Vertical caving terminology and methods > Prusiking systems, prusiking methods > Sit-stand systems
A slight variation of the frog system, that can be used to lift heavier loads, which is useful when hauling large amounts of equipment, or during improvised rescues, or when muscles are tired. Cannot be easily used for prusik loops, unless the top prusik loop is short enough to fit a pulley between it and the D-ring.
Passing rebelays, deviations, reverse prusiking, bottom weighting, and most other things are identical to the frog system. Makes mid-rope changeovers easier for some cavers, which also means passing a knot can be easier too. The main benefit is a double or triple power advantage. However, it does so at the expense of preventing convenient use of a foot jammer (since that cannot have the power enhancement). It also reduces the amount moved per standing cycle. This can make some improvised rescue techniques more awkward in cases where a larger movement might be needed to lift a casualty off their equipment.
For the Mao variation of the Italian technique, the footloop is connected to the top of the chest jammer or D-ring, then via a pulley which is clipped to the bottom of the top jammer, and then down to the feet as normal. This halves the energy expediture during each sit-stand cycle, but also halves the height gained. Another variation is the Ded-Mao-pompe, where the footloop's cord starts at the top jammer, passes through a pulley at the footloop, then back up through a pulley at the top jammer, then down to where it is clipped to the top of the chest jammer. This now gives triple the power, but a third of the height gain. The sit harness plays an essential role both as a main support and for safety. The chest harness is only used for efficiency.
This prusiking system was developed in Italy in 1974, but its creator is not known. The Ded-Mao-pompe variation was first described by French cavers Bruno Dressler and Pierre Minvielle in La Spéléo in 1979. Petzl produced the first dedicated top jammer for this system in 1991, and released it in 1993.
This history section only covers the Italian technique. 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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