Best way to tie two ropes together for rapping?
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Cor wrote:on another note... what is the stregnth of the edk, and the stregnth of a double fishermans? i was wondering about a edk for a cordelette instead of a double fishermans. it could be untied real easy for a number of tasks that you may use a cordelette for. anyone have any wisdom on this?Why tie any knot at all in your cordelette? Just leave the untied ends of the cord hanging down at your masterpoint. You will still have a MP of 2 loops which is fully redundant, and you don't have the added bulk of a knot on your harness. John Long's equallette only has a 2 strand MP so I'm not concerned about losing a strand. I started doing this a while back and have no regrets at all. It's double useful when using 5.5mm spectra - no triple fisherman to really bulk things up. |
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JPVallone wrote: Tony the EDK can roll over edges, yes it can still get stuck, but less likely then a double fishermansBecause lots of people use something doesn't mean it's the most reliable option. (I've yet to see a Honda Civic with 200 000Km on the counter ;) ) The "only EDK avoid getting stuck" is not true. The EDK is not the only asymetrical knots out there: For example this one above^^: the double fisherman in a flat setup (aka DT-FK). Look at this page (have it translated from German to English): gudelius.de/spst.htm "DT-FK kept his form and made it to a load of between 2100 and 2800 daN"(that's decanewton, or approximately 10 newton) the DT-FK appear to be approximately 15% stronger than an EDK. Plus, if you do a tripple instead of a double (which really doesn't take a lot more rope, time or complexity), if you miss-tie it, it will (most likely, depending on your mistake) fall back into a double fisherman anyways. Miss tying an EDK is way scarier IMO... (especially for whoever brought up the "I'm tired and I just bomb an EDK". Being tired = more prone to errors) Yes the double(or tripple) fisherman knot, wether the conventional setup of the flat knot setup) takes a longer to do than an EDK, but it seem to be more mistake-proof and better with rope of a different diameter (In my case my new rope is a 9.5, and my old ropes are 10.2+... I don't feel safe with an EDK as strand tend to want to roll over each other given the difference in diameter) Even very loose, the Double fisherman in flat knot setup will constrict in a way that makes the loop go smaller, not allowing the room for the "top" fisherman knot to go throught. And that remain true even if the rope from the bottom knot is completely removed from the top knot. I can't find a lot of documentation on that knot, but from what it can see with my very unqualified opinion, if seem to be a knot that is: + 15% stronger than EDK + that allow room for error, especially if you take the habbit of doing a tripple fisherman. + Does not roll if loose of under high loads. + Is just as asymetrical as the EDK. - But takes longer to execute. ( But most people --ie.: sport climber-- can afford an extra 45 second ) Anyone can comment on the downside of the double fisherman in flat setup ? Thanks ! |
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Brian in SLC wrote: Knot cinched down, no rolling and/or capsizing.Have you tried your tests with crossing strands ? In some case it seem if there's a strand crossing and you're not pulling all 4 strands properly, the knot can roll up to twice under 400lbs: See some testing made by Tom Moyer; Test 11, 14, 16 ... and they are all same diameter rope. (I imagine thoses 'mistakes' tests with different diameter wouldn't be any better) user.xmission.com/~tmoyer/t… I think as far as the "wet ropes" thing, it's just the same as lubing your rope: it reduce friction between the strands inside the knot. Having a different diameter also makes it easier for the strand to move into a different configuration, which in turn may or may not weaken the knot (depending on the resulting knot). Ps.: Sorry for re-activating an old thread ! ;) ... I just have problem with the very basic mentality of seeing people saying to leave almost 2' of extra rope as "it's a knot that is likely to roll". Makes me shivers: put a stop knot instead: if it rolled once, it could roll twice ! |
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Fmaz wrote: Because lots of people use something doesn't mean it's the most reliable option. (I've yet to see a Honda Civic with 200 000Km on the counter ;) ) The "only EDK avoid getting stuck" is not true. The EDK is not the only asymetrical knots out there: For example this one above^^: the double fisherman in a flat setup (aka DT-FK).I've been using the EDK for a long time, but once I became aware of this flavor of the double fisherman I made the switch. It has the benefit of the EDK (rolls easily over an edge) without the sketchiness of the knot rolling/capsizing. Best of both worlds! It is harder to untie compare to the EDK, but ideally the only time you need to untie it is when you're done rapping and safely back on the ground. |
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Fmaz wrote: Because lots of people use something doesn't mean it's the most reliable option. (I've yet to see a Honda Civic with 200 000Km on the counter ;)I drive a Civic with 260,000 km on the odometer right now and sold my prior Civic still runnning after 420,000 KM. Not that unusual. Did I miss all the reports of rappeling deaths from EDKs? |
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Mark E Dixon wrote: I drive a Civic with 260,000 km on the odometer right now and sold my prior Civic still runnning after 420,000 KM. Not that unusual. Did I miss all the reports of rappeling deaths from EDKs?Darn; everytime I try to do a car analogy, it turn againt me, haha ! My point is simply: Good is great, but better is better. If you are to learn a new technique, just learn the best one. Doesn't mean other techniques are bad per say. To answer your question, there's at least the incident with Karen Turk, not a death report, but close call: "When Turk was approximately 30 feet above the ledge, Dagher states that she watched the knot unravel, causing Turk to fall. Turk fell about 15 to 20 feet, struck her back against a rock prow, then fell another ten to 15 feet onto the ledge, landing on her back. Goewert said that Turk never lost consciousness, but was in significant pain. In conducting a physical assessment of Turk, he found a large laceration across her lower back, with exposed spine, but no other significant injuries. [...] Goewert, an experienced lead climber, said that hes been using the overhand knot for a couple of years, but has always been a little uncomfortable with it. He added that its a knot used by a lot of climbers he knows. Hes not sure why the knot came untied. It had held multiple rappels and, after having been loosened, had been re-secured by himself and rappelled on once again. Goewert added that he would no longer use this knot. [...] She(Turk) could offer no additional information surrounding the nature of the accident, but added that Dagher had made a comment about the knot, to the effect that it looked pretty weird and she wasnt clear how it could hold. This comment was made at the last rappel station. Turk said she was aware that Goewert had adjusted the knot at this station but did not see him do so. " |
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Flat overhand w/ a backup. Easy to tie, easy to check and easy to untie after weighting.... There is a great tutorial on how to tie it on a blog I follow: |
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Not mentioned by Fmaz: |
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i just do a square knot. Havent died yet! |
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The flat double fishermans also has a well known failure mode in that it can separate on the pull. If the black rope's knot in fmaz's photo gets caught on something, it can pull off the end of the red rope when you start yarding on the thing. There is some info on this issue online...I believe the solution is to use a 'triple overhand' or back it up in some way. But then you end up with a pretty massive, non-intuitive thing. You can see the triple overhand here: gudelius.de/spst.htm |
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I always use a simple overhand (EDK) with long tails (18") and hand tighten each of the four strands. |
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Xam wrote:The flat double fishermans also has a well known failure mode in that it can separate on the pull. If the black rope's knot in fmaz's photo gets caught on something, it can pull off the end of the red rope when you start yarding on the thing. There is some info on this issue online...I believe the solution is to use a 'triple overhand' or back it up in some way. But then you end up with a pretty massive, non-intuitive thing. You can see the triple overhand here: gudelius.de/spst.htmI wouldn't say it's impossible, but I would say it's improbable. Let's just assume for a second that it's possible to miss the knot on the red rope and only get the knot on the black rope caught on something, and the end of the red rope is smooth enough so the strangle knot on the black rope can easily slip off the end. At this point, you still have a strangle knot on the black rope and a strangle knot on the red rope, so they will not pull free of each other unless the strangle knot on the black knot comes completely undone. But wait, the strangle knot on the black rope has to catch on something for this scenario to happen in the first place... once the strangle knot on the black rope comes undone, the black rope is to free to be pulled again. So in essence, two contradicting conditions have to exist for this scenario to happen. I would say that's highly improbable. And let's assume against all odds the red rope does pull free of the black rope... then you have a free rope and a stuck rope, vs. two stuck ropes. Wouldn't that actually be a good thing? (Unless you're lowering someone with the two ropes tied together, or rappelling with the red rope fixed in your device and the black rope sliding - essentially pulling on the red rope) |
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I'm so glad there is an alternative to the EDK. Mine has failed three times now. |
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Xam wrote:The flat double fishermans also has a well known failure mode in that it can separate on the pull. If the black rope's knot in fmaz's photo gets caught on something, it can pull off the end of the red rope when you start yarding on the thing. There is some info on this issue online...I believe the solution is to use a 'triple overhand' or back it up in some way. But then you end up with a pretty massive, non-intuitive thing. You can see the triple overhand here: gudelius.de/spst.htmThe double flat fishermans does not fail in the circumstance you describe. What happens is you would lose one strand on the pull. I first learned about these knots years ago when published by Edelrid and I did settle on the triple. This is really hair splitting but I would like to see edge pull test comparisons between the triple and the EDk, I think the triple would do slightly better. The triple does have a tiny bit more bulk though. Nothing wrong with a little knot geekery but if I am with someone who rigs an EDK for double rope rappel, I would not hesitate to use it. |
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Xam wrote:The flat double fishermans also has a well known failure mode in that it can separate on the pull.A well known failure mode that can only happen when you are done rappelling, are pulling your rope down and has never been reported as actually happening in the real world? I think I'll continue to use it. |
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Rick Blair wrote: The double flat fishermans does not fail in the circumstance you describe. What happens is you would lose one strand on the pull.I am confused...isn't that what I said? Truthfully, I don't think it matters which one you use. I am just pointing out that the flat fishermans isn't the panacea it's made out to be above. The edk can roll at forces you will never obtain rappelling and the flat double fisherman has a non-zero chance of coming apart on the pull. Use whatever makes you happy. |
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steve edwards wrote: I use a figure 8 version of the Euro Death Knot. It still rolls out of the way of obstacles and seems a bit harder to get unlodged. I'm not sure why anyone would use a double fisherman's. It looks cool, maybe, but it's like climbing with hexes and EBs. Fig 8 follow through is very safe but bulky and can get hung up more easily than the death knot. I hope this person is safe and sound. Figure 8 version od EDK is a very bad idea and cause of many fatalities. |
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Luis Armando Gil wrote: Since he replied to this 7+ year old thread on the first page saying thanks, and that he'd changed back to EDK I don't think you need to worry too much... |