Vertical caving terminology and methods > Prusiking systems, prusiking methods > Step or rope walking systems, sit on the heels systems
A step system for prusiking which is based on the Gérard Alpine technique, but which lies half way between the Texas system and Mitchell system, and could easily be created from either. The legs perform a lot of the work. The arms are each used for moving an ascender upwards, and for balance when standing. It allows a variety of different motions depending on the situation, such as sit-stand like the Texas system by ignoring the footloop of the top jammer, stepping along a sloping pitch, or more commonly a sit on the heels motion. Unlike most other step systems, the sit on heels motion requires an unusual extra action to maintain balance, where immediately after standing, the dominant foot is swung out to the front while lifting its ascender, then the other knee is lifted and bent so that it tucks underneath the body while lifting its ascender, then the dominant knee is bent to give a position of sitting on your heels, followed by standing upright again. So it becomes kick, step, squat, stand. Originally intended to be used for prusik loops.
Very similar to the Texas system in terms of convenience when passing deviations, but actually slightly easier for rebelays, because the top jammer has a footloop to stand in if needed. It can be relatively easy to use for passing a knot while abseiling if the footloops are long enough, and is always relatively easy when prusiking. Reverse prusiking is relatively easy compared with some other techniques. If this is being used as a sit on the heels system, bottom weighting is done by manually pulling the rope below the lower jammer. If this is being used as a step system, it is particularly awkward for bottom weighting, since the feet move separately and cannot trap the rope, and the hands are also occupied and cannot pull the rope through the lower jammer. The only remaining option is to push the cam open of the lower jammer, but this really is very fiddly. Mid-rope changeovers are relatively easy. Normally better than the Texas system in terms of energy transfer efficiency, but this depends on how it has been configured and is being used. It is more stressful than most other step systems, and more stressful than the frog system. Taking a rest in the original configuration is very uncomfortable, as it means having to hang from the chest harness. With the Kaczmarek system or spiderweb system, taking a rest requires one leg to be bent or taken out of its footloop, so that the top jammer can be lifted. Very awkward with a nearly-vertical pitch or narrow pitch, but can work on free-hangs or very significantly sloping pitches.
Uses a top jammer with a footloop and a lower jammer with a footloop, with one foot in each footloop. The dominant foot uses the top jammer's footloop. Both ascenders have safety cords. Originally only the top jammer had a safety cord, but this would almost certainly result in a fall if the top jammer disconnects, so a safety cord for the lower jammer is not optional. This is essentially the same as the Mitchell system without its chest roller, or the Texas system with a second footloop.
There is a lot of variety in how the top jammer's safety cord can be set up, and each version might give different performance in different situations. The top jammer's safety cord can be connected only to a load bearing chest harness, which is the original configuration. The top jammer's safety cord can be connected only to the sit harness, which will result in very poor balance, and will only allow the same motion as the Texas system (and is therefore not worth using, since it defeats the purpose of having two footloops). The top jammer's safety cord can be connected to the sit harness and passed through a carabiner that is clipped to the chest harness to try to pull the body a little closer to the rope. There can be separate safety cords from both the chest harness and top harness, each connecting to the top jammer. Some proponents of the system preferred to have the safety cord relatively short, connected part way down the top jammer's footloop. When using prusik loop, this was often done using a friction hitch on the safety cord to connect to the footloop, allowing the system to be converted to the Gérard Alpine technique if needed. When it has safety cords from both the chest harness and from the sit harness, each connected directly to the footloop cord, it was known as the Kaczmarek system, or if those two safety cords connect together before connecting part way down the top jammer's footloop, it is called the spiderweb system, but these are basically the same thing.
The length of the footloops can be set according to the desires of the caver. Some preferred to have short footloops of waist height for the top jammer, and just under waist height for the lower jammer, particularly if using the sit on the heels motion. Some preferred to have the top jammer's footloop long enough to reach the face for the top jammer, and just under waist height for the lower jammer. This is normally preferred when making a convertable system such as the three phase system, or when preferring a stepping motion. Whichever way it is used, the lengths of the footloops and safety cord are absolutely critical. Even a slight error, and it ends up as a malfunctioning Texas system. This makes it very frustrating to configure, and that is presumably why so many configurations use friction hitches on tethers leading to more friction hitches, so that the length of each part can be adjusted in use, to correct the errors in the lengths.
Even with the lengths set perfectly, the Plummer system still requires a lot of effort to use it as a proper step system, as the arms have to constantly fight to keep you upright, while moving their respective ascenders. This results in a very uneven motion, always trying to keep the top jammer lifted for as long as possible, since that makes it easier to briefly relax the arms. So even though it is technically a hybrid of the sit-stand Texas system and a step system, it really can only be conveniently used as a sit-stand or sit on the heels system. Where it is really useful is for walking up a significantly sloping pitch, where the stepping motion can be independent of the safety cord.
The three phase system can operate in three modes (described in that section). When its quick attachment safety is connected to the top jammer's footloop, it acts as a safety cord connected to the top jammer's footloop, and turns it into the Plummer system. In that mode, it was intended to be used for walking up significantly sloping pitches.
American caver Bill Plummer claims that American caver Huntley Ingalls created the idea behind the Plummer system "years ago" before 1960, probably in 1957, though Huntley Ingalls did not remember if he did. Either way, it was an adaptation of the Gérard Alpine technique, removing the chest prusik loop, and connecting it to the top prusik loop. Bill Plummer wrote about it from 1960 to 1966, and refined it, offering different configurations and footloop lengths, some feeling more like the Texas system, and some feeling more like a sit on the heels system. American cavers Dick Boyd, Carl Poster and Bob Olmstead were among the first to use this system with mechanical ascenders in 1965, while creating the Wisconsin system, but this approach was dismissed. For the next few years, the system was hardly ever used with mechanical ascenders, and subsequent development happened with prusik loops. American caver William Franklin "Vertical Bill" Cuddington was frequently seen using a variety of chained cords connected to each other via Prusik knots instead of just being tied to each other. While this looks really chaotic, it always seems to end up being a Plummer system, often the Kaczmarek system variation of it, which he was first recorded as using on an ascent of a mountain in 1966. In his configuration, the safety cord from the sit harness acts as a top prusik loop, a footloop connects part way up it, a safety cord connects the chest harness to near the top of sit harness safety cord. American Mike Kaczmarek separately recreated the Kaczmarek system variation in 1967. In his configuration, a prusik loop acting as a top jammer has a footloop, a safety cord connects the chest harness to the footloop cord, and a separate safety cord connects the sit harness to the footloop cord a little lower down. The result of these two configurations is exactly the same, but one is much more easy to understand, and the other has a direct connection between the sit harness and the top prusik loop, without relying on intermediate prusik knots. Robert "Bob" Thrun describes another recreation of the Kaczmarek system as method 17 in Prusiking, 1973, but neither the recreation date nor its creator are known. The origins of the Spiderweb system are not known, but it was before 1973. William Franklin "Vertical Bill" Cuddington developed the three phase system variation some time between 1969 and 1974, popularising the use of mechanical ascenders with the Plummer system.
This history section only covers the Plummer system. This article also has a detailed history of many of the other devices and techniques that are used for vertical caving.
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