Rappelling knot for different diameter ropes

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Messages 1 - 20 of total 29 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
Impaler

Social climber
Berkeley
Topic Author's Original Post - Aug 16, 2012 - 01:38pm PT
My friend just e-mailed me this morning asking me to refresh his memory on the knot that we used for rappelling to join two different diameter ropes together. Well, I tried searching the intertubes and nothing turned up that looks like my knot. Someone told me that it's a figure 9, but the interwebs disagrees with me. I love the knot and have been using it for the last 1.5 years. I haven't died yet. It's very compact, has zero slippage and is easy to untie. So, I highly recommend it. The only critical issue is to make sure the strands alternate, so that they can tighten down each other. Can anyone help me out with the name of this thing?

Here I've tied a 7.5 mm tagline to a 9.4 mm lead rope, which is what I climb on nowadays on the bigger rocks:

Credit: Impaler

Credit: Impaler

Credit: Impaler

Credit: Impaler
crasic

climber
Aug 16, 2012 - 01:47pm PT
I'm pretty sure thats just a well dressed double overhand knot, not sure if thats better or worse then the single overhand (EDK) in terms of slippage...


edit: according some articles online its seems to me just fine, not that much stronger then a single overhand and more prone to get stuck, but if it gives you that piece of mind...


Personally, I either use just an EDK or a butterfly bend with the tails backed up with a single overhand on the tails.
James Doty

Trad climber
Phoenix, Az.
Aug 16, 2012 - 01:51pm PT
looks like a grapevine. same knot used for joining cordage just tied around itself using both strands. Should be bomber.
brawa

climber
SAN
Aug 16, 2012 - 01:54pm PT
http://www.blackdiamondequipment.com/fr-fr/journal/climb/all/qc-lab-what-is-the-best-rappel-knot

I've always heard that if using the EDK it helps to use the fatter rope as a block for the smaller rope. Here's an illustration:

http://vikingalpinism.blogspot.com/2012/08/using-overhand-knot-with-ropes-of.html
ec

climber
ca
Aug 16, 2012 - 02:00pm PT
Square Knot, finish the ends with a Grapevine Dbl Fisherman's

Edit: had to find a copy of my resource online:

http://books.google.com/books?id=Tu_5TL_Ci8kC&pg=PA106&lpg=PA106&ots=W6oNJOBV78&dq=square+knot+grapevine+knot+rappel&output=html_text
crasic

climber
Aug 16, 2012 - 02:04pm PT
Square Knot,

Not sure thats right, I just tried tying your bog standard double overhand and dressed it to be just like the OP.

ec

climber
ca
Aug 16, 2012 - 02:06pm PT
Check above.

I have used this as well.

 ec
Impaler

Social climber
Berkeley
Topic Author's Reply - Aug 16, 2012 - 02:12pm PT
So, I think it is some type of a double overhand knot. However, I have yet to see it tied in both ropes simultaneously. There are a couple of instructional pages that use a double overhand in EACH strand of rope and then the two knots are pulled against each other. That way the two ropes come out of the different sides of the knot. In my knot both ropes point the same way.

It looks like grapevine is a synonym for double fisherman
crasic

climber
Aug 16, 2012 - 02:27pm PT
For a square knot, the tails are on opposite sides, on this knot the tails are on the same side, I may be wrong and the square looks like this when tied in a special way but here is my replication using a bog standard double overhand
1 - open loop both tails on the right
1 - open loop both tails on the right
Credit: crasic

One pass through - EDK
One pass through - EDK
Credit: crasic

Double overhand
Double overhand
Credit: crasic


tightened &#40;ugly&#41;
tightened (ugly)
Credit: crasic

dressed  both tails on the right, notice the alternating pattern of st...
dressed both tails on the right, notice the alternating pattern of strands
Credit: crasic
hillrat

Trad climber
reno, nv
Aug 16, 2012 - 02:32pm PT
Someone should pull-test this. It,s a flat double overhand, which i,ve not yet seen data on.
crasic

climber
Aug 16, 2012 - 02:34pm PT
Someone should pull-test this. It,s a flat double overhand, which i,ve not yet seen data on.

Indeed, I'm curious too. There is anecdotal evidence online saying its just as good as a single overhand under standard static pulls, but no actual numbers
Impaler

Social climber
Berkeley
Topic Author's Reply - Aug 16, 2012 - 02:35pm PT
Crasic, thanks for the replies! Yes, it's the same knot. You just started tying yours differently, but the result is the same.

Hillrat, that would be nice. I think it's a good and simple knot.
Elcapinyoazz

Social climber
Joshua Tree
Aug 16, 2012 - 03:06pm PT
OP's knot looks like a flat double fishermans. Performed exceptionally well in testing from what I recall.

Personally, I use a well dressed, prestressed EDK. On a rare occasion I'll the flemish bend (more if I'm joining two ropes for a long fixed line, almost never for a rap type setup).
Malemute

Ice climber
the ghost
Aug 16, 2012 - 03:35pm PT
I've been an advocate of this double overhand bend (DOB) for a number of years.


http://www.supertopo.com/climbing/thread.php?topic_id=1165306&msg=1165809#msg1165809
http://www.supertopo.com/climbing/thread.php?topic_id=1412938&msg=1413874#msg1413874

I've tested a variety of knots in cord and this one is good.
Doesn't need long tails; will not roll under heavy load like an EDK does.
Easy to tie, easy to untie.
No keeper knot to jam.
Knot is to one side, like the EDK, so less likely to hang up.

Probably easier to tie than a Figure 9.

Kolin Powick replied 25/01/11 regarding testing it:
I just looked at this quickly – isn’t it pretty much a fishermans – but both ends coming in from the same side?
I can test it – as in a rappel setup – yes?
It’ll be burly – that’s for sure
Most rappel knots are way overkill considering the relatively low loads of a typical rappelling scenario.
Stand by – it may take me a bit
Kolin
.
crasic

climber
Aug 16, 2012 - 03:41pm PT
OP's knot looks like a flat double fishermans.

Thats a different knot, although it looks similar, there would be two crossing strands on the back side, this is just a double overhand. Basically an EDK twice over.


Here are both knots tied on the same pair of strands, bottom knot (right) is the flat double fishermans (double fishermans tied with strands in the same direction) and the top knot (left) is the the flat double overhand.


one side flat double overhand &#40;left&#41;, flat double fishermans &#40;right&#41;
one side flat double overhand (left), flat double fishermans (right)
Credit: crasic

other side, flat double overhand &#40;left&#41; flat double fishermans &#40;right&#41;
other side, flat double overhand (left) flat double fishermans (right)
Credit: crasic


This here is what I've been playing around with alpine butterfly bend with and EDK backup, fast to tie, hard to screw up, as bombproof as the flemish (figure 8 follow through) but assymeterical so it won't get stuck. Backed up with an overhand.

Credit: crasic


Malemute

Ice climber
the ghost
Aug 16, 2012 - 09:59pm PT
If you want a fancy rappel knot, here's the handshake knot.
photo not found
Missing photo ID#259422
Lower profile than the DOB, but the DOB is easier to tie.
I'll leave the method of tying as an exercise.
wivanoff

Trad climber
CT
Aug 17, 2012 - 07:50am PT
That DOB is an interesting knot. I've never seen that one before.

I've been using the flat overhand (EDK) with similar size ropes and a flat double fisherman's (ends coming out the same side) for different size ropes.

I'm wondering how easy the DOB is to untie after loading (compared to the flat double fisherman's)? It sure is easier to tie.
cliffhanger

Trad climber
California
Aug 17, 2012 - 11:16am PT
Nice knot, the Double Overhand (DOB). It solves the dangerous slippage of the EDK.

To make the DOB easier to untie, tie it as shown by Crasic, but tighten it so the the lower wrap does not ride up and over. You will end up with a knot that looks like half of a pursik knot that will be much easier to untie.
ruppell

climber
Aug 17, 2012 - 01:18pm PT
The double becket bend it what I've always used for different sized ropes. Easy to tie and bomber. Just make sure both tag ends are off the same side of the knot or your gonna die.

Becket Bend
Reilly

Mountain climber
The Other Monrovia- CA
Aug 17, 2012 - 01:27pm PT
^^^^ I don't know how Samuell Beckett insinuated himself into the knott business
but those Irish are a tiresomely sneaky lot. That looks a regular old
sheet bend to me which is what a sailor turned climber always uses to tie
different sized ropes together. I would usually make two bights of the
smaller rope with, of course, both ends half-hitched. It is also very easy
to untie.
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