When choking my line on a spar, I use a keyhole type Krab. If the spar splits, the krab pushes down against the hitch, pulling enough slack as necessary.
With a lanyard its a little more tricky. By clipping into the centre 'D's, the climber won't get caught in the bight, but the lanyard could still break. Also, it can put the climber too far back from the stem to position correctly.
I run my lanyard from hip to hip. To protect from splitting, I place a krab and micro pulley between each leg of the lanyard - the pulley goes just above the the hitch, and the krab attached to the pulley clips over the lanyard on the opposite side. A sling can be placed between the two for wider spars. A split will cause the pulley to push down on the hitch. I undo the stopper knot in the end if I half expect this on a large spar - that way I can come off the lanyard and fall into the choked lifeline that was set up as previously stated. When I figure out how to post photos I'll do it!
As for knockin out 12' sections on a rope, thats some hellish loading on your rope. I doubt if the value of the timber is worth that, let alone your life.
I would never tie into a pull line Brian - the pull line gets one hell of a hammering if the section piles it into the deck!
When descending to the next section, I'll unclip the lanyard and descend on the muenter hitch backed up with the Distel. But not before clipping my friction saver or footlock prusik into the keyhole biner used to choke the lifeline. This plenty long enough for repeat cutting of 4 to 6' sections. Get to to the next spot, lanyard in and repeat. I'll use an alpine butterfly with a long tail to reach the ground when I'm ready to fell the trunk.
Descending on the choked lifeline helps a great deal when over coming bends in the trunk on the descent - sometimes its impossible to get a gaff in that won't gaff out when you commit to it.
[ October 03, 2002: Message edited by: MrPez ]