This is something I came up with while setting my rope oneday. WARNING... It is NOT to be used for life support!
Once your throw line is in place, thread the end of your climbing rope through the nylon loop on the bottom of your throw bag. Or the steel ring if your bag doesn't have the loop. Anyhow, once through simply tie an overhand knot around the running end of the rope. Sinch it up against the bag and you're ready to go. Basicly it's like a running bowline in its application. As long as it's application is light duty.
So there ya go. The Pennsylvania Jippy Slip.
I can see how tying the overhand around its own standing part reduces the tendancy of it to roll out - as long as you don't hang anything too heavy from it!
However, I find that knots can get wedged in the crotch when you try to pull the end of the rope over the branch. Instead, I tie the throwline to the end of the rope in a series of half hitches along the last few inches of rope befor its end. That way there's no bulky knots to pass over the crotch.
If I was tying the end of a rope to something just to haul something light then I use a buntline, which is as easy as an overhand knot but doesn't roll out as easily.
(The Tree Climber's Companion by Jeff Jepson originally taught me both of these things!)
michaelspraggon, I agree with you about the dreaded crotch grab potential you mentioned. My primary method of rope attatchment to the throwline is as you mentioned, with the series of half hitches as mentioned in Jepsons book. But if I'm setting my line over a clear branch with no tight crotch to worry about, this is when I use the jippy slip. It's just so much quicker.
Davej, I may have been a bit too vague on my intial post of this knots use. I'm not attatching my climbing rope to the throw bag to try to set it directly. I set my throwline first. Then I attatch my rope to the bag inorder to haul the rope up into the canopy. I climb a lot of wild trees. It's frustrating enough having to rescue an errant throwline snag. There's no way I would risk it on a high set with my rope.
A little off subject but still throwline related......
What type of throwline do you use. Zing it, Fling it, something cheap from the local hardware store?
I use Zing it for my new big shot, 3/16 nylon for my short throwline, and either 3/16 nylon or a braided masons line (Which is about the same size of Zing it) for my long throwline. All seem to work well.
I also use 1/4 yellow poly as a leave-it-in-the-tree line if I'm planning on climbing the tree again with the same tie in point.
A version of the Jippy Slip was featured on the Working Climber. I have not had a chance to try it out yet. Sounds like tree conditions would have to be just right to use it. I could imagine the time savings though.
I use zing-it. I have used cheaper stuff off the shelf in the past. It was some kind of nylon twine, about the same thickness as zing-it. Problem was that if you breathed in its general direction when you threw it it got all tangled, self knotted... I hated it. I have also used a parachute type cord that's 1/8th". This worked pretty good, but would get stuck on any kind of rough bark. Like on a black cherry or silver maple for instance. I still use this stuff on ocasion. Especially if I'm on a work site that's gonna take a couple of days climbing and I want to have my main TIP readily available the next day. It's dark green, so it blends in real well with the bark.
We use Zing-It here in England too. Being bright yellow it's easy to see which branch it has gone over and it's much lower friction than the nylon cord I bought from my local hardware store years ago. It still gets caught sometimes under the bark of certain trees like Scots Pines for example.