wellyjen
Well-known member
It really would. Unfortunately, the data doesn't exist. It all comes from existing topos, drawn up over several decades and rope lengths used between anchors wasn't something that was recorded. The rope lengths given in topos are often arbitrary on multi pitch shafts and as likely to be where the person on the topo drawing trip happened to pick the next rope out of the tackle bag at a rebelay as any other consideration. Given that limitation, Ari's tool is rather clever. Sometimes topos will include pitch lengths between rebelays and with suitable allowances for rope loops, knots, Y hangs and so on, then you can estimate what length will likely work to an intermediate anchor from the topo.Re. Passing knots - plenty of times you can (with planning, rather than finding yourself accidentally 10m off the deck) use the additional rope for the traverse so no knot pass is needed. Max length of rope between two anchors would be a useful variable to know
As for passing knots mid pitch, I'll only rig like that if it is absolutely required and I know every one on the trip can cope. If some one has only just learnt SRT and has done a couple of practice knot passes in a barn, there is a good chance they'll struggle with one in a cave and I'll change the cave, rather than include a knot pass. With a bit more general SRT experience, a first time underground knot pass is less likely to turn in to an epic.