Author Topic: Secure a line on a bight to a horizontal railing  (Read 1791 times)

Keystoner

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Secure a line on a bight to a horizontal railing
« on: April 24, 2017, 01:07:52 AM »
I'm looking for a good knot for this.

I work in construction as an inspector.  I see laborers rig it up all the time, but it's rarely pretty.

For example...before a bridge pier is poured, there is a deck and railing around the perimeter of the pier cap.  Sometimes tools are pulled up with a line.  The line is kept temporarily by tying it to the railing.  The knot is tied to the railing without access to either end of the line.  Generally there is no load on the line while it is tied (only when they're actually pulling up a tool or bucket, etc), but for purposes of my question, assume there is a vertical load on the line at least after tying the knot.

Sweeney

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Re: Secure a line on a bight to a horizontal railing
« Reply #1 on: April 24, 2017, 10:49:10 AM »
I suggest a midline loop (eg a butterfly) and toggle it in place with a snap on climbing carabiner. Quick and fairly idiot proof as long as nobody pinches the 'biner! A shackle would also work - just a bit more fiddly - through the loop and around the descending part of the line.

Sweeney
« Last Edit: April 24, 2017, 01:00:08 PM by Sweeney »

Keystoner

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Re: Secure a line on a bight to a horizontal railing
« Reply #2 on: April 24, 2017, 02:36:19 PM »
Thanks. That would work but it's not really an option in this particular application.

roo

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Re: Secure a line on a bight to a horizontal railing
« Reply #3 on: April 24, 2017, 05:36:52 PM »
I'm looking for a good knot for this.

I work in construction as an inspector.  I see laborers rig it up all the time, but it's rarely pretty.

For example...before a bridge pier is poured, there is a deck and railing around the perimeter of the pier cap.  Sometimes tools are pulled up with a line.  The line is kept temporarily by tying it to the railing.  The knot is tied to the railing without access to either end of the line.  Generally there is no load on the line while it is tied (only when they're actually pulling up a tool or bucket, etc), but for purposes of my question, assume there is a vertical load on the line at least after tying the knot.
A few options come to mind:

http://notableknotindex.webs.com/midspan.html
http://notableknotindex.webs.com/timberhitch.html (second diagram)
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Sweeney

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Re: Secure a line on a bight to a horizontal railing
« Reply #4 on: April 24, 2017, 05:53:02 PM »
A ground-line hitch tied using a bight of rope might be worth a try as well.

Sweeney

SS369

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Re: Secure a line on a bight to a horizontal railing
« Reply #5 on: April 25, 2017, 05:12:16 PM »
Hi Keystone and welcome.

During my personal work history, residential, commercial and industrial construction, I've always believed that simple is best.

Not for life support !

A simple round turn and two half hitches around the ratline (safety line surrounding the elevated work area) using the doubled rope or cord is sufficient and easy.
Just make sure that the tool to be hoisted is tied securely on the other end as well.

SS

Twine

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Re: Secure a line on a bight to a horizontal railing
« Reply #6 on: May 14, 2017, 03:03:56 PM »
Hello Keystoner,
I have for you a knot that is easy to make, easy to remember, its components are already well-known by most people, very (VERY) secure and still easy to untie.

It is called the "Folded-line Stoppered Clove Hitch". I just gave it that name.  ;D

1. Start by folding the line and tie an overhand knot on the doubled line. It will serve as a stopper knot.

2. Use the doubled line to tie a clove hitch to the railing.

3. Adjust ("dress") the hitch so the overhand knot gets pulled close to the half hitches that make up the clove hitch.

When you wish to untie it, insert your finger in the little loop and pull to loosen, then proceed as usual.

If you want the knot to be even easier to untie, you can use the groundline hitch as the base hitch, like Sweeney recommends, but it is my experience that it is more difficult to teach the groundline hitch than the clove hitch. No matter which one you pick, the overhand stopper knot makes a world of difference safety-wise.
« Last Edit: May 14, 2017, 03:31:01 PM by Twine »
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KC

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Re: Secure a line on a bight to a horizontal railing
« Reply #7 on: October 11, 2017, 11:32:15 AM »
For me, Round Turn + 2 Half Hitches (locker and keeper) is the basic benchmark hitch that all right angle hitches should be measured by!
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But, if making RT + 2HH; would seem easy enough to take extra tuck for Anchor +1 HH(keeper).
If in a bight or end in an eye; i actually like a carabiner as keeper position rather than HH.
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But, my next basic choice here would extend to taking the aforementioned Clove to it's sibling a 'Bag Knot', quite possibly 'Double Bagger' + keeper (HH or carabiner).
(Clove Family pictured with fave Bag)

This Crossed Turn start (i see as variant of RT) and Best Top Nip(in key equal/opposite SPart position) lock make this choice more secure;
and if all stops come from the crossing lock, and keeper doesn't deform SPart (just forms a failsafe, carabiner hangs loose around SPart)i'd think would be stronger on larger host mounts where size of  smaller host itself negates any added strength/host dictates strength/retained usable tensile against load.
Normally, (Slipped)Bag is one of my mult-purpose faves; especially how maintains on 'squareness'; it also functions backwards; but mechanically different force flow in reverse (to my eye).
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Though if grooming lacing for strength; would always start with Turn over host mount;
then 2-3 Turns around SPart (to form 'boot' or swelled 'grommet' at main breakpoint' of highest loaded deformity:where SPart enters the knot's inner workings ; then back over host and kinda back around and thru (will have to draw) to then lay next to SPart and make keeper to it. (in the spirit of ABoK#1669 :"The FIGURE-EIGHT HITCH and round turn. If the rope is weak and the hoist is heavy, a round turn on the standing part adds materially to the strength of the knot." but different finish).

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i think a single/simple Turn around SPart deforms it only; at it's most loaded part.
>>a Turn is like open hook, only hits 1 side of mount, takes a RT (Round/Real Turn) to make as full 'tang'(knife reference) as your eye says  it is!
But, more Turns help to mitigate the deformity and give 'strength' back.
A  single Turn pulls  concentrated at 1 point across linear axis of SPart length;
RT+ pulls more along SPart length at multiple points .
This is more notice-able when Dbl.RT around SPart, doesn't just slip down to seat against host mount;
but rather can 'float' or be set away from host mount (imparting some dynamics in line mechanism also);
to me showing can be alternate support leg for part of forces at some point.
Volume of force is finite, so any routing thru alternate; isn't carried on 'main' so much.
Friction hitch used around SPart for this with less than 15 degrees deflection to SPart and no deformities to SPart should be max(?) strength.
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