Author Topic: best way to tie rungs on rope ladder?  (Read 14681 times)

gever

  • New Member
  • *
  • Posts: 2
best way to tie rungs on rope ladder?
« on: January 02, 2009, 02:14:04 AM »
Hi Folks,
I'm experimenting with a rope ladder, and haven't worked out a way to tie the rungs into the ladder that is both secure and stable. It's difficult to find a knot or hitch that accepts a load on both the working and standing ends while connecting to a solid dowel (not drilled).

The things that make this problem interesting are:
- standing end can't be passed through a loop or bight (since it's coming from the previous rung)
- must stay tight when unloaded (the rungs are subjected to fairly dynamic loads)
- the standing and working ends need to depart from opposite sides of the rung

I've tried the simple Clove Hitch (had a tendency to come loose while the ladder is climbed), and the Rolling Hitch (which locks in nicely but the rung kind of hangs off the loaded line and flops around) and the Pile Hitch (both double and single, but it has a tendency to loosen when not loaded). In terms of having the rope come off opposite sides of the rungs, the Plank Sling has the right feeling, but it wants a continuous load or else it gets loose too. Surprisingly, the simple Slip Knot (with a large loop) has worked the best, but it also is only reliable under load.

I'm posting pictures of various attempts here:
http://flickr.com/photos/gevertulley/sets/72157612025804552/

Any thoughts?
    -gever
« Last Edit: January 02, 2009, 02:18:06 AM by gever »

Sweeney

  • Global Moderator
  • Sr. Member
  • *****
  • Posts: 975
Re: best way to tie rungs on rope ladder?
« Reply #1 on: January 02, 2009, 09:31:10 AM »
Have you tried fixed loops eg the Alpine Butterfly or Farmer's loop? The difficulty I can see is adjusting the loop to fit reasonably tightly around the dowel though neither should come loose as knots. It's interesting that you call this a rope ladder  - I was always taught that a rope ladder was made entirely of rope - wooden rungs make a pilot ladder. Not that this bit of nit picking helps you!

Barry

DerekSmith

  • IGKT Member
  • Sr. Member
  • *****
  • Posts: 1555
  • Knot Botherer
    • ALbion Alliance
Re: best way to tie rungs on rope ladder?
« Reply #2 on: January 02, 2009, 11:52:38 AM »
My immediate response would have been - Use a Constrictor - easy to tie 'in the run', exceptionally strong in inline tension and fully self holding (secure) - BUT in this situation the rungs are free to rotate and the Constrictor is not stable against rotational forces.

However, sticking with the Constrictor, there are two solutions--

First solution - tie one end of the rung with the constrictor on the face towards you and tie the other end with the constrictor on the rung face away from you.  Rotation of the rung would be countered by one Constrictor or the other.  This method is weak if the load is put near the  ends of the rungs, because then the rotational loading is concentrated on one knot.

Second solution - tie the rungs using constrictors, then go back along the rungs using a second run of cord and tie a second Constrictor but on the opposite face of the rung, so you finish up with one rope up the face and a second rope up the back of the rung.  This has the advantage of significantly increased safety by doubling up the number of ropes supporting the ladder while using a knot that is essentially free from weak spots.

If you don't already know it, use the quick fold method to make the Constrictors -

Hold the cord between finger and thumb in both hands, with the length that is to form the Constrictor between the hands, bring your hands together and with your right finger and thumb, roll your right thumb upwards to slightly twist the cord and help it form into a loop with the cord from your right hand on top of the cord in the left hand (i.e. nearer to you).  Slide your left thumb through the loop formed.  Take hold of the bottom of the loop with your right finger and thumb, lift the loop towards you, up, and over your left thumb, passing over the two cords already passing over the top of your left thumb and pass it over the end of your left thumb.  You will now have two loops around your thumb and on the top will be a completed Constrictor.  Pass the two loops over the rung and dress and set in place.

Derek

roo

  • Sr. Member
  • *****
  • Posts: 1874
    • The Notable Knot Index
Re: best way to tie rungs on rope ladder?
« Reply #3 on: January 02, 2009, 04:09:56 PM »

Any thoughts?
    -gever

Here are some options:

http://notableknotindex.webs.com/boaconstrictor.html

Preload as needed.  Rope and dowel type as well as dowel diameter will have significant impact on the results.  It'd be good to read the Ashley Book of Knots on this topic for other tips.
« Last Edit: October 28, 2009, 04:56:09 PM by roo »
If you wish to add a troll to your ignore list, click "Profile" then "Buddies/Ignore List".


SS369

  • Global Moderator
  • Sr. Member
  • *****
  • Posts: 1966
Re: best way to tie rungs on rope ladder?
« Reply #4 on: January 02, 2009, 06:47:38 PM »
Are we to assume that the type of rope is what was shown in the picture?

SS

Dan_Lehman

  • Sr. Member
  • *****
  • Posts: 4054
Re: best way to tie rungs on rope ladder?
« Reply #5 on: January 02, 2009, 08:20:55 PM »
I'm experimenting with a rope ladder, and haven't worked out a way to tie the rungs into the ladder that is both secure and stable.
t's difficult to find a knot or hitch that accepts a load on both the working and standing ends while connecting to a solid dowel (not drilled).

What size rope & dowels?  --diameters make a difference in my thinking . . .

Quote
The things that make this problem interesting are:
- standing end can't be passed through a loop or bight (since it's coming from the previous rung)
Why not the working end, then?
--although I too am moved to find a TIB knot solution to this rope problem.

Quote
- must stay tight when unloaded (the rungs are subjected to fairly dynamic loads)
- the standing and working ends need to depart from opposite sides of the rung
Why?
Conceivably, the departures would be on one side, and thereby provide some kind
of *bumper* effect in protecting a surface from dowels banging into them.  But in any
case, I don't see this as critical, though maybe desirable.

Quote
I've tried the simple Clove Hitch (had a tendency to come loose while the ladder is climbed),
Then how about adding a 3rd HH?
Or back-2-back Cow Hitches, which might tighten better.
Quote
Surprisingly, the simple Slip Knot (with a large loop) has worked the best, but it also is only reliable under load.
This also is in my thinking.  You might be able to do something with that slip bight
(just tried making a Clove in it, but that didn't look good).

(I have one answer, if material dimensions allow; by the look of the in-effect
"Rope Ladder" shown on you site, they do!  Describing this hitch might be
more challenge, but ... .  -- #20090102f13:35 , the new year's first for me)

 :)

gever

  • New Member
  • *
  • Posts: 2
Re: best way to tie rungs on rope ladder?
« Reply #6 on: January 02, 2009, 09:47:33 PM »
Thanks for all the help, folks.

Some simple experiments with the opposing constrictors as proposed by Derek Smith show that to be a viable solution. When the rain stops I'll try it in the tree and see how it holds up to being climbed. Now to figure out how to diagram it so that kids can understand it.

Special thanks to Roo for pointing out the TIB solution he points to on his Constrictor page, that turned out to be simpler than the folded loop technique.

Dan_Lehman

  • Sr. Member
  • *****
  • Posts: 4054
Re: best way to tie rungs on rope ladder?
« Reply #7 on: January 04, 2009, 03:16:49 AM »
Here's a simple solution to both the Clove-Hitch-coming-loose and the
Clove/Constrictor-rotational-loading problems in  one fell soup:

working UPwards (at least said here, for sake of orientation & description),
tie a Clove Hitch;
then cast a reverse-oriented Half-hitch to continue upwards.

.:.  The weighted rung will bear into a Cow Hitch-like structure (Cow with
end HH'd, essentially), which doesn't rotate; the trio of HHitches should
suffice to keep themselves collectively secure.

Reflecting briefly upon this, I think that it works pretty easily--re tying,
to set rungs at desired positions--if tying DOWNwards, making the
Cow/Girth hitch, and adjusting for desired span to rung above,
and then casting a closing HH to form a Clove in consideration
with the HH adjacent, and leading down to the next rung.

The same structure works with the enhanced-security Clove, viz.,
the Constrictor; but I think that this is superfluous for security, and
it's more tricky to tie:  one would form a turn, then cast on a TIB
Constrictor appropriately oriented to render the desired Cow/Girth
structure for the upwards-departing end.

--dl*
====