Zip line connection to a backyard play set: need advice

[Ole Anderson]

Just remember the old adage about using cable clamps: "never saddle a dead horse". In other words the saddle portion of the clamps should be on the long "live" tension portion of the cable with the U-bolt pressing on the "dead" tail. And protect the tree from the cable either with wood blocking or by running a thru closed eye bolt.

[Roger Feeley]

Just remember the old adage about using cable clamps: "never saddle a dead horse". In other words the saddle portion of the clamps should be on the long "live" tension portion of the cable with the U-bolt pressing on the "dead" tail. And protect the tree from the cable either with wood blocking or by running a thru closed eye bolt.

I did the blocking. I didn’t wat the cable to slip so made dados in the blocks. The cable doesn’t touch the tree.

I will have to look at the clamps. I didn’t know there was a right way. Thanks.

[Charlie Velasquez]

Thanks Malcom,
I found a calculator that seems to do the math for me.
https://www.ropelab.com.au/highline-tension-calculator/
The amount of sag seems to be a big deal. If I have 12” of sag, the force on each end isn’t that different from the weight of the boy. I put in 1” and it went up to ten times the weight.

Check your numbers. When I coached and officiated volleyball in the '80's the rules committee changed the allowable sag from 3" to 2". High schools were blowing out their floor plates.

I think you mixed your units, using feet for distance and inches for sag.
Using your calculator and 480" (40') for span and 1" for sag on a 40 pound load I get 4800 pounds at each anchor.
At 12" sag I get 400 pounds

To get it to about 40 pound tension at each anchor you need almost a twelve foot sag.