hoehlenforscher said:
The diagram shows the use of a foot jammer in combination with the (uk) standard chest and handled jammer in order to make a simple rope walking rig. i have seen this setup demonstrated while on the continent, its advantage supposedly is that one can switch to a frog rig relatively easily if needed. However, due to it all being a bit fiddly on our (european) genarally shorter pitches with multiple change overs it has never really caught on. The foot jammer itself doesnt really stay on the boot very well we found and you have to take it off between pitches or you can trip up on it or get it full of shite.
A common misconception is that a foot jammer is only useful for rope walking on long free hanging pitches and looses its usefulness when there are more rebelays and short sections. In fact the situation is quite the reverse. The foot jammer is extremely useful in more mixed territory and is often useful when "frogging" rather than rope walking. It is particularly useful in the following situations:
a) At the bottom of pitches or just above rebelays. Because the foot jammer slides without much friction, it means that once you are literally about 1 metre off the floor you don't have to worry about the rope pulling through you chest jammer. No more dropping back 10cm at every cycle, desperately trying to pinch the rope between your toes.
b) Ramps. Sloping pitches are a real pain with a frog rig, because you tend to lose balance and swing around. The only real way to solve this with a normal frog rig is to prussik with one leg, using the other for balance. With a foot jammer, the two feet can work independently. If you slacken off your chest harness a bit and keep your body vertical, you will find that you can walk up sloping pitches as easily as walking up stairs.
c) Tight pitchheads. With a normal frog rig, once your top jammer hits the belay, that's as far as you are going to get on the rope. From that point on it's brute force and a lot of struggle. With a foot jammer you can gain that extra metre which makes all the difference. A classic example of this is the oil drum entrance to Stream Passage Pot. I have sat at the bottom there listening to each person going out cursing and struggling. When it was my turn I simply "levitated" out using the foot jammer until I was sitting on the top, much to the disgust of my companions, who threatened to confiscate my foot jammer and make me do it again "properly".
d) Even in free hanging pitches, the foot jammer increases efficiency when frogging. It increases tension in the rope, keeping your chest jammer properly in line, reducing friction and backlash and helpinging you to put the effort in exactly the right direction. It might only be a 10% saving in effort, but even that justifies the weight and extra complication.
My foot jammer is definitely part of my standard equipment. On rare occasions when I cave without it (if I forget it, or have lent it to someone curious to see whether it is worthwhile) I realise just how much it has changed the way I cave. It feels like a definite step back into the "bad old days".
Funnily enough, the first serious trips I did with it were actually out in Austria. After prussiking 330m up 12 quite technical pitches in one hour and and a quarter I was impressed!
Mark