The LSD Lower
When belaying a follower in guide mode, the belay device will be clipped to the anchor, with a locking carabiner holding the rope in place. ( For a tutorial, see tinyurl.com/kvprbgd.) The LSD lower uses an additional biner on the anchor to allow for lowering and to defeat the autolocking function of guide mode.
BACK UP THE SYSTEM
First, build a back-up. This is mandatory for any complex technique or when system failure would be catastrophic. Tie an overhand-on-a-bight in the brake strand 4 to 5 feet behind the device and then clip this “catastrophe knot” to your belay loop with a locking carabiner.
Before lowering, build an autoblock with a Prusik on the brake strand above the catastrophe knot. Clip it to your belay loop with a locker. This functions as your “third hand,” freeing up your mitts for the LSD lower. Cinch the autoblock up the rope so there’s an inch or two of slack. Now, there is no way to drop the second.
SET THE LSD
To begin your lower, hang a locking carabiner off the anchor, in front of the device. Ask the climber to unweight the rope. As he does so, clip his rope strand through the locker and lock it, and then he can sit back. At this point you’ve defeated the device and a bit of rope will slip through—your autoblock should engage and you’re now in the LSD lower. (If the autoblock does not engage, the catastrophe knot will save the day.)
Once the autoblock is holding, undo the catastrophe knot and lower your climber using the Prusik. When he’s ready to climb again, he can unweight the rope momentarily, at which point you pop his strand out of the locking carabiner in front of the device. Bam—he’s back in guide mode. (Consider rebuilding your catastrophe knot during the transition back to belayed climbing.) Once he’s climbing again, remove your third-hand backup and belay as before.
Clip third hand to belay loop above catastrophe knot (not shown) Carabiner redirect allows you to use device to lower