Sheet Bend Rope Extension

Notes and Resources:

Overview

This method of rope extension allows you to join a new rope anywhere along an old rope; it does not depend on end knots to stay put. It lays flat against the body, and can be easily adjusted after tying by sliding a bit of slack through the knot in order to fine-tune its positioning (for example, so that it doesn't wind up right on a collarbone).

It takes a little practice to get the hang of this method, but once you learn the motion it can be done very fast. I use this almost 100% of the time for extending ropes.

Note that it's very hard to tie this if the rope you're extending is slack; try to situate yourself so that you can keep tension on the old line while adding the new one. Sometimes I move my body away from my bottom while tying, to accomplish this, if I'm extending a rope that is still more than a couple inches long.

A bend is the name for a knot that joins two ropes, and a Sheet Bend is one of the most popular. This slight variation doesn't have a standard name, but could be called a Sheet Bend on a Bight.

Can this be used for suspension?

For tying suspension harnesses, yes, this knot is as or more secure than other common techniques. Compared to a collapsed lark's head, it is better-studied as a bend and likely more reliable. Compared to a non-collapsed lark's head (i.e. one just holding against end knots), it is both more reliable (because end knots can come out), and stronger (because it loads both sides of the doubled rope, as opposed to if ends are not perfectly even, a lark's head only fully loads one rope).

I do not recommend extending suspension support lines, regardless of the bend used, because it can cause it to be difficult to lower in emergency situations (due to the knot getting stuck somewhere in the system). Use long support lines that you won't need to extend, and don't use the leftover rope from harnesses as an upline. But, in some weird edge case where you did want to extend a support line, this might be a reasonable technique to use (except in exotic synthetics, where it may not be secure). I would not use this for rigging a hardpoint; more secure techniques are better suited for above the ring.

Needed for:
Other ties related to: Extending Rope

Comments

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    ShadowSoul42 | Mar 14th, 2017 6:23pm PDT #

    very cool. now i dont have to knot most of my ends.

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      Rahere | Apr 8th, 2019 12:41pm PDT #

      A better reason for this is if you have to undo a rigging in a hurry: knots can jam under strain. Yes, you have shears to cut them loose, don't you? But if you can take the tails out easily, one less headache.

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      Fyrebyrd | Aug 1st, 2017 6:18pm PDT #

      This is much nicer than the way I was joining. The ropes stay flat with no twisting.

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        felixdartmouth | Sep 17th, 2017 5:04pm PDT #

        Also, it pulls more evenly on both ropes, whereas the larkshead join can pull more on one rope than then other, creating unevenness.

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          CanisLupus | Jan 27th, 2020 1:29pm PST #

          To untie, a larkhead join can be very easily undone by just taking the 'bight' of it between two fingers and pull. What is the easiast way to undo this sheet bend join?

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            Topologist | Jan 27th, 2020 5:18pm PST #

            With one hand, grab the bight of the new rope. With the other hand, grab the old rope right where it comes out through the bight, on the side away from the body. Pull the two in opposite directions, and it comes right apart.

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          meurglys | Oct 21st, 2017 11:28am PDT #

          Very nice, quick and secure.

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            pleasedonotstop | Nov 17th, 2017 1:07am PST #

            Very nice ! Is it appropriate to use it to join suspension lines? If not, what would you recommend to join suspension lines/extend a suspension line ? Thanks !!

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              Topologist | Nov 26th, 2017 2:59pm PST #

              While this is a fairly secure bend, I'd recommend against extending suspension lines in general -- not so much because the join might come undone, as because it won't slide through your ring/biners/hanger smoothly or at all. Try to stay out of situations where you're using a support line that is not long enough to lower all the way to the ground with.

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                Rahere | Apr 8th, 2019 12:46pm PDT #

                How do you feel about using a larger line (say, 8mm vs 6mm for harness work) for suspension lines? I'm very glad to see the gradual disappearance of the "8m and nothing else" camp, in passing: the right tool for the job includes the right line length. The reason for this is because every knot in a line reduces the strength locally by 40% at the very least, even a friction wrap. Therefore, joining lines may be needed in drafting a scene, but once sorted, record it. Keep a notebook, so if you want to come back to it again, you have a refresher on the lessons you learned.

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              squeezysoap | Feb 8th, 2021 4:40am PST #

              I was previously using the collapsed larks head/square knot to extend rope, but this is far better. Built-in control over the lay of the strands, adjustable length, lies flat, instant release when untensioned.

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                johnjanklet | Mar 6th, 2021 11:06am PST #

                This is nice on synthetic rope. I'll have to use this more often.

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                  H3roFromSpace | Jul 20th, 2022 7:20pm PDT #

                  What are the benefits to the vs. the collapsed larks head to join the ropes?

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                    Topologist | Jul 22nd, 2022 7:42am PDT #

                    I find it easier to fine-tune the placement, and it is gentler on loose-laid ropes.

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                    nikemulders | Jan 28th, 2024 1:11pm PST #

                    What rope material and diameter are you using in this video?

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