Moss figured out a nice SRT pull down system, where a Prusik loop rides to the top of the limb. The throwline attaches and pulls on the Prusik loop. That in turn pulls the cinched delta down the the climb rope. The benefit is ease of pull down. I know this works. I've had to reclimb a 120' SRT because the mechanics aren't there for the throwline to pull down the delta directly.

What if you didn't have a Prusik loop available? I experimented with a conventional bowline. A butterfly (alpine) knot was placed on the bowline loop. A delta was attached to the butterfly loop. The delta cinched the climbing rope to a limb. This seems to emulate what Moss created. I like the idea of two knots in series: creates a back-up.
[img]<img%20src="http://lh5.ggpht.com/__xEse-DqPgo/TLJQLZaFgLI/AAAAAAAADPU/9NsuSRWJ0y4/s800/Pull%20down%20SRT%20Cinch.jpg"%20height="800"%20width="657"%20/>[/img]

Ah, interesting knot within a knot. You might have inspired me for another idea I'm working on.

Why even use the butterfly knot though? Yesterday I retrieved a tyrolean traverse using the unloaded strand of a bowline on a bight, it worked fine but there was some resistance since the knot was not inline. (as is with the bowline).

I usually just tie the throwline above the loop knot a clove or constrictor hitch works fine but being particular and habitual I use an Ossel Knot. It slides up and down the rope like a prusik does (and more easily than the clove and clove variants) but bites when loaded. A slipped version is especially keen.

I like the Ossel, besides the functionality it practically ties itself, it makes sense visually as you tie it in the video.
-Anderw

Here's the thought progression on this configuration:
Can't use a standard bowline as a termination knot; it can roll into a slip knot
Using a Yosemite tie-off on the bowline sends the end the wrong direction
Butterfly is my most robust attachment knot, yet it can't be used as a termination knot. A clove hitch meets the same criteria.
Prefer not to use a friction hitch for a pull down, since it can slide down to the termination knot (this happened)
Prefer not to use a buntline termination. I've imagined a certain bump that could loosen it.
Thus I came to the combination standard bowline plus butterfly.
if the bowline rolls out, the butterfly is situated as an in line knot
other combination knots are possible: F8OB termination with butterfly as pull down.




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Jim,
As I mentioned at the Rendevous, take a close look at your Bowline knot. I believe the one you illustrate is tied with the tail on the "wrong" side of the tree. Since we are viewing it from the back side ( tree side ) of the knot, the bunny should have gone around the left side (as shown) and back down the hole on the right side of the tree. Just being picky I guess.
Wiley Coyote

Hey Wiley...thanks for reminding me...I regard this as a mirror image that works as well as the opposite image...I'm not saying that I'm right - just sharing where my head is on this...What do you think?...Jim