Concerned about zipline killing trees

[pao1001]

Hello everyone,
I built a DIY backyard zip line, and it goes across my pool. I know about the cambium layer in the tree, and I am a bit concerned about killing my 11.5-inch diameter oak trees. The zip line is wrapped around them, and it is 1/8 inch galvanized cable. I cut a section of garden hose to go around the section of cable touching the tree. Is this enough to keep the trees healthy, or do I need to buy the real tree saver? I am reluctant to buy the real tree savers as they are $60.
Thanks,
Paolo

 

[Scratch]

You can make your own zipline tree savers out of 2x4's and a cam strap. Check out this link, they mention a DIY option in the description:

Tree Saver Block Kit | Protect Trees, Anchor Zip Lines

Our Tree Saver Blocks act as spacers between your tree and cable to reduce bark pressure. Easy to secure with cam straps. Save your trees—set up smart.

www.ziplinegear.com

 

[evo]

Do it right or don't do it.

 

[colb]

A very big lag bolt can be adjusted each year...

 

[TreeCo]

I think you'll be fine but you should move the anchor up or down the trunk a few times per year.

 

[Jonny]

Cable looks awful skinny. Like it won't take long to cut through that hose. Any idea what it's rated for? Idk much about ziplines, but I imagine they see some degree of dynamic loading.
I also realize that has nothing to do with your question, but maybe worth considering anyways.

 

[climbstihl]

How long is your Zipline?
I work at an aerial park, we have quite a few ziplines, our longest being 530' long. We use compacted steel cable, which is much smoother for a better ride and less wear.
I believe we use 12mm, but I think 10mm would be enough for a backyard zipline.

Excerpt from the IAPA Training manual for Instructors, Rescuers and Toprope Belayers

 

[climbstihl]

Forgot to tell you how we attach to the tree. We use wide crane type slings, which are not rated for PPE or life support, but are more than strong enough, plus it is backed up by a steel cable going around the tree, which is slack.

 

[Scratch]

I have a 150' zipline made from 3/8" steel cable. It goes over a 45' deep ravine on my backyard. Thats why I'm building a rope bridge in another thread. It's about a 150 yard uphill walk to get back to the start. I did a lot of research and found ziplinegear.com to have some very helpful info when it comes to installation, cable stretch, angles, etc. I use their tree saver idea but used 2x4's instead.

I was surprised to hear Climbstihl's info about aerial parks using straps to secure to trees, but then I remembered I used the same method on a trolley system for a moving target setup on my gun range for years, and when I took it down last year, there was no noticeable marks at all on the trees. I may have to switch to that in the future as I think the trees will start to grow around my 2x4 blocks eventually.
Here's my zipline:

 

[GregManning]

I agree with some of the above points, only stronger.

A) 1/8" cable sounds way too small. I can envision some dynamic loading situations.

B) 1/8" cable under load WILL CUT THRU that hose in a surprisingly short time.
Most of the load will be along a single line of the cable, not the whole 1/8" diameter.
The hose material (vinyl/rubber,etc) will "cold flow" under those kind of loads / pressures.

C) Do it right.

D) Liability for guests, neighbors, etc. ?

 

[southsoundtree]

How much money for a compromised 11.5" oak?

I'd use wood blocking, 2x2", 1x1", give or take.

 

[climbstihl]

Here's our setup.