Um, well, maybe not. Rich is very anti-autobloc, and those knot-tying sites do not discuss the subtleties such as:
1. Absolutely, not for use in waterfalls or moving water. Also, it will not "always" grab - if you flip upside down, it will reach to your rappel device and not grip. It is not a 100% foolproof technique (but it is pretty good).
2. A good tool to know, and use selectively. In order to continue "knowing" it, you will have to practice it.
3. The AutoBloc knot is very much preferred. Other knots (Kleimheist, prusik) once loaded are very, very difficult to release.
4. The SETUP is very important. The LENGTH is very important. The Autobloc must be short enough to NOT reach up to your rappel device. If it hits your rappel device, the device will "tend" the autobloc, or will get stuck in the rappel device.
5. The wraps will vary with your rope parameters. Each change in parameters will change how it performs. Size of rope, number of ropes, the wetness of the rope, the roughness of the rope, etc. Everything makes a difference.
6. It works well when the ropes don't change. Guiding, we always use canyon pro, and our autoblocs are a pretied length. We use three wraps on a single strand, and four wraps on a double strand. On a regular trip, using several different ropes, it will work on some, and not on others.
7. The SETUP: clip a carabiner to your leg loop, dominant side. clip the loop into the carabiner. Wrap the autobloc around the rope three or four times, and clip the end bight back into the same carabiner.
8. Is it right? - the length needs to be such that the knot grabs the rope if you let go of everything. Add more wraps? Can. It needs to be loose enough to not grab so much as to be difficult. It needs to be short enough that it does not reach to the belay device.
9. Modify the Setup: for many people, it will work better to extend your belay device a few inches, to keep it further from the autobloc. This is critical for children, youths and small women (small canyoneers). Usually helpful for men with a substantial pony keg (ie, table muscles, aka fat gut).
10. While rappeling: for the autobloc to grab, it must move up the rope to an upper position. In order to "go", the autobloc must be held down a few inches so that it does not grab. It is better to hold it in a fixed position and let the rope slide through it; than to let it grab, then release it, grab/release, grab/release. Each time it grabs, it tends to grab tighter, and be harder to release. The "other hand" is the brake hand, controlling the flow of the rope, and can be either above or below the autobloc. I often start using my right hand on the autobloc, and then switch to the right hand below and the left hand on the autobloc once I get going.
11. Some other tricks: CAN squeeze the rope through the autobloc, to gain a little more friction. CAN angle the rope through the autoblock to vary the amount of friction.
12. Autoblocs can be made from 6mm cord, tied in a loop. Tie the ends using a double fishermans with very short tails, tighten well, then toss in the laundry for a couple cycles. They tend to be slick and not very grabby to start. Once they fuzz up they work well. After repeated dunkings and dryings, they get shorter, which makes them grabbier. For 6mm cord, a good cut length is: (Tom to go find and fill in later).
13. At ZAC, we are now using sewn ones made by Sterling called Hollowblocs. I plan on carrying these in my store in the spring.
I'll try to write this up with pictures ... (don't hold your breath).
Tom