Author Topic: Knot for fixing a long rope (from the middle) to a long pole (in the middle)???  (Read 10662 times)

kuskoli

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I am wondering how to tie a long rope from the middle to a long pole. I.e. the rope is so long that it is either impossible or impractical to pass the end of the rope through the loops etc... On the other it is impossible to put the "rope loop" around the pole (too long).

I cannot be the first one wondering this so that there must be a knot(/s) for it, jut haven't been able to find...

br
kuskoli

xarax

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   Try a slipped double-line Pile hitch.
   http://igkt.net/sm/index.php?topic=4892.msg32040#msg32040
This is not a knot.

Tex

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The lesson here is you can always make an "end" in the middle of a rope by folding the rope at some point.  My first instinct would be to not only fold it, but knot it, ie tie a long loop.  This avoids some force pulling your double line apart.  Then you can tie whatever normal knot you want with the doubled loop lines.  This thing xarax shows seems to cleverly take advantage of having the extra line, but you could also tie a clove hitch, or constrictor, or whatever.

roo

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I am wondering how to tie a long rope from the middle to a long pole. I.e. the rope is so long that it is either impossible or impractical to pass the end of the rope through the loops etc... On the other it is impossible to put the "rope loop" around the pole (too long).

I cannot be the first one wondering this so that there must be a knot(/s) for it, jut haven't been able to find...

br
kuskoli
Give these a try:
http://notableknotindex.webs.com/midspan.html (middle diagram)
http://notableknotindex.webs.com/timberhitch.html (second diagram)
If you wish to add a troll to your ignore list, click "Profile" then "Buddies/Ignore List".


Dan_Lehman

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I am wondering how to tie a long rope from the middle to a long pole.
I.e. the rope is so long that it is either impossible or impractical
to pass the end of the rope through the loops etc...
On the other it is impossible to put the "rope loop" around the pole (too long).
Your query leaves it unstated what the purpose
of the attachment is,
what the size(s) of the tied-to object (pole) is (diameter)
relative to the cordage,
and how the tied-off structure will be loaded.

E.g.,
Quote
The lesson here is you can always make an "end" in the middle of a rope
by folding the rope at some point.  Then you can tie whatever normal knot
you want with the doubled loop lines.
(My first instinct would be to not only fold it, but knot it, ie tie a long loop.
This avoids some force pulling your double line apart.)
This tactic almost implies that the loading will be from
only one end/side of "middle" and not both,
or not both simultaneously --"almost", for the parenthesis
includes some awareness of awkward forces if the loading
is otherwise.

What knots have been suggested above are not so
great for all-sides loading --esp. X's, which slips undone
from the one end.

For accommodating loading from both sides,
and doing so without having the hitch rotated
against the pole to adjust to the new loading
(if loading changes from one to the other side,
that is),
I'd start by making a big "Z" ("S") of the middle
against the pole --this structure giving one two
bights to then work around the pole and tie off,
effecting hitches that are properly end hitches
from either direction.  And for this, a simple
overhand noose which Xarax has called "the
buntline killer" (IIRC) works pretty well.

Still, the exact circumstance of materials --that
diameter of pole vs. of cordage-- can point us in
one direction or another.

Cheers,
--dl*
====

kuskoli

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Quote
Your query leaves it unstated what the purpose
of the attachment is,
what the size(s) of the tied-to object (pole) is (diameter)
relative to the cordage,
and how the tied-off structure will be loaded.

I have run to the problem a few times, last one (today) when securing scaffoldings. I.e.:

Rope coming and leaving more or less opposite directions.
Pole is solid, diameter 10-15 cm (4-6 inches).
Not necessarily constant load, more like sudden / abrupt (hopefully no load!).

Quote
The lesson here is you can always make an "end" in the middle of a rope
by folding the rope at some point.

I presume I must make an "end" by folding the rope, but how to make it so that it holds...

Of course one way is to have a short rope (e.g. 0.5m) and use it to secure the knot. It just isn't so elegant...

I need to check and try the "slipped double-line Pile hitch"-

br
kuskoli

Tex

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Updated:I realize now this is a thread about protecting life. This post here is just about knots. My next post is about the real practical issue

DL no, I didn't address all possible loadings but I don't know why you think I (or xarax) overlooked them either.  As you say, his question didn't specify.  My knot in the line was just generic guard against end to end loading doing something that might not normally happen with whatever knot is tied.  That wont' always be bad, but it will be different. Once you have that, you can tie any knot you would normally tie for the reasons you would normally tie it.  It could be that there are knots that will still behave differently with two ropes than with one, but I guess most will still work similar to how they usually do.

After that end to end loading itself is unlikely to be the problem.  Once I've made my one rope all forces are as a SINGLE net force coming through that one rope from one direction.  Sure that can change this way or that as the two attached ends pull this way or that.  But even if we only had one rope to start with, that could be true.  The rope might move and get tugged from here and then from there. One vector is one vector.  If it is the sum of two or not, doesn't change anything once we have my knot.  The question though was how to deal with the middle of the rope issue, not how to tie a rope to a pole. There are tons of threads on that and what my answer I think does, is reduce this question, again, from

"How do I tie the middle of a rope to a pole?"  to "How do I tie a rope to a pole?"

Of course the answer to that is "it depends."   

Actually though the question did say that the reason we're using the middle of the rope is because the rope is too long to go get the end.  This to me implies one end loading, not that it matters in my partial solution.

So DL, how DO you tie a rope a to a pole? 

(It does seem at least that the word "to" implies different knots than "around", hmm...)
« Last Edit: July 23, 2015, 04:46:32 AM by Tex »

Tex

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Anyway...

It sounds to me kuskoli like you're  talking about a rope to catch a human falling to prevent death or injury. (or maybe to prevent things from falling, things which could land on a human)

Obviously I take no responsibility for advice on that. If it were me, I'd start by finding out what the tried and true systems are (preferably through professional training) and only make changes from that if I was very sure I knew what I was doing.  I'm pretty sure if it's a person attached you'd want dynamic rope, or some one-time-use energy absorption, but I'm no climber.  Even a small fall can be a big fall factor, but I guess there must some fall distance small enough where your body is dynamic enough. (obviously 2 inches for example is ok even if the fall factor is 2).  Doesn't OSHA have some standards on this stuff?  Isn't there gear similar to via ferratta gear that's designed for this stuff?

I guess the climbers and such can weigh in. 

What I can definitely say is don't even think about that timber hitch for someone's life. 
« Last Edit: July 23, 2015, 04:48:50 AM by Tex »

kuskoli

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[quote author]
Anyway...

It sounds to me kuskoli like you're  talking about a rope to catch a human falling to prevent death or injury. (or maybe to prevent things from falling, things which could land on a human)
[/quote]

Hmm, lets say prevent injury or damage. I have a fairly big old house and try to do as much as possible of the repairs etc by myself.
Lets put it this way: I am looking forward to find simpler and more practical ways to do things safely.

Dynamic rope or not? IMHO depends on case... I have done little mountaineering and have a good dynamic rope.

Quote
What I can definitely say is don't even think about that timber hitch for someone's life.

Not solely, but perhaps with that "non-elegant" short piece of rope to safe it...

br k

Z

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Give these a try:
http://notableknotindex.webs.com/midspan.html (middle diagram)
http://notableknotindex.webs.com/timberhitch.html (second diagram)

I'd try these.

Also, this is sacrilege, but if you have carabiners to use on the rope, then there are some other appealing options.
If you're reading this, it's too late.

Dan_Lehman

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Quote
Your query leaves it unstated what the purpose
of the attachment is,
what the size(s) of the tied-to object (pole) is (diameter)
relative to the cordage,
and how the tied-off structure will be loaded.

I have run to the problem a few times, last one (today) when securing scaffoldings. I.e.:

Rope coming and leaving more or less opposite directions.
Pole is solid, diameter 10-15 cm (4-6 inches).
Not necessarily constant load, more like sudden / abrupt (hopefully no load!).
You left unstated --explicitly-- what the loading
will be : from BOTH ends at once or variously,
or from just one end (and you know which)
but the issue is of tying off in the middle.

Tex's point of making a bight and then tying <whatever>
is a simple solution to the "just one end" loading,
as one can anticipate that loading in positioning
the knot so it won't rotate.
E.g., looking down at pole cross-section to make it
into a clock and you bring rope in at 6:00 and tie
off, with loading coming from 9:00 or else nearly
opposite, 3:00, there will be force trying to move
the knot left- or right-wards.
My sketch above gives fixed knots at both 9/6 and
no movement.



Quote
I presume I must make an "end" by folding the rope,
but how to make it so that it holds...
Why, you simply tie off this folded end (a "bight")
by whatever knot you would've used had the end
been a single strand --you now work with a doubled
strand, that's all.

Quote
Of course one way is to have a short rope (e.g. 0.5m) and use it to secure the knot. It just isn't so elegant...
Maybe your best solution --YMMV.  It is a good
point, and probably the most flexible; but you
might not need to go to this extent in materials.

Quote
I need to check and try the "slipped double-line Pile hitch"-
Only if you know --as I discussed above-- that you
will be loading only THIS end (as that knot slips
undone when loading one end, holds for other end).
Don't scare me!


--dl*
====

Dan_Lehman

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DL no, I didn't address all possible loadings
but I don't know why you think I (or xarax) overlooked them either.
Because --as I did state (so you should know!?)--
your general solution leads to knots that suffer
from *in*directness vis-a-vis some of the loadings
(or any, if starting at my "6:00" in-between point),
and X's --as should be obvious-- SLIPS UNDONE
when pulled by one of its ends !!  Goodness, is this
not obvious?!   ???

Quote
So DL, how DO you tie a rope a to a pole? 
As though I DO !
But I gave my solution above.
In the general sense of your advice,
one makes the "Z" fold to produce TWO
bights
(of the 'Z' these are at the upper-right
 & lower left of the letter-like schematic)
and then proceeds with each for each of
the two loadings vs each end.
(Upper-R bight swings around to tie off to
upper Left single strand,
 and complementarily for the lower side.)

(And I came to see that the connecting
strand between these bights
 --the slash part of the 'Z'--
really doesn't make a good component for the
knotting, and should be seen as just a tail
coming along for the ride.)


--dl*
====

Tex

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DL I think by your re-rephrasing of my instructions, that you are missing my point a little.

I am not talking about simply folding a bight and tying whatever with it.

I'm talking about tying a long loop knot to form a folded bight where the fold is joined at one point away from the end of it.

At that point all force on the folded bight always comes from the loop knot, from whatever one direction it pulls from.

Of course there are still two rope ends attached to the other side of that loop knot fighting (possibly) to pull it here or there, but at any one time they create a single net force pulling up the folded bight in a single direction.   If that bight is then tied with whatever, those two forces are not trying to pry whatever apart.  The whatever still sees only a single force down a single doubled line.

Can the direction of that force change?  Sure.  That can be true regardless if there are two things fighting to control that direction.  Ropes move.  Directions can change. If you want a knot resistant to movement, then of course "whatever" has to be that kind of knot.

As it turns out, he's falling on this thing.  It's going to be stressed from one end in one predictable direction, and rotation of the knot a little probably isn't a big concern anyway.

I was just thinking about going with the standard trusted double 8 here, but I know people are going to throw a fit about to dress it with 4 segments going through it to get the max possible tonnage of holding power.  It would be a massive knot though and use a ton of rope.






Tex

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oh.. it is worth pointing out that the usual criticism of the double 8 doesn't hold here.  Jamming shouldn't be a concern at all.  This isn't sport.  The hope, as stated, is that the knot NEVER ends up loaded. 

Dan_Lehman

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DL I think by your re-rephrasing of my instructions, that you are missing my point a little.

I am not talking about simply folding a bight and tying whatever with it.
But why not?
Anyway, this IS a good point to make;
that circumstances might demand more,
okay, fine --but for starters, bight-qua-end
is worth realizing/understanding.

Quote
I'm talking about tying a long loop knot to form a folded bight where the fold is joined at one point away from the end of it.

At that point all force on the folded bight always comes from the loop knot, from whatever one direction it pulls from.

Of course there are still two rope ends attached to the other side of that loop knot fighting (possibly) to pull it here or there, but at any one time they create a single net force pulling up the folded bight in a single direction
.
It's not just question of knot integrity given
different directions of loading (possibly simul-
taneously), but of that effect on the wrapping
around the pole
--of jerking the structure from
one orientation into another.

My "Z" splits the work into the two bights,
each of which deals with one direction, one end.

Now, in the foggy circumstance of some tying off
for fall protection, I guess it might be known that
one will only load in one direction and ... we can
even skip the forming of an eye knot --though
we might still prefer that, I guess.


--dl*
====



If that bight is then tied with whatever, those two forces are not trying to pry whatever apart.  The whatever still sees only a single force down a single doubled line.

Can the direction of that force change?  Sure.  That can be true regardless if there are two things fighting to control that direction.  Ropes move.  Directions can change. If you want a knot resistant to movement, then of course "whatever" has to be that kind of knot.

As it turns out, he's falling on this thing.  It's going to be stressed from one end in one predictable direction, and rotation of the knot a little probably isn't a big concern anyway.

I was just thinking about going with the standard trusted double 8 here, but I know people are going to throw a fit about to dress it with 4 segments going through it to get the max possible tonnage of holding power.  It would be a massive knot though and use a ton of rope.
[/quote]