Author Topic: Loop suggestions for flat, tubular webbing. Zeppelin? Alpine butterfly? Others  (Read 11480 times)

AffableAlligator

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Hi everyone!

I've been a casual lurker for a while and really enjoy the IGKT forum!  I'm setting up a slackline today with 1" tubular webbing and I plan on creating a couple of simple tree anchors with loops on both ends to clip the main line.*  I'm just using a simple primitive setup**.

The water knot appears to be the only knot discussed anywhere online for use with flat webbing?and I assume a simple overhand loop will be fine (if impossible to untie).

Are there any other acceptable knots for use with flat tubular webbing?

It would be nice to have something with a high break strength and easy to untie.

I've played around with the zeppelin loop (though not under load, yet) and it seems ok.   It certainly takes some fussing to dress it properly.  The alpine butterfly seems to dress even better.  Flat webbing seems to be a mess for something like an EBDB, but I could be convinced.

Others?

I imagine the simple overhand loop is just fine, but this is fun to discuss!

Cheers!

*from what I gather in videos and online, a typical setup is to make a sling (a big loop) with a water knot and then wrap the sling around the tree (rope required is 2x diameter of the tree).  I don't have enough webbing for that, so I'm going with the two loop method.

**maybe too much info, but for posterity, this is what I'm doing (with the exception being the anchor):  http://www.nwslackline.org/96/howto-setting-up-a-basic-primitive-slackline  I plan on using between 30-60 ft long for my main line (maybe 1000 lbs of tension max).

roo

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Hi everyone!

I've been a casual lurker for a while and really enjoy the IGKT forum!  I'm setting up a slackline today with 1" tubular webbing and I plan on creating a couple of simple tree anchors with loops on both ends to clip the main line.*  I'm just using a simple primitive setup**.

The water knot appears to be the only knot discussed anywhere online for use with flat webbing?and I assume a simple overhand loop will be fine (if impossible to untie).

Are there any other acceptable knots for use with flat tubular webbing?

It would be nice to have something with a high break strength and easy to untie.

I've played around with the zeppelin loop (though not under load, yet) and it seems ok.   
While a Zeppelin Loop could work fine (pictures of the Zeppelin knot form in flat material), it doesn't seem like this application needs a high security loop since there shouldn't be much in the way of cyclical loading or loose flogging.  Could a simple bowline work, even if looks a little bunched up?  I'd also wonder if a hitch could be used on one side to directly attach to an anchor point.

And since it seems unlikely that one would want or need to load the webbing outside of a safe working load limit, the desire for a high-strength knot form seems like something that could be set aside.

As an aside, you may be interested in a Verstackle to use as a metal-free tensioner using rope on one end.  A permanent sewn eye in the webbing could be used as an interface for the Versatackle rope.
« Last Edit: July 22, 2012, 01:36:48 AM by roo »
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SS369

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Hi AffableAlligator and welcome.

Simply put, I would go ahead and purchase webbing of sufficient width and length (strength) to make slings long enough to wrap three coils around your anchor (tree?, if so protect the cambium with something!)  and use the ends of the sling connected with biners, etc to your mainline cinch.

A thousand pounds of tension is pretty hard on a knot and it will be a bear to untie most of them after that loading. My handmade slings are tied either using the water knot or the beer knot. They are permanent. 
In using a wrapping sling you will be dispersing a lot of the force around the anchor that would end up into the loop knots in your other method.

Many rope knots can be used for webbing, the kicker is if you'll be able to untie them.

Me, I would make some permanent slings for this (or purchase some) that exceed the demands of what you are going to do.

Good luck staying on the slackline. ;-)

SS

Dan_Lehman

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Are there any other acceptable knots for use with flat tubular webbing?

It would be nice to have something with a high break strength and easy to untie.
...
Flat webbing seems to be a mess for something like an EBDB, but I could be convinced.

Others?

I imagine the simple overhand loop is just fine, but this is fun to discuss!

Nice to see "flat tubular webbing", vs. the traditional contrasting
"flat" vs. "tubular" --better, IMO, for "solid" to be the contrasting
adjective, as all webbing is flat by definition!
 :)

You might simply insert some suitably sized dowel/pipe into an
overhand eyeknot for getting easier untying.

The EBDB is not something that should be thought of, as its
reason d'etre is one of security, primarily, and in rope not tape.
I've read someone assert that a bowline on a bight is stronger
than the overhand eyeknot, but I'd think one could use some
better bowlinesque knot, aiming to pad the flat material just so.

I'll suggest trying what I call the "symmetric fig.9 eyeknot" --a knot
that is topologically the same as the better-known fig.9 but takes
a symmetric orientation, and one that enables easy untying.

Here's a verbal illustration:
1) fold the rope into a bight running rightwards (ends left);

2) orient this bight so that the flat side faces you (narrow sides
up/down ; broad sides facing at/away from horizontal view);
and have the tail on your (viewer's front) side --towards you,
loaded end behind;

3) now, make a 270-degree loop by bending the bight around
anti-clockwise around and down behind itself, keeping the
tail on the inner side, loaded part exterior (so, where this
bent-around part crosses behind itself, it will be the folded
tail that could touch the horizontal loaded part);

4) bring this bent-around bight front and up through the
loop just formed (this will complete and overhand knot),
keeping the tail interior;

5) keep bending the bight anti-clockwise, tail part interior,
around itself and down in front of the horizontally
disposed standing part & tail-end and out through the
loop aspect formed as the bight was reaching up to complete
the overhand (if one were to do this behind the
horizontal parts, you'd form a double overhand).

Dress the knot by reducing material/span of the bottom
bent-around path and smoothing things out in general;
settting/tensioning is going to do some various crunching
and distorting the flat aspect of the tape in places, but
that's to be expected.

The general appearance of the knot is that the twinned
SPart & tail coming from the left reach into the knot and
curve upwards, and the twin eye legs similarly come in
from the right, almost like contestants of arm-wrestling.

I find the knot VERY easy to untie --that bottom span
just doesn't tighten (and why one wants to work out
excess material there), in most materials (ack, it DID
in the very slick HMPE 12-strand rope --darn tight!!).

I have no idea about the strength of this knot, but surmise
that it's decent; consider, that in the overhand eyeknot,
the material that "collars" the mainline is itself being loaded
by the eye --it's the eye legs--, whereas in this knot, that
material collaring the SPart+tail and in opp. side the eye
legs is *passive* --it's simply there, resisting, not loaded.


--dl*
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agent_smith

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Hello AffableAlligator,

Having read through some of the reply posts, it makes me wonder how many people actually setup and use slacklines on a regular basis. I do...

For starters, dont use knots in your slackline! (unless of course you plan to use a knife to cut all of your webbing/tape - any knot will be welded / fused to the point where it will no longer be humanly possible to untie it by hand.

You need a couple of forged metal rings and carabiners (see website below). Slackliners call them 'line-lockers'. You can pull a truck out of the bog with this system and its easy to untie it when finished (no fused knots).

Site: http://www.slackline.com/?tag=gear

For anchors around trees, the cheapest and most effective method is to use a 'wrap 3-pull 2' anchor. It is constructed from tape/webbing. Benefits include:
[ ] easy to untie - even after serious high loadings
[ ] easy on the bark of a tree
[ ] cheap
[ ] multi-directional

Just google 'wrap 3-pull 2'.... you'll get a million hits to look at.

Mark

roo

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For starters, dont use knots in your slackline! (unless of course you plan to use a knife to cut all of your webbing/tape - any knot will be welded / fused to the point where it will no longer be humanly possible to untie it by hand.
Let me guess:  You only use a water knot in webbing.
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Dan_Lehman

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For starters, dont use knots in your slackline!
(unless of course you plan to use a knife to cut all of your webbing/tape
- any knot will be welded / fused ...

I'd expect circumspection from one whose read these forum
posts over some years, and has seen novel ideas presented;
and especially given my reply here, which explicitly describes
a non-jamming knot!  To Roo's remark/point, have you ever
tried a bowline (on a bight?) ?!

Which is not to say, though, that advice to prefer other solutions
to such knots is wrong --it might be better, thus (even w/o jamming).

Quote
For anchors around trees, the cheapest and most effective method
is to use a 'wrap 3-pull 2' anchor. It is constructed from tape/webbing.

BUT, notably --and this is a hindrance/negative-- it is constucted
in situ (on-site) and not e.g. with a pre-tied (long) sling!
(Unless one can drop these wraps around the object --not w/a tree!)
Why this?
(prefer => "wrap-four-pull-two" = "full wrap, pull bight ends")

Quote
Benefits include:
[ ] easy to untie - even after serious high loadings
[ ] easy on the bark of a tree
[ ] cheap
[ ] multi-directional

The knot is situated to be at a 25% of load's tension
AFTER the material arcs half-way around the tree
--sufficient, by your (et al.') experience, and so any
"improvement" (i.e., lessening) of this is of scant value.
The simpler structure --simpler in being pre-tied, and
so merely wrapped fully (of a long sling)-- has the same
force reduction at the knot (twinned with an unknotted
span), and an extra part fully wrapping the tree; it's
thus that "extra" bit more costly in material, less
*exact* --if that ever matters-- in sizing, in being
pre-tied at some length vs. tied to fit, but quicker
in being pre-tied and needing no UNtying afterwards.

But, ... "multi-directional" ??!
1) How does this matter for slack-lining?
--where the direction is definite and invariable!

2) How is it really multi-directional at all?  If one
moves laterally, one slackens the near and
tightens the far bight, soon getting some sliding
around the object, on overcoming friction, but with
an introduced imbalance sustained by friction.

Perhaps you mean that it's variable in vertical
(or, more generally, "in parallel with a plane that
the object's in") movement, up'n'downwards here?
Here, too, though, it seems that there's not much
need of directional variance.


--dl*
====
« Last Edit: July 23, 2012, 09:10:07 PM by Dan_Lehman »

knot4u

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Regarding the tension, you can get to 1,000 pounds easier than you may think. The tension on the rope will be about half your body weight times the cotangent of the angle of the rope down from horizontal. In plain English, as your slack line dips less while you're on it (because you tightened the line a lot), the tension increases dramatically. The tension is a lot more than what seems obvious. Further, I was just talking about static loads there, not shock loads, which is absolutely a factor in slacklining.

Accordingly, I understand the point of a slack line is NOT to start with super high tension like a tight rope. That would be a rather hard thing to do, even with a trucker hitch. It would also be rather dangerous to have a super high resting tension. Anyway, tightroping is a different sport.
« Last Edit: July 24, 2012, 04:13:09 AM by knot4u »

agent_smith

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slacklines...hmmmm.

I looked at this from another angle from the point-of-view of giving advice.

If AffableAlligator had engaged my services (for a fee) and requested advice on how to setup a slackline, I would advise him not to use any knots within the actual slackline component.

I would advise: use 2 forged metal rings at each end termination of the slackline. I certainly would not advise anyone to use any form of knot - regardless of the properties of the knot - even if it was a bowline or a zeppelin derivative. The metal rings aka 'line-lockers' not only have no knots, but also grip and hold the tubular tape/webbing perfectly flat without any inherent twists.

As for the end termination anchors themselves, another recommendation is to use two 2 ton green WLL round 'crane' slings (used by doggers and riggers to sling loads). They are fairly cheap and no knots are required. However, even cheaper is to use common 25mm tubular tape/webbing and to tie a 'wrap 3-pull 2' anchor around a suitable tree or other anchorage point. Obviously the wrap 3-pull 2 knot has variations...eg you could go wrap 4-pull 2 or even wrap 5-pull 2...whatever.

Why anyone would consider tying a knot in the actual slackline material is beyond my ordinary reckoning. It defies logic. As stated, the metal ring 'line-lockers' induce no inherent twists in the slackline material. Furthermore, there are no knots. Its kind of like the concept behind the so-called 'tensionless hitch' - ie no knots.

Obviously, you need to acquire 2 forged metal rings - but, if you're planning to setup slacklines on a regular basis (like I do) it is a sensible investment.

On this occasion, I really cant see the point of providing Mr AffableAlligator with advice to the contrary. I would argue that if you advised him to tie a knot in his slackline material - you are giving him questionable advice.

Perhaps some of the posters in this forum should try an experiment - setup a slackline using metal forged rings, and then do it again using knots tied in the slackline. See which one is more efficient and keeps the slack line in an untwisted form. I might also tender that the metal rings (aka line-lockers) yield a higher MBS compared to any knot.

Mark
« Last Edit: July 24, 2012, 05:03:01 AM by agent_smith »

Dan_Lehman

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I looked at this from another angle from the point-of-view of giving advice.
//
 cheaper is to use common 25mm tubular tape/webbing and to tie a 'wrap 3-pull 2' anchor
around a suitable tree or other anchorage point.  Obviously the wrap 3-pull 2 knot has variations
...eg you could go wrap 4-pull 2 or even wrap 5-pull 2...whatever.

Why anyone would consider tying a knot in the actual slackline material is beyond my ordinary reckoning.
It defies logic. ...
I might also tender that the metal rings (aka line-lockers) yield a higher MBS compared to any knot.

Still you don't seem to want read (all) of what has been said!

Your positive advice (to use rings) is fine,
but your negative advice ("any knot will be welded") is wrong
--and mixing it with good advice doesn't lessen its harm,
insofar as knot knowledge goes.

Typical 1" (25mm) tubular nylon tape has a tensile strength
of about 4_000 pounds ; loading this to around 1_000 pounds
puts one at a not-so-terrible force for knots, even though they
will compress/wrinkle the webbing.  (I might observe that the
ring attachment can be implemented purely in the tape involved,
as a *new knot* --I've done such things for end-2-end and
eye knots : not getting the perfect rigidity & firm diameter
of metal, but ... they look promising (but remain untested, alas).)

And the "wrap-3-pull-2" advice is objected to precisely
(as stated above) because of its inconvenience in some
normal circumstances, vs. simply wrapping a pre-tied
anchor sling.


--dl*
====

agent_smith

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Dont need to read it because you are of course correct - in that not all knots will be welded/fused to the point where they cant be untied.

Yes, you can tie bowlines in your tape/webbing to form connective eye-loops. Or, you could tie zeppelin derived connective eye-loops.

My point is....why would you when more efficient/effective methods are available?

I will concede that if you didn't have access to forged metal rings, and you really wanted to setup a slackline in your back yard to entertain guests/kids, there is no law or rule to stop a person from tying bowlines in the slackline material. Its a free world.

I should have been more precise in the choice of my words...yes, one could tie bowline knots in tape/webbing and it wont weld/fuse.

I should have stated more clearly that from an advice point-of-view, my position is that one should state up front to an enquirer that forged metal rings (aka line-lockers) should be their first choice in creating connective end terminations. Among other things, these 'line-lockers' induce no twists and yield higher MBS in the tape/webbing material. This would be an issue if setting up a slackline across a void such as a deep canyon. Setting up a slackline on a beach (ie over sand) or in ones back-yard (ie over grass) has less risk and consequences in the event of material failure.

As for the discussion on the tried and tested 'wrap 3-pull 2' anchor - I stated that it is a 'multi-directional' anchor. It is 'multi-directional' - but only within certain limitations. Under load, a wrap 3-pull 2 anchor will provide an arc of around 90 degrees to work with. That is, the trajectory of force entering the wrap 3-pull 2 anchor could swing/shift 45 degrees left or right of the centre axis without consequence (even while under load). Thats quite a generous margin to work with.

What does this mean? It means that if you are stringing a slackline between 2 distant anchor points (eg 2 sturdy trees) the benefit of a 'wrap 3-pull 2' type anchorage is that it is self-aligning. Self-aligning anchors are particularly useful in all forms of rope work. I shouldn't need to point you toward well known American roping technicians such as Arnor Larsen and Reed Thorne....these guys have proven the merits of the wrap 3-pull 2 anchor in rescue work (among other things).

I fully acknowledge that a wrap 3-pull 2 anchor requires the user to tie "ABoK #1412" (aka tape knot or water knot) - and some may regard this as a PITA. I did point out that one could just as easily go a purchase a couple of green 2 ton WLL round slings (used by doggers/riggers to sling loads). I use green 2 ton round slings most of the time. If I have to walk a significant distance and carry loads of gear, I tend to use 25mm tube tape/webbing and install wrap 3-pull 2 anchors because it is very lightweight, very compact and very cheap.

To be honest, these days, I tend to try to work smarter, not harder - and so I 'cheat' and use an 'AZTEK' from Rock Exotica USA as a tensioning system. The AZTEK is simply clipped directly to the metal ring line-lockers (I orient the AZTEK in its 5:1 M.A. configuration). It all integrates nicely. I use 8mm high strength sterling cord (17.5kN MBS) in the AZTEK. Sterling USA manufacture some great cord/rope. As much as I sometime cringe around americans - I have to say that a lot of very good technology and innovation has come from North America. For instance, I also sometimes use the Vortex frame (yet another brilliant piece of American engineering) when setting up highlines or slacklines across voids/canyons. The Vortex frame enables me to create AHD's (artificial high directionals) to lift the ropes/tape/webbing off the ground.

If I'm setting up highlines (instead of slacklines) my preferred end termination anchorage is the so-called 'tensionless hitch' around sturdy trees. If I dont have access to a tree, then I'll employ 'Kootenay' type pulleys to simulate a tree radius so I can still tie 'tensionless' hitches. If I dont have access to Kootenays or trees, then I improvise with removable protection devices in rock (eg wired nuts, cams, pitons, etc) and build cordalette anchors. The interface between the anchorage and the 'tracklines' is normally tandem 8mm prusik hitches, rather than a connective eye-knot.

Mind you, walking on 25mm tape/webbing is certainly better than walking on twin rope tracklines :o I tried using rope as a 'slackline' many years ago just to see what the experience was like...it wasn't pretty.

Hope that clarifies and closes this thread?

Mark

Dan_Lehman

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[sans ANY reading]

Has it been tried : using a loop/sling of tape vs. single strand?

--could be a mess in keeping the strands back-to-back?
(possibly using adhesive tape as seizings --then a real "mess")

The "pro" would be halving the load per strand, and
halving the elongation w/load (something to mind in
tensioning, per Knot4U's et al's notes on forces).


--dl*
====

firebight

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Quote
As much as I sometime cringe around americans
So you don't like Americans, well that explains why you never answered my PM about the load release hitch.

BTW, I think the wrap 3 pull 2 is an excellent anchor, not sure I would use it for zipline or such, as I think a multi-point anchor would be better.