using an atc-guide when the anchor is far away

I have a question about using an atc-guide or other auto-blocking belay device when the anchor is "far away". I have the following scenario in mind: I get to the top of a formation and the only suitable anchor might be a tree that's a ways back from the edge; let's say 20 feet. (The location I have in mind is the top of the Wind Tower; the rock is generally crap at the top but there's a solid tree a ways back that I use for an anchor.) I like to be in visual contact with my second so I'll use the tree for an anchor and then extend out to the edge using a couple of different methods. It depends on the situation, but I generally like to use my atc-guide in auto-block mode when bringing up the second, especially if she might be a little shaky following the pitch or I want to coach her through a section.

The ideal situation is to attach the atc-guide to the anchor for auto-block mode. Since the anchor is relatively far away from where I'm standing that would seem to present a problem particularly if I need to give a little slack. What do I attach it to? I can't belay off my harness and use auto-block mode. At least I assume I can't.

Is there any way to satisfy both of my constraints: use the atc-guide in autoblock mode and be far away from the anchor? Or do I need to sacrifice one of the conditions (I could be close to the anchor but out of visual contact or I could be in visual contact but not use the device in auto-block mode)? I have an idea for a solution but the more I think about it the more sketchy it sounds so I thought I'd see what other people think.

How are you extending the anchor? If you are using the climbing rope, you must be very wary of the stretch of the rope allowing you to be pulled over the edge or losing control of the belay. If you have some sort of static setup to extend the anchor you must also be mindful of the direction of pull; you could still be pulled over the edge.

Autoblock belaying off your harness is not recommended. Almost any method of extending the anchor is going to put some play in the system, especially if you add your harness and body into the mix. It would be very difficult to unload the autoblock should a fall occur.

It is not a good idea to have the autoblock at the anchor since it is too far away to unload.

How about using the tree as a directional anchor and belaying from the edge with an extended "personal" anchor? This has some advantages and disadvantages depending on terrain and available rope length.

What about doing this?

Tie a bight in the extender an arm's length from the ATC. Clip a biner into the bight and pass the release sling through the biner.

I just tie a bight in the rope and use that. The trick is to get your anchor tie in length (the other side of the rope) to work in an ideal position.

It's hard to explain without a visual. I keep the belay device near me even though the anchor is at some distance; with both myself & the belay device on different strands in relation to the main anchor point.

You guys are making this way too dificult. All you need to do is clove hitch a locker into the rope coming from the anchor to you about an arms length away from you. Attach the ATC to this locker and you have your setup(just make sure you are between the anchor and the follower).

If I am moble at the belay ( have maybe 5-10 feet of rope and am on a ledge) I will take the ATC directly to the tree. If I have to lower then I just get up and walk over to the tree and as you should have some friction where the followers rope goes over the edge it will not be a problem to release the ATC and give slack.

Kev - man, I don't feel good about cloving that setup. I feel better with them on an 8 bight on the main line; the're already fixed if I have to go down and assist. If I need to lower I can use my tie-in strand for the pulley (should work with up-haul also) -- this would be using the opposing anchor strand, which sets up a counter; I keep it all near me & can keep the lower from the rock edge with my foot if need be & watch them also.

Just extend a length of rope from the anchor to you and use a directional figure eight, clove hitch or whatever knot you are comfortable with. Also there is a small hole at the front of the ATC Guide that you can girth hitch a sling to (new 10mm dynex BD or the 8mm Mammut work well) and can release the device when you need to lower or provide slack to your second.

I still like using a directional from the anchor; you are basically top-roping the second, allowing for easy lower or escape. However, I will admit that this is not good if the edge is sharp or there is a lot of loose rock.

I like Mark's suggestion best, put a bight in the main cord at the anchor and now you have 2 redundant strands, one for your anchor at the edge and one for your auto block set up. Very easy to escape and lower from, as long as you have your release system set up.