tying ropes together to rappel

Post by **Wes** » Mon Dec 21, 2009 9:49 pm

FujManiac, Yes, that is correct. Leaving long tails is a kinda backup, as if the knot fails, it just sorta reties itself into the same thing. So, with 10" tails, it can do that a couple times, and you are still fine.

rjackson wrote:I back it all up. You can think it will never happen to you, but it will. You get one shot.

It's your life...

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?

I think this is an Arno quote - but you can never be safe, you can only be aware.

Post by **caribe** » Mon Dec 21, 2009 11:49 pm

FujManiac wrote:to clarify, the "single overhand," "European Death Knot" and "flat overhand" are all the same knot, correct? Simple and easy to tie, and is acceptable. And you do NOT have to back it up?

Right, start with two ropes parallel and the bend at the same length. Tie the single over hand bend with both ropes. Leave at least 12" of excess tail. If there is enough tension on the rope, it will roll a bit and as it does the knot will tighten. The rolling action has been noted to be a bit sketchy if the ropes greatly differ in diameter. I don't know how much difference is safe, but my 210 lb climbing partner and I did not have any problem with a 8.2 mm/ 9.8 mm rope combination (Petzl Dragonfly / Nomad) with the single overhand. The roll was barely perceptible. Because of previous comments I might add that both ropes were new and slick as hell.
bend = joining two ropes.
http://en.wikipedia.org/wiki/Euro_death-knot

Post by **clif** » Tue Dec 22, 2009 12:11 am

well holy god.

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?

Post by **TradMike** » Tue Dec 22, 2009 12:55 am

It is very important to note that the EKD can also invert leading to catastrophic knot failure if given insufficient tail. Make sure it is dressed nice. If it is not dressed nice it will continue to roll right off the ends.

Post by **kdelap** » Tue Dec 22, 2009 12:57 am

I use a variety of knots to rappel depending on the situation. Some of the variables are:

Rock type,
Rock quality,
Transition type as well as need for speed.

Savage,

Once you climb at Red Rocks you will see the need for the overhand.

Also this EDK was originally called the Patagonia knot. There has also never been a know death from a properly tied over hand.

My thoughts...

Post by **caribe** » Tue Dec 22, 2009 1:27 am

TradMike wrote:It is very important to note that the EKD can also invert leading to catastrophic knot failure if given insufficient tail. Make sure it is dressed nice. If it is not dressed nice it will continue to roll right off the ends.

I didn't think so. Do you have evidence even anecdotal evidence?

Post by **captain static** » Tue Dec 22, 2009 2:20 am

I have been climbing for over 30 years, am old school, always have used the double fishermans, done numerous double rope rappels, many in alpine conditions, am still alive, and have never had any epics pulling the rope. This is fairly objective and informative: http://www.blackdiamondequipment.com/en ... appel-knot

Post by **kdelap** » Tue Dec 22, 2009 2:30 am

I did some testing on the overhand rolling off the ends. With the machine that we had we could only to get it to roll once and then max out the machine around 2000 lbs of force. We did a couple that were very loose as well as not dressed well. Same result.

Captain,

The Black Diamond article is great. This really proves the point that all knots tested are strong enough for body weight rappelling. So choose the right one for the right situation.
As for the "I always" ; I try to stay away from this. There will most likely be some situation that would call for a change in tools I use and how they are applied.

Cheers,

Karsten

Post by **caribe** » Tue Dec 22, 2009 2:31 am

captain static wrote:I have been climbing for over 30 years, am old school, always have used the double fishermans, done numerous double rope rappels, many in alpine conditions, am still alive, and have never had any epics pulling the rope. This is fairly objective and informative: http://www.blackdiamondequipment.com/en ... appel-knot

But you posted a site whose author has converted to the double overhand . . .

Post by **THB** » Tue Dec 22, 2009 2:32 am

A few other resources you might want to check out...

http://www.xmission.com/~tmoyer/testing/EDK.html

and...

Rock & Ice issue 158 on pages 84 and 86... if you have a copy... check it out. In short, they rate 3 commonly used rap knots.

According to the article...

ring bend (water knot) - 4 stars (they recommend backing it up with an overhand with each tail)

double fisherman - 4 stars

euro death knot (edk) - 1 star

...personally, i prefer a traced 8 (flemish bend) backed up with half a double fisherman on each tail.

have fun! climb safe!