I want to make a ropewalker; but here in Europe, nobody uses them. Therefore I have no experience of "proper" ropewalkers, and my only knowledge is some basic theory from books. This is where you come in!
But it's more complicated than that, because I'm not looking for a standard American-style ropewalker -- such as a double-bungee system. I want to take my Frog setup, and tweak it to allow ropewalking as well. I believe this can be categorised as a single-bungee ropewalker that converts to frog. So far, this is what I have:
- Standard frog setup, plus Pantin, using an MTDE Garma chest harness
- A bungee cord attaches to the back of the chest harness. The other end of the bungee has an accessory carabiner
- A loop knot is tied about half-way along my footloop, allowing me to shorten the footloop
This is essentially the same as the "stair climbing" setup described in Alpine Caving Techniques. Converting from frogging to ropewalking is quick and can be done mid-pitch:
- Shorten footloop by clipping intermediate loop into the krab on my hand jammer
- Remove hand jammer from rope, and reattach below Croll
- Clip bungee cord to hand jammer
The "hand" jammer thus becomes a "knee" jammer, which is pulled upwards by the bungee. You hold the rope with your hands to keep yourself upright and balanced. I have tested this system on expeditions and it can be very fast -- potentially a lot faster than frogging, or even "frog walking".
There is one major downside: because the system lacks a chest roller and relies on the arms for stability, it can get very tiring. There is too much arm work for me to use it extensively in deep caves. Therefore I want to try incorporating a chest roller.
In general, European cavers know bugger all about chest rollers. It is a foreign piece of equipment to us. Here is what I currently think; if I'm getting this stuff wrong, please correct me:
- Rigid plates are preferred to straps, because a rigid plate does not bend, and therefore holds you closer to the rope.
- A high attachment point works better, because it keeps you more upright. Typically you want it to sit somewhere between the nipple line and collar bone.
- Products such as the PMI roller plate are popular. These plates are designed to attach to specific types of chest harness.
The PMI roller plate looks great, but it is not suitable for my application. It is too heavy, too bulky, and will not attach to my chest harness.
I already have a Simmons field roller, which is light and compact. I just need a way to mount it effectively on my chest harness. I don't need anything strong (it's not life-support). I want something light and compact; ideally I would like something that can be folded for storage, and easily removed or added.
The MTDE Garma is a "solid" chest harness. It has two straps that come over the shoulders, with buckles at about the right height for a chest roller (see this picture -- on me, the buckles come down lower). I'm planning to use these, by sliding a compact roller plate between the buckle and the strap (where it doubles back). I then need something to secure the plate at each end -- some kind of spring clip that blocks it from sliding back through, perhaps. If the roller plate was hinged, it could be neatly folded away when not in use.
The trouble is, I have no idea where to look for such a thing, and I don't have machining skills for making one. I feel it must be possible to assemble this from common parts available at hardware / DIY stores -- but I don't know where to start! Where would I find a bracket / plate that could fit a Simmons roller, ideally is hinged for folding, and could be fitted with some kind of expanding spring clips at the ends?
The bracket / plate would not necessarily have to fit through the slit on the Simmons housing. I could always thread the Simmons with webbing, and then screw the webbing to the plate.
Alternatively, what other solutions might work?