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I have two 4-ft x 4" x 4" wood posts, and each post has a screw eye. There's 12 feet of distance between each post.

How can I tighten a piece of 1/2" diameter rope that goes through each screw eye and it's stretched tightly without having to buy turnbuckles?

There has to be a knot just for this.

enter image description here

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    @TheEvilGreebo Would probably be answerable on The Great Outdoors.
    – David K
    Jul 30, 2018 at 17:11
  • How much tension are you wanting? Is your desire just to have the line taunt (e.g. not sag), or to have a certain force exerted on the posts through the screw eyes? If the latter, what are the specifications for the rope (i.e. is the force within the specs for a single run of the rope)?
    – Makyen
    Jul 30, 2018 at 17:30

4 Answers 4

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Use a simple cinch loop (a.k.a. trucker's hitch):

  1. Connect to the first eye and tie a small loop about 2/3 the way across the span.
  2. Run the tail through the second eye and back through the loop.
  3. Pull the tail toward the second eye to create the desired tension and pinch the tail to maintain position.
  4. Tie off the tail at the loop.

enter image description here

Source

The key here is the pulley effect, which compounds the user's strength, and the friction of the assembly, which helps hold position while tying.

Turnbuckles are a poor way to tighten rope. Most rope has far too much stretch for the range of adjustment a turnbuckle offers.

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    Once it settles under tension, this knot actually becomes a bowline -- it's topologically the same, it's just a matter of pulling the loop back through. I've used this to quickly throw a bowline on a sail.
    – keshlam
    Sep 13, 2023 at 14:30
  • Why edit an answer to a question that was closed 5 years ago as off topic, it just bumps it back up into the feed... Just curious.
    – matt.
    Sep 13, 2023 at 16:19
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    I'm more interested in site content quality than your feed. The question and the answer are still publicly visible. My edit integrated good information from a comment, which I've flagged for deletion.
    – isherwood
    Sep 13, 2023 at 17:03
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Tautline hitch is what we used in the Boy Scouts (also suggested by Ed Beale in comment above). Worked well, held when wet (with ordinary rope, including nylon; probably works with polypropylene too, but I've never tried). Does not work with monofilament, but you're not using that...

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Why not make your own "turnbuckle"? Instead of a single strand, connect the two screw eyes with a loop. Then insert a piece of scrap lumber and twist until the desired tension is achieved. You'll need a way to tie off the wood to keep it from untwisting.

As the rope stretches, it should be easy enough to re-tighten.

Granted, this will be more functional than attractive

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  • The first part is a really good idea. You could put a swivel in the middle of the span and twist the ropes on each side in opposite directions to tighten it up. Then you would need to just wire the swivel to keep it from spinning with respect to itself.
    – isherwood
    Jul 31, 2018 at 1:43
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Tight is not a very specific goal. A slackline with a tension of 200 daN would be a tight slack line, which seems like an oxymoron. If you are looking at achieving a tension just under what the 4x4s can handle, you might want to look at some slackline pulley kits. Most use webbbing, but many of the same principals apply to using rope.

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