11

As, I have been using a Double Fisherman's knot to join the two ropes. With some physics that I know, in Double Fisherman's knot the same amount of pressure (stress) is applied over the two turns of each rope, so making sure there is no significant damage done to any of the rope.

However I believe that if the two ropes are not of equal thickness, or may be say if the difference between the thicknesses is a considerably huge, Double Fisherman's would(?) do some damage to the thinner rope.

In that case how trustworthy are Sheet Bend and Zappelin Bend?

Edit: I am Not going to use this for rappelling at all. I intend to use that as a holding line when me and friends are swimming in a lake nearby. Having said this, We are not entirely relying on this as well.

Improve this question
4
  • 1
    What thickness of ropes are you trying to join? Is this for rappelling? A "sheet bend" will join 2 ropes, but I've never seen it recommended for rappelling. If you're trying to join a pair of climbing ropes (i.e., a single rope and a halfrope, or a single rope and a twin rope) there's probably a more specific recommendation
    – DavidR
    Commented Sep 21, 2013 at 13:12
  • 2
    I assumed op was not referring to Climbing or Rappelling since there were no tags mentioning these. Perhaps WedaPashi could clarify this for us.
    – Dopeybob435
    Commented Sep 21, 2013 at 16:07
  • @DavidR: Yes Sir, I am Not going to use this for rappelling at all. I intend to use that as a holding line when me and friends a re swimming in a lake nearby. Having said this, We are not entirely relying on this as well.
    – WedaPashi ♦
    Commented Sep 23, 2013 at 4:55
  • @WedaPashi you're going to use it to tie yourselves together while swimming?
    – Dopeybob435
    Commented Sep 24, 2013 at 12:41

3 Answers 3

Reset to default
15

A Sheet Bend is designed for joining two lines of different size. If you need additional security use the Double Sheet Bend

http://www.animatedknots.com/sheetbend/

Improve this answer
2
  • 6
    Anyone reading this should note that this knot is absolutely not safe for climbing.
    – Felix
    Commented Sep 27, 2013 at 14:36
  • 2
    @Felix The question never referenced climbing and includes the statement that 'I am Not going to use this for rappelling'
    – Dopeybob435
    Commented Sep 27, 2013 at 19:25
7

What is your intended use for those joined ropes? If your life depends on it (you tagged your question with "safety"), I would not recommend using drastically different sized ropes in the first place and I would recommend something that has been well tested by the rock-climbing community. Most rock climbers either join their ropes with the double fisherman's (without any damage, as far as I know,) or, when the profile of the knot needs to be small, the overhand knot with lots of tail.

I have not heard of the double fisherman's damaging ropes, where did you hear that?

Improve this answer
9
  • yeah, I am NOT going to use it for Rappelling at all. I intend to use that as a holding line when me and friends a re swimming in a lake nearby. Having said this, We are not entirely relying on this as well.
    – WedaPashi ♦
    Commented Sep 23, 2013 at 4:54
  • 1
    VERY IMPORTANT: The overhand knot must be tied on a bend. Because it looks scary (yet is perfectly safe), climbers call this the European Death Knot, or EDK: animatedknots.com/flatoverhand/index.php
    – Lagerbaer
    Commented Sep 23, 2013 at 16:26
  • 1
    @Lagerbaer Are you saying overhand on a bend for drastically differently sized lines? I don't see that knot working in the scenario described so clarity helps.
    – Dopeybob435
    Commented Sep 24, 2013 at 12:39
  • My scenario is intended for equally sized ropes, which is the scenario where rock climbers use the overhand knot. But again, it has to be the correct version of the overhand (EDK).
    – Lagerbaer
    Commented Sep 24, 2013 at 17:24
  • 1
    @BenCrowell: For activities related to rappelling (where the profile of the knot matters) I do advocate using the overhand with ropes that are commonly used for climbing. There is an interesting blog article based on some test-data the author linked to at the end of the article. I haven't heard of anything going wrong with ropes that have sensible differences in diameter, but if you know of any incidences or testing that show the contrary, please share!
    – DudeOnRock
    Commented Sep 27, 2013 at 23:02
1

If I was going to rappel on it, and the bulk of the knot wasn't an issue, I would tie a figure-eight in a bight of one piece of rope, then attach the other rope to it using a rewoven figure-eight. This way the knots that had to hold in order to keep me from getting killed would be two almost independent knots, each of which was tied in a single type of rope, and each of which was a standard type of knot (figure-eight) that is widely used in climbing and known to be safe.

As Dopeybob435 has pointed out, this is really a classic application of a sheet bend, but for a life-critical application I would prefer to use something based on a knot that was totally standard for climbing, both so I could be sure of tying it correctly and so that my climbing partner could check my knot.

Improve this answer
4
  • 3
    Sorry, but this is incorrect and unsafe. The double fisherman's or flat overhand are much better knots that do not have ropes rubbing on each other.
    – Felix
    Commented Sep 27, 2013 at 14:37
  • 1
    @Felix: I think you're incorrect, and in fact your suggestion would be the unsafe one. The knots you're suggesting are not intended for ropes of very unequal thickness and there's no reason to think they'd be secure in such a situation. Rubbing would only be an issue if one rope was to travel through a loop in another rope while under load. That's not the case here, where the two loops are like the links of a chain.
    – user2169
    Commented Sep 27, 2013 at 16:13
  • 2
    As discussed in the comments under DudeOnRock's answer, we may not be visualizing the same ratio of diameters. My answer is describing what I'd do if the ropes' diameters differed by a factor of 2, and in that situation I stand by my statement that your recommendations would be extremely dangerous.
    – user2169
    Commented Sep 28, 2013 at 0:33
  • You could adapt that approach to tie one figure 8 loop, then tie the other through and round it so as to look like a reef knot in the middle. Or tie them independently, then attach the two by passing a working end through the eye of the other rope then through the eye of the same rope. Same sort of thing as you would do to attach two slings, or rubber bands.
    – AdamV
    Commented Dec 3, 2018 at 14:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.