deepest underground pitch is 603 m in Vrtoglavica Cave, Slovenia).
The answer is SRT – Single Rope Technique (often referred to as vertical caving). Put simply, this is a way of descending and ascending pitches using only 1 rope with no need for another belay.
Before reading onwards, take a quick look at http://en.wikipedia.org/wiki/Single_Rope_Technique
This is done by abseiling, in the same manner as many rock climbers do, and many commercial outdoor rec companies do things like Adventure Guides Australia’s huge 200m abseils at Mt. Buffalo, etc. So, it is not specific to Caving. The first ever abseiling was done by putting a rope around your body and hoping for the best (often with a belay). This was until mechanical descenders and ascenders were invented, which happened roughly at the end of the second world war, although modern day SRT was developed long after that.
There are a number of tools you can use to abseil. The simplest three are a bobbin, a stitch plate (which can also be used to belay climbers on ladders), or you can even abseil on a munter hitch knot tied around a carabiner (twists the hell out of the rope). A lot of people in caving do use a bobbin, often a Petzl ‘Simple’.
However, most cavers in Victoria (and probably the world) use a STOP descender. This is like a bobbin but it has an auto break feature, so if you let go of the handle you stop. This has several advantages.
One is that if you become unconscious for any reason you won’t plummet to the ground. More importantly though is that when you are on rope there are occasions when you need to do ‘technical manoeuvres” on rope (see the menu on ‘technical SRT’). When doing these technical manoeuvres having a stop that you can let go of without having to do a lock off is handy. In simple terms, it is comforting and convenient that if you need to you can just forget your descender.
All sorts of things can go temporarily wrong with SRT, almost all of which are fixable given you stay calm and think logically about how to rectify the situation, but a stopping descender takes one worry out of the equation. The proper etiquette is that you still do a hard lock off on a stop, but in reality if you don’t have time to do that, or you forget, it won’t matter.
The next most popular descender is a ‘rack’ (known in certain places as a ‘rappel rack’). Racks are particularly popular in North America. They do not have an auto break, so if you let go of the rope in your right hand you will descend very quickly (although not as quickly as a free fall). But they do have some major advantages.
Firstly, you can pretty much go as fast as you want. Stop descenders get very hot if you abseil quickly, and can burn through rope if you go to fast, but racks have better heat dissipation. Also, the ride on a rack is smooth, not jerky like on a stop, particularly on stiff or thick rope. And thirdly on a rack you have more control on the amount of friction being used. So, if you are a beginner or a bit nervous you can add friction, or if you want to go really quick down the pitch and are an experienced caver you can have very little friction.
Ascending – a little more tricky
This is where it gets a little more complex, and it’s hard to know how or where to start the explanation. The common misconception is that it is easy to just climb up a rope arm over arm. I guarantee you that you wouldn’t even make it up 10 metres doing this, and would slowly weaken until you were not able to climb any further.
So – you need a way to ascend on a single rope, under your own power, with the facility to take a break when tired, the ability to have two attachments to the rope for safety, and the reliability not to fail in any conditions (i.e. even when wet or muddy).
The prusik knot
Many years ago, the prusik knot was invented. This was a knot that when tied around a rope would grip it, so that you could slide the knot up but not down. Also known as a prusik loop. Cavers quickly realised that this was far better for ascending deep pitches than ladders. It was not long before the first mechanical versions of ascenders were invented. In fact, there is evidence to suggest that the first mechanical ascenders were used in the mid 1930’s. But by the 1970’s they had become commonplace. These ascenders, like the knot I described, allow the device to slide up but not down.
What all SRT ascending techniques have in common is they use these ascending devices. However, there are quite a few variations on the details. Some attach ascenders to the feet. Some have three ascenders working instead of 2. But the most common in Victoria, is the frog system.
The Frog Technique – The world’s most commonly used ascending method.
Put simply, the frog system relies on two ascenders. One is held in your hand (usually connected to your harness/central maillon). This hand ascender has attached to it a length of rope or tape connected to a loop that you step into. The other ascender is attached to your chest. The concept is simple –
1) Raise your hand with the ascender. As you do this, the foot loop a metre or so down will also ascend.
2) You stand into the foot loop which ideally means your leg goes from a 90 degree bend to being straight, giving you about a foot of lift.
3) As you stand using the foot loop, the rope runs through your chest ascender on its own.
4) You can then relax, and as you do so your weight Is taken by the chest ascender, and the foot loops and hand ascender whilst still being attached to the rope, are not taking any of your weight.
5) Repeat the above process – STAND, RAISE, SIT, STAND, RAISE, SIT, STAND, RAISE, SIT. Etc. until you are at the top of the pitch.
There are many subtle variations on this technique, but it’s all based on the same principles of ‘biting’ the rope to slide up but not down.
So that is how to ascend and descend a rope, with no help from anyone else, safely, efficiently and quickly. The nice thing about SRT is that you can take your time, and when tired you can just let go of the rope and float around for a bit until you get your breath and then keep going. The other crucial advantage of this is that it is almost all leg power, not arms, so you have a lot more stamina.
This process of ascending is called ‘Prusiking’. It is FAR easier and more efficient than laddering. But there is one major problem: Rub Points! See the next menu item to find out what rub points are all about.
There is more detail on the ‘Rub Points’ page. But I will say now that once you’ve done enough horizontal caving and you are ready to get vertical, take it seriously. You need your gear to be set up for your height, arm and leg length, your waste measurements, and measurements of your upper thighs. The length of your leg loop will also vary, and I’d recommend getting an easily adjustable leg loop so that you can get more height if you need it.
Ideally, you need to be intimately familiar with your SRT. So much so you can put it on and be ready to go within a minute or two. And even more so, that you can do it in the dark, or wet, or in cramped conditions. You have to remember you have other cavers waiting for you at the bottom and/or top, and they may be wet or cold. Having said that, fast is NOT necessarily going nuts and wearing yourself out in 10 seconds – fast is having good steady smooth and efficient technique.
The efficiency of you ascending means how much rope you pass through you with each ‘step’ up you do on the frog system. If you are a 6-foot-tall male, getting as much as 2 feet of ascension per prussik is pretty good. Shorter people will get less. And if your gear is not configured correctly you will lose efficiency.
So, know your gear. Play with it. Put it on and off. When you’re caving with it give it a thorough inspection before every trip. (And also check your ropes regularly too!).
Falling on a rope
A fall on rope in any situation is more serious the less rope is above you, simply because there is less stretch to absorb the fall. We use static ropes in caving, which are ropes with less stretch, as falling onto them is a very rare event (I’ve only seen it happen a couple of times). The less stretch is because that when the pitch is any longer than about 15-20 metres you start to get bounce in the rope. On a long pitch of 50m or more you are bobbing all over the place, and potentially sawing gradually through a rub somewhere. Climbers use dynamic rope that has lots of stretch as they often take falls. This is another reason we use figure 8 or figure 9 knots as they absorb some of the potential fall. If a rope takes a fall, it should ideally be thrown out. Also beware of any SRT gear that is dropped onto rock or solid surface. If it has fallen more than a metre or so, technically it should also be thrown out as it can develop hairline fractures and weaknesses. This mainly refers to carabiners and maillons. Your whole SRT kit should be replaced regularly, I’d say every 5 years with moderate use.
A practice I have adopted is that now every time I take off my gear I dis-assemble all the parts. And when I put it back on I put all the parts back on one by one. This means I know for a fact that everything is done up and in its right place and I notice any problems. Most people leave the kit all done up so all they do is quickly slip it on and do up the central maillon. This is fine, although it’s annoying when it gets tangled, which happens easily when its dark, you are wet and tired etc. As long as you are quick enough in assembling it all every pitch you do then its fine.
I have had a million different SRT rigs shown to me and justified as to why they are the safest, easiest, fastest, etc. To be honest, I think that ultimately it is how you use the rig which determines the safety and efficiency. Particularly your two safety ropes (cow’s tails). These things are your life! Alpine cavers (Europe) only use two, to save weight, but in Australia we don’t have any caves (Even in Tasmania) where we are trying to save weight that seriously, so I choose to use three.
The bible of SRT – ‘Vertical’ by Al Warild
If I haven’t already mentioned it somewhere in this site, when you feel ready to start SRT, order a copy of ‘Vertical’ by Al Warild. Or it is also viewable for free at http://www.cavediggers.com. He is Australia’s ‘best’ caver (if you judge best by he’s bottomed the world’s deepest cave, and has written a book, and has been on some insane expedition caving). ‘Vertical’ is the bible of SRT and it is not overly technical, easy to read, cheap, and he is an Aussie! There is nothing in Vertical that is missing. Whilst real training on a cliff with an instructor is probably more useful, reading the book will help your skills immensely.
In terms of Victoria, if you include the caves on public caving reserves, and the caves on private property that we have access to, and the permit caves on Parks land (so we are talking probably 200 caves or more) I’d say more than 50% have a pitch inside that needs SRT. Sometimes it’s at the entrance, sometimes deep inside, sometimes massive and sometimes very snug. But there’s lots of them. In fact, in Buchan, there are only about 10 easily accessible and extensive public caves where NO gear is needed at all. If you count ladder caves as those as needing gear then it’s more like 75% needing gear of some kind.
To be a caver in Buchan, you will run out of caves quickly unless you learn SRT.
So, to be a caver in Victoria you do really need vertical skills eventually. Quite a lot can be done on ladders if you don’t mind them, but most cavers don’t like them at all, and when you first do one you’ll understand why. They take more strength to ascend, they flail and wobble around, resting is (possible) but harder than on SRT, and when they are against a wall which is more than half the time it’s a pain to get your hands and feet into the rungs. As I’ve said in the laddering section, they are all about technique. The VLCT Caving Club are well known for using ladders a lot and are happy having developed excellent laddering technique and use of belays, but most of the active cavers will use SRT on anything over 10 metres. The only other advantage, again as I’ve stated, is that rub points aren’t an issue on a metal ladder. I caved for about a year before starting SRT. In Buchan learning SRT opens up dozens and dozens more caves for you to explore.