tying ropes together to rappel

[Barnacle Ben]

Caribe, the links found on the wikipedia page you posted above have the evidence you're looking for.

[caribe]

THB: I thought this was pretty kool . . .
"Edelrid tests - (in German, with much of it translated into English). Test data on three knots: the flat-overhand, the double-fisherman's tied as a flat-knot (photo at right from their page), and on a new type of flat-knot. He translates it as "Triple Fisherman's", but it's not. The flat-double-fisherman's didn't invert at all in his tests. Cool! People have asked me about it, but I haven't done any tests."
from
http://www.xmission.com/~tmoyer/testing/EDK.html

[Shamis]

Just wanted to say that I love the traced through figure 8 for rapping, but I wanted to warn that it DOES get stuck a lot, and for multi-pitch routes getting your rope stuck while rapping can lead to very dangerous problems.

EDK is the best knot when you are in a situation where a stuck rope means you might end up sitting in the dark cold weather 1000 feet up for several hours, or all night...

[Jay]

can anyone help me understand why the flat overhand is considered safe whereas the flat eight is not?- in that it seems counter-intuitive that an additional twist ('bight' ? [edit-a quick search indicates that this use of the word 'bight' is NOT correct]) is the only difference, ....right?

The reason the overhand is safe, while the flat eight isn't, is that an eight consumes a great deal of tail when it inverts, nearly a foot if I remember correctly, while an overhand only consumes about three inches. This, in conjunction with the eight's tendency to want to roll, make it an unsafe knot. The overhand, while it may roll a bit, tends to tighten on itself, and really can't roll more than once, maybe twice if it was tied really loosely (i.e., barely tied at all).

The flemish bend and double fisherman's are both plenty strong for rapping, but the single overhand really does get stuck less, especially in situations when the anchor isn't right at the lip, or the rock has cracks which tend to be either flaring or irregular (Vedauwoo and Seneca come to mind)

[rjackson]

Man, there is only so much you can back up - you just cannot "back it all up", sometimes you just need to know what is good and what isn't. I guess you climb with double ropes, with two belayers with separate harness and atc's, etc - right? Ever look at the little pin that holds a gri-gri together? Are you one of those people that won't rap off a single 1/2" quicklink attached to two bolts, because it is a single point of failure?

Dude, I give up. You obviously know way more than me and I'm just (sh)it.

But as a parting gift...

If it's easy to throw an overhand on an extended tail, I do. If I've got an extra piece to plug at an anchor, I do. If I've looked at the webbing once, I'll look at it twice. I'll check it twice when cleaning, then check it again.

I take risks, but there's nothing wrong with with trying to reduce them when possible.

So...

Oh wise sage, lead on and educate us all, as we are ignorant and lost.

[KD]

"oh that's ignorant - don't be ignorant" (Michael Jackson)

[stix]

edk fo life!!!

wes and karsten are on the right track here. being aware of the situation and experienced enough to make and educated decision is the way to go. i'm very weary of the "i always" blanket statements.

if "X" is strong enough and qualified to do the job
and "Y" is stronger than "X" and also qualified to do the job
is "Y" better or safer than "X" for given job
NO it's only stronger (and most likely, but not always, heavier, slower, bulkier, etc. . . )

[KD]

so if x was a hooker and Y was a big fat chick then....?

[stix]

so if x was a hooker and Y was a big fat chick then....?

a question for the good ole days, when climbing was dangerous and sex was safe

[TradMike]

EDK death
http://www.geocities.com/danielzimmerli ... /knot.html