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Zip line anchoring help

  1. Mar 15, 2017 #1
    So I'm making an ~200ft long zip line with the top being anchored to a tall tree in my backyard. My problem is I need an anchor for the bottom. Can I use a 6"x6"x12' plywood buried 4 feet in the ground with a guy wire anchored to a 4"x4"x4' 2.5 feet into the ground? What would you say I should use to anchor th zip line about 4-7 feet off of the ground? Note: I can't find any used telephone poles near me so you have to come up with something else besides a telephone poll.
  2. jcsd
  3. Mar 15, 2017 #2

    Vanadium 50

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    Isn't a telephone poll when someone calls you up and asks you what you think about how well the mayor is doing?

    Considering that this is safety-related, I would hire an actual engineer and not go looking for what a bunch of folks on the internet say.
  4. Mar 15, 2017 #3


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    Welcome to PF. Thanks for the question. Sorry about the reception you received.
    I had never heard of it being called a zip line before so I had to look it up.

    Anyhow, the folks here at PF are highly averse to doing anything that might come back at them if someone got hurt. There are other sites, frequented by members who have less competency that will happily help you solve the problem of providing a good solid anchor.
  5. Mar 15, 2017 #4


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    The wire support should be an 'A' frame so it does not fall sideways, but more importantly, if someone goes to far they do not hit the post.

    A good design would be to keep wood away from the soil. Over time, wood will rot in soil. You will not be able to inspect a buried anchor so when it fails, it will fail suddenly without warning.

    The ground anchor will come down to a number of things. What is the soil type? How deep is the soil, does it have many rocks?

    The strength of the anchor must be enough to handle the maximum tension in the wire. Sag will be very important because it reduces the wire tension, but the tension in the wire will always be more than the rider. The straighter the wire the more tension will be produced by the weight of a rider as is demonstrated by the “Triangle of forces”. https://en.wikipedia.org/wiki/Lami's_theorem
  6. Mar 15, 2017 #5


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    Agreed. Please try to find a competent local person who can help you with this. And be sure to let your homeowner's insurance company know about the new toy and who-all will be using it. They may have some suggestions about how to make it as safe as possible. Keep in mind that entertainment companies who operate Zip Lines carry liability insurance.
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