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Backyard zipline

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  • Aug 10th, 2021 2:37 pm
[OP]
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Dec 6, 2006
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Toronto

Backyard zipline

Anyone has or try zipline in backyard? What's your setup and experience?

Been thinking of setting up one. First thought from a while ago, rather straight forward to support 150lb person or so, likely between deck and a tree.
But now looking into it more and recalling some grade10 physics, it's not that simple. Depending on line length and sag, rough estimate on my case would need tension (ie. lateral pull) around 10x the person's weight on each end. So attaching to deck is definitely off limit. Will need a beefy post, stacking 2-3 2x12 perhaps. Saw a vid doing that. Still doable but certainly more involved, more money and more wife complains.
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Jan 25, 2007
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Paris
My friend did a small kids one. I think you really need mature trees, or a big post mounted deep with support wires in the opposite direction.
I have 2 6x6s (one at each end) for a clothesline, and over time the tension of the clothesline has warped the less supported 6x6 post.
[OP]
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Dec 6, 2006
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Jerico wrote: My friend did a small kids one. I think you really need mature trees, or a big post mounted deep with support wires in the opposite direction.
I have 2 6x6s (one at each end) for a clothesline, and over time the tension of the clothesline has warped the less supported 6x6 post.
Indeed. wouldn't think a cloth line can warp a 6x6, but the tension force is just that much.

Is there some sort of chart to show what lumber size can support what cantilever weight? Can't find one yet...
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Oct 11, 2012
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Sounds like fun but wouldn’t there be some kind of insurance issue?
[OP]
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AllenWayne wrote: Sounds like fun but wouldn’t there be some kind of insurance issue?
That's a small secondary reason to not attach to deck. Other than that I haven't came up with other insurance concern.

Would there be any additional insurance issue compare to other backyard play structures? Eg the Costco climbing dome which is 5' high, or playset with slide and swing which usually has 5' high platform. Don't plan on having rhe slipeline rider foot height more than 5' high at the highest point.
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Jan 16, 2011
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boyohboy wrote: That's a small secondary reason to not attach to deck. Other than that I haven't came up with other insurance concern.

Would there be any additional insurance issue compare to other backyard play structures? Eg the Costco climbing dome which is 5' high, or playset with slide and swing which usually has 5' high platform. Don't plan on having rhe slipeline rider foot height more than 5' high at the highest point.
Is your backyard fully fenced in? How close are your neighbours?
[OP]
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kr0zet wrote: Is your backyard fully fenced in? How close are your neighbours?
Yeah fully fenced. Decent size yard so neighbours not that close in distance.

The slipeline trolley/seat is usually attached with bucket removable when not in use anyway.
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boyohboy wrote: Yeah fully fenced. Decent size yard so neighbours not that close in distance.

The slipeline trolley/seat is usually attached with bucket removable when not in use anyway.
If that's the case I don't know what insurance concerns there would be... Your own kids would be using it and when not in use the seat would be removed and neighbourhood kids cant roam your back yard.
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Nov 24, 2015
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boyohboy wrote: Indeed. wouldn't think a cloth line can warp a 6x6, but the tension force is just that much.

Is there some sort of chart to show what lumber size can support what cantilever weight? Can't find one yet...
Friends dad set one up between a tree and a 2 level bunky/shed structure. The damn shed would lean a bit when some people used the line and it was a solid structure!
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Oct 9, 2010
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Do you care about how it looks?

I lived in Whistler, and their ziplines all were attached to trees, but the trees were supported at the other side with substantial cables (like a telephone pole is supported). Some of those lines were crazy long though, and I think the weight limit was 250lbs (maybe 275).

You could replicate this with posts made of something that won't buckle under compression (a wood pole, or largeish diameter steel pole), then just anchor the cable to "something". If you're lucky, you have an enormous rock you can drill an anchor into, or you can dig a giant hole and just fill it with cement, then install an anchor. You can also attach the cable to the lower part of the tree, so it'll be far less likely to get yanked over.

Depending on the length of the line, the tension could be significant. And depending on the line's tolerance for sag (how high off the ground it is in the middle), that can reduce the tension you require. It should be a pretty easy triangle based off the distance to the middle of the cable. You also want a pretty good safety factor on the cable; if that thing snapped, that is a realistically lethal amount of tension.
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Jan 25, 2007
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Paris
boyohboy wrote: Indeed. wouldn't think a cloth line can warp a 6x6, but the tension force is just that much.

Is there some sort of chart to show what lumber size can support what cantilever weight? Can't find one yet...
Well, the wife wanted it cranked fairly tight, it’s over 50 feet in one direction, and over time the wood is subjected to hot, cold, wet and dry so it slowly started to banana towards the house.
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ChubChub wrote: Do you care about how it looks?

I lived in Whistler, and their ziplines all were attached to trees, but the trees were supported at the other side with substantial cables (like a telephone pole is supported). Some of those lines were crazy long though, and I think the weight limit was 250lbs (maybe 275).

You could replicate this with posts made of something that won't buckle under compression (a wood pole, or largeish diameter steel pole), then just anchor the cable to "something". If you're lucky, you have an enormous rock you can drill an anchor into, or you can dig a giant hole and just fill it with cement, then install an anchor. You can also attach the cable to the lower part of the tree, so it'll be far less likely to get yanked over.

Depending on the length of the line, the tension could be significant. And depending on the line's tolerance for sag (how high off the ground it is in the middle), that can reduce the tension you require. It should be a pretty easy triangle based off the distance to the middle of the cable. You also want a pretty good safety factor on the cable; if that thing snapped, that is a realistically lethal amount of tension.
I have some trees but obviously not all suitable, and no way connect without obstacles in between. So for sure I'll need to install a pole/post for 1 end.
- First option, one corner has 3 tall trees about 10ft apart but they are bit under-sized each on their own, only about 8" diameter... but perhaps can support each other. i.e. connect zipline to the furthest tree, and build A-frame (diagonal frame) down to ground of tree in front to add support. Other end will need a new post, near the deck. Following this direction will allow about 65' of open zipline distance
- Second option, another corner has giant maple which def good for attaching zipline. Other end will need new post, about 90' away. Cons is however there's deck stairs and a tall lilac tree being rather close to the zipline path. So will have to cut down the lilac tree to be safer... it's kinda grew ugly in form anyway but yeah. So perhaps good to have a "reason" to cut it down and may actually looks better without it. I feel like this 2nd option will look better overall (vs first option where having an end post next to deck).

New post will have to be 4' hole in ground with poured concrete and re-bar I guess, at minimum.
What to use as the post however.... 2-3 ply 2x12, or metal pole. Lumber def easier to work with. Not sure where to buy metal pole frankly.

Still can't find any ready-made chart for what size lumber can support what cantilever weight. Tho there's formula to calculate max deflection (bend), and there's "code" allowable deflection on cantilever beam, so I should be able to calculate the supported weight. But not sure which code allowed deflection rating would be more applicable, I've seen ranges from L/90 to L/360...
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Seems like a lot of engineering and effort for something that probably won't get much use once the initial thrill wears off.
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Chickinvic wrote: Seems like a lot of engineering and effort for something that probably won't get much use once the initial thrill wears off.
Possibly. I guess with kid's playthings, there's always that possibility.
Though I'd hope much more than one use, perhaps can last a few years of interests on and off. It's kinda once in a lifetime thing, won't know until I actually do it.

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