Anybody here built a zip line?

[Dargo]

My wife has been on to me about getting a zip line built that I talked about building a few years ago. She pretty well wants 2 lines. One that goes across my lake and terminates on the island in my lake. People can either ride it to the island or drop off into the lake. The other would just be a longer one running a few hundred feet across a wooded part of my property.

If you've built one, where is a good place for me to buy the trolley that rides on the line and a harness? We did a lot of zip lining in Costa Rica last year. That renewed her requests for me to get going on ours. I was frankly shocked at how small some of the cables were in Costa Rica that spanned 600 or 700 feet over deep ravines. Just guessing, I'd say they are only 3/8". Does that sound right?

 

[DocHeb]

With the zip lines in Costa Rica - how do they get the trolley back to the start?

The strength of 3/8" cable is nothing to sneeze at - Galvanized Steel, 7x19 aircraft cable has a breaking strength of 14400 pounds, more than enough for even American tourists.

This Site sells tandem trolleys (breaking weight 14000 lbs) for Zip Lines with 3/8" to 1/2" cable.

 

[Willl]

Did one many, many years ago with an upside down bicycle forks and wheel sans the tube and tire.

We were brave souls back then, no way would I trust that same setup today.

I see some of todays setups run 2 cables with a trolly that has 2 wheels.

 

[Dargo]

Thanks for the info and link. The trolleys we used looked like the listed "heavy duty" models. As you mentioned, they too have a breaking weight of 14,000 pounds. I suppose even the biggest American tourist has a better chance of uprooting a tree than breaking the trolley or cable. I am sort of shocked at how expensive the cable is though. Even though 1/4" would most likely work, I'd feel better going with the 3/8" like I have been on.

Rather than using trees, I'll be using buried I beams for anchor points on each end. Well, I may use a huge oak tree for the top side on one zip line. That way I wouldn't have to build as much of a platform from scratch and I wouldn't need to use such a large I beam.

 

[MossRoad]

Thanks for the info and link. The trolleys we used looked like the listed "heavy duty" models. As you mentioned, they too have a breaking weight of 14,000 pounds. I suppose even the biggest American tourist has a better chance of uprooting a tree than breaking the trolley or cable. I am sort of shocked at how expensive the cable is though. Even though 1/4" would most likely work, I'd feel better going with the 3/8" like I have been on.

Rather than using trees, I'll be using buried I beams for anchor points on each end. Well, I may use a huge oak tree for the top side on one zip line. That way I wouldn't have to build as much of a platform from scratch and I wouldn't need to use such a large I beam.

Wow! Sounds like a neat project.

Just remember that large oaks are often hollow on the lower end.

 

[carpenter383]

My jeep winch is rated to pull 12,000lbs, and it has a 3/8 cable. Smaller winches in the 8,00lb range have 5/16 cable. I'm sure the braking strength of the cable is higher than the winch will pull. But this may give you more of an idea about cable strenth.
Also I'm sure there is good cable and cheap cable so the quality of the cable your using will be something to look at.
You could look on ebay and see how much replacment winch cables are going for. I bet a good 5/16 cable would be more than strong enough.

 

[MossRoad]

... the quality of the cable your using will be something to look at.
...

Why don't you check out the prices of cable at Harbor Freight?

Hmmm.... maybe not. You can put down a cheap tool and walk away from it. A cheap zip line, on the other hand....

 

[/pine]

I have been considering one for several years as a way to cross the river here...I have so many other "works in progress" I have not gotten to it yet...

I think I would want something like a bosun's chair and a secondary line to pull yourself across and back...keeping the cable level and use a landing platform on either side...

 

[kevindsingleton]

Why don't you check out the prices of cable at Harbor Freight?

Hmmm.... maybe not. You can put down a cheap tool and walk away from it. A cheap zip line, on the other hand....

Where do you suppose the Costa Ricans got their gear?

 

[BruceWard]

The tension on the cable can be calculated as Tension=(Weight of cable, trolley and passenger x Length of cable in feet) / (8 x Sag of cable in feet).

For example a 700' 3/8ths cable weighing 175 pounds with a 300 pound passenger and 25 pounds of trolley sagging 20 feet at the mid point would have 2187.5 pounds of tension on the 14,400 pound break strength cable.

But if the cable only had 3 feet of sag the cable would have 14,583.3 pounds of tension. With anything less than 10 feet of sag it is likely that cable would be damaged and eventually fail.