Originally Posted by atavist
Unfortunately I have no idea what "Rappelling on a figure-8" means... I did some self-belaying rappelling, and fast-roping while in the Marines and a lot of alpine style hiking/climbing but have never done any technical/vertical climbing (other than masts)... Got any web references for these techniques, they sound much handier than my current methods... I usually just climb the rigging and drag a rolling hitch behind me on an anchored halyard and then switch to a prusik loop once where I want to be.
Typically use a webbing seat harness (can be made of rope, of course) to attach the Figure 8 to. Here's an example of the device. Link
Here's a page of racks
if you haven't seen them. Safer than a Figure 8 if you're rappelling more than 200 feet as you can add bars or not depending on the friction of the length of rope below you.
If you get a copy of Brion Toss's Riggers' Apprentice
, a lot of good information is in there about climbing your rig safely. I imagine you could find something online about vertical caving or spelunking that might show the techniques I'm talking about. These days, it does seem that folks use ascenders rather than knots. I don't consider using a Prussik knot as safe as the one I described. Since our knot isn't in any books, I'll see if I can't take a couple pics of it being tied and post them for you.
**edited to add: on page 260 of the Riggers' Apprentice
there is an illustration Figure 7-12 of someone using something called a "ropewalker" that is essentially the method I describe if one has Jumars. However--this is a BIG however--the figure shows an UNSAFE climbing technique in that the person is only tied in to the rope with the belt harness. A person can slip out of a seat harness and I was taught to always climb with a chest harness in place and at a minimum have a carabiner attached to the chest harness and around the rope OR better yet have a knot or ascender in place at the chest harness.
There is a set of pictures here at this link
that can help you understand using the system I'm talking about. This fellow has made what he calls a ropewalker from three Gibbs ascenders. I wouldn't use such ascenders, they are not as easy to use as other higher quality ascenders and further, knots take up much less space! The climbing technique the fellow is using (with chest harness) is proper. I note there's another page where a fellow is shown not using a chest harness--unsafe.