Tuesday, 28 January 2014

Working a Spar SRT

I dismantled a large oak earlier this week, the crown came out easily enough and we were down to the stem by lunch time(ish)

Call me a cheat for using ladders but It's still the quickest way into a crown!
The stem was obviously slightly more time consuming, especially as it was up to a metre in diameter in places and due to a fragile patio underneath everything had to be lowered. Now I quite enjoy blocking down big lumps of wood but they can be pretty time consuming to set up, which is why I frequently work them SRT.

I simply choke my line at the top of the last cut, descend to where I want to cut next (with rope wrench attached) I have the pulley block, dead eye and rigging line clipped into my anchor ring, so they are out of the way and not hanging off my hips, I am then easily able to make the face cut without any danger of cutting anything. 
The stem after 3 or 4 large lumps had been rigged down, you can see the largest still at the base of the tree, to big to be moved we had to cut it up where it sat.

Once I've made the face cut, the pulley is attached as close to the face cut as is practical. The rigging line and pull line (if applicable) are next to be attached before I strop in, move my SRT anchor to just above the pulley, make my cut and hold on! Then its a case of un-tieing the dead eye, clipping it to my anchor ring (pulley/rigging line still in place) descend and get ready to start all over again!

When it comes to either descending to a point where I can't reach my anchor to retie it (or coming down at the end of the day) its a good idea to make the anchor retrievable, in which case I use an Alpine Butterfly

First enough rope is pulled round the stem to reach the next point/ground, then I tie the alpine butterfly into this long end, then simply clip a karabina through the loop and onto the other part of the rope (closest to harness/hitch) making sure the gate is facing up, this is then synched up tight to the stem.

Now I wouldn't recommend this as a permanent anchor to work an entire tree, but for working on a large diameter spar like this I think its fine; its always in sight so you can see its not cross loaded or coming undone, and the stem is large enough that the krab is being weighted along its correct axis.  

Coming down at the end of the first day

Retrieving the anchor 

Then when it comes to retrieving the anchor you just pull down on the knot side of the rope until it gets to you, unclip, untie the butterfly and pull the rope down. 

No comments:

Post a Comment