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Abseiling knot - asymmetrical double fishermans

koala

9-Mar-2006
4:03:00 PM

I saw what looked to be this knot mentioned very briefly on some climbing/abseiling websites. I am seeking opinions from old hands out there, on weather they consider it a good knot for tying two ropes together for abseiling, particularly ropes of differing diameters.
The knot starts by bringing the rope ends together - (a) and (b), tying a fishermans bend from (a) over its neighbor (b), then tying another fishermans bend from (b) over the tail of (a). Snug up tightly. This would seem to have the advantages of the asymmetrical knot - clearing rock edges, with the ability to join differing diameter ropes.
Cheers ...

Nick Kaz

9-Mar-2006
5:23:23 PM

My hands arent that old but I think that:
It takes a while to tie, it takes ages to get undone after a fatty like me slides down it, it will bpobly get stuck just as often as an overhand. Overhands are the go, just give them a good tale and make shure they are tight.

shaggy

9-Mar-2006
11:00:04 PM

overhands dont work well on diff sized ropes

vwills

9-Mar-2006
11:05:30 PM

Not quite on topic, but its a great site about knots
http://www.animatedknots.com/indexclimbing.php?LogoImage=LogoGrog.jpg

Nick Kaz

10-Mar-2006
8:24:17 AM

whoops, thanks Shaggy guess you just have to live with the crappiness that is the fishermans.

Phil Box

10-Mar-2006
9:03:34 AM

I'm still a great fan of the overhand knot. I've actually used this knot for tieng unequal sized ropes together with no problems. Just make sure they are cinched down correctly and your golden.

I have used the asymetrical fishermans and although it is a very good knot I think it is overly large and may become stuck more times than the overhand.

uwhp510

10-Mar-2006
11:20:35 AM

The good old Euro death knot (overhand knot, named by freaked out americans) can't be beat for abseiling goodness.

gfdonc

10-Mar-2006
11:24:00 AM

Overhands flip over under load. It's been proven (sorry don't have the reference handy). If they flip over enough times the ropes become untied.

In practice this is fairly unlikely (needs high load) which is why there are still lots of climbers using this Alpine Death Knot who are still climbing.

Sorry to sound controversial but this is one area that I differ from some of my climbing companions hence forced under duress occasionally to rap using this setup! To reduce the risk, tie a second overhand in the free end, a few inches from the other. Then if it flips it will get stuck on the second knot, and can't flip to the end of the rope.

The other secondary risk is that ppl will see others doing this, and try doing the same but with a figure-8 instead of an overhand knot, thinking the fig-8 will be safer. It isn't! The 8 flips over at a lower load rating and is attributed to at least one death (check Zion report, Chockstone has a link from the Tips pages).

I still rap on double-fishermans by preference and cannot recall getting a rope stuck, ever. When I eventually do (as advocates of the ADK assure me will happen) I'll be comforted knowing the knots held safely all those years. ;-)
- Steve

Romfrantic

10-Mar-2006
11:28:36 AM

I agree with Phil - and as already mentioned by a few above, just leave a long tail (at least 30 cm) after knot has been tightened, then all's sweet.
That's a good site Vanessa.

uwhp510

10-Mar-2006
12:42:23 PM

I used to do a second backup knot before I fully embraced the ADK, but it seems like that other knot would be far more likely to get stuck, so now I just make sure the knot is sitting right and cinched tight and have never noticed any shifting of the knot what-so-ever.

It is so much easier to pull the ropes and to undo the knot afterwards.

Phil Box

10-Mar-2006
1:06:24 PM

Where did the ADK come from, I've always known it as the EDK aka the Euro Death Knot. I always tell people to put a metre of tail on it as well and then also give them the caution not to abseil on the short pieces of tail. ;))

koala

10-Mar-2006
2:10:08 PM

Thanks everyone, for your thoughts. I'll be canyoning at Kanangra this week end. Will use the the trusty overhand as I have in the past - with the overhand back-up as well. Was
just curious about this knot! ..... Cheers

DJ Biggs

10-Mar-2006
2:25:16 PM

I was told that the difference between when an overhand flipped it then locked ( in some self tightning thingy) unable to flip again, unlike a figure of eight which is able to continue flipping over untill the tails runout. It seems to make sense other wise I assume one would see more deaths from over hand knots.....or have I heard wrong?

gfdonc

10-Mar-2006
3:36:45 PM

On 10/03/2006 Phil Box wrote:
>Where did the ADK come from, I've always known it as the EDK aka the Euro
>Death Knot.

Yes, also called the EDK, but the partners I climb with aren't European, so I have to ascribe their knotting practices to some of their other character faults ;-)

Also re the comment about not rapping off the tails .. that possibility in itself would convince me 'knot' to use it.
Don't know what it is, but rapping/abseiling still scares me after all these years, I triple-check everything. Anything that makes it simpler and/or safer is a good thing.

Surprisingly to some, I admit I don't usually use a backup knot/autoblock, mainly to keep the system as simple as possible & ensure my focus stays on rigging and managing the belay device correctly.

gfdonc

10-Mar-2006
3:42:02 PM

While I think of it .. I've always been puzzled by the tips for autoblock knots to backup a rappel. The Chockstone tips are one example. The issue is that: all the diagrams/advice/knots refer to a single rope, but we all normally rap on double ropes, don't we? So the knots are supposed to be tied around both ropes?

Is this just an accidental omission, or are we supposed to assume the autoblock is only tied around one strand of a double-rope rappel (and we can all imagine what happens then)? Do (all of) these knots work when tied around two strands? (I've never tried).

Not really an issue for me - as I don't use this method - but someone reading the tips page might come to the wrong conclusion.
- Steve

cheesehead

10-Mar-2006
11:50:16 PM

Another solution I've been shown (but don't like) is tieing a reef knot in between the two fisherman's knots.
The reef knot is easy to untie after being loaded, but can't slip out, since each tail is cynched with a fishermans.

One trouble is that the fishermans knots on the end can't be cynched against each other, which is why they hold so well.

Phil Box

11-Mar-2006
11:30:52 AM

On 10/03/2006 gfdonc wrote:
>While I think of it .. I've always been puzzled by the tips for autoblock
>knots to backup a rappel. The Chockstone tips are one example. The issue
>is that: all the diagrams/advice/knots refer to a single rope, but we all
>normally rap on double ropes, don't we? So the knots are supposed to be
>tied around both ropes?
>
>Is this just an accidental omission, or are we supposed to assume the
>autoblock is only tied around one strand of a double-rope rappel (and we
>can all imagine what happens then)? Do (all of) these knots work when
>tied around two strands? (I've never tried).
>
>Not really an issue for me - as I don't use this method - but someone
>reading the tips page might come to the wrong conclusion.
>- Steve
>

The friction knots article refers to resaerch done on friction knots on one strand only abseiling rope. When transferred to two strands the autoblock knot in particular becomes even more effective. We do intend at some point in the future to do the full range of testing in a scientific manner on two strands.

When we train beginners we mostly teach them to abseil on one strand and place a top belay backup on them using the other strand thus the need to categorically confirm that the single rope friction knots system was effective and worked first time every time in all situations.

Of course most climbers use double ropes to rap off routes. We have found that 6mm cord is by far and away the most effective diameter for prussik loops to tie the autoblock knot. This is the most beneficial thing to come out of the research document and analysis. We shall be submitting another article to more fully explain the findings and their practical use in the near future.

climbau

11-Mar-2006
11:57:53 AM

I've been known to use an Alpine Butterfly (rope ends would be where the loop apex would be). It has the advantage of loading and running over edges like the overhand but won't roll over like the overhand. It is also really easy to undo and you can see if you have done it wrong.

P.S. I always taught folks to use 90mm tails (similar to Phil) on overhands, using a second overhand tends to defeat the purpose of using an overhand as the backup will inevitably get caught in a crack.

dr box

13-Mar-2006
4:25:29 PM

iy you dont like the overhand and you are sick of trying to undo a tight double fishermans try using a triple fishermans (that is one extra turn before you feed back on its self). i found them a lot easier to untie after abseiling, espeically after the rope is wet (canyoning more so)
the only down side is it uses more rope than a double fishermans...but whatever

There are 19 messages in this topic.