Recreational zip-line

[bonner1040]

SkyRocki,

There are Dyneema core sailing lines that are extremely low stretch and high strength:

http://www.westmarine.com/webapp/wcs/sto...-1#.UUENwI6bMyE

There are also Vectran Double Braids if you want to get really fancy.

I have never been satisfied with rope zip lines, but I have never used a dyneema doublebraid either.

 

[TimberJack]

I hope we can keep this thread going. I am working on a 221 ft. zip line at my friends house. We're mostly in the land clearing brush burning phase of the project. The anchor trees have been selected and dead wood prunded. I have ran mason string from the two trees so that I have a real good visual on what trees need to be removed for clearence. I feel that four to five feet on each side of the line is sufficent clearence, while still trying to leave as much of the risidual forest stand intact. What is your thoughts on this amount of clearence. Can't wait to post pictures as this project comes together, but it's being built five states away from me, so it's going to take quite a few visits.

 

[Richard Mumford-yoyoman]

Just curious but has anyone done the math on how much pull is put on a tensioned zip line? What would be the forces in play? The working load of a climbing or zip line should not exceed 10%, correct, or is it ok to put more on it as the potential of a fall load would not be there?

 

[lumberjackson]

[ QUOTE ]
Just curious but has anyone done the math on how much pull is put on a tensioned zip line? What would be the forces in play? The working load of a climbing or zip line should not exceed 10%, correct, or is it ok to put more on it as the potential of a fall load would not be there?

[/ QUOTE ]

I would recommend always observing the WLL.

I found these two websites to be helpful in calculating the forces generated:

Slackline Force Generator

WolframAlpha Sag of an Inclined Span

Example inputs:
First on WolframAlpha
Elevation difference: 0 ft
Span: 200 ft
Horizontal Tension: 200 lbf
Cable Weight per Foot: .2 lbf

=5 feet of sag

Then on the slackline force calculator:
Line length: 200 ft
Line sag: 5 ft
Person's Weight: 185 lbs

=1852 lbs of tension needed to hold a static load in the middle of the line.

Of course your load will be moving and your line will have stretch which are not accounted for in these equations, so keep that in mind. and obviously you will have to adjust the variables for your situation, but the forces get big quick!

 

[bonner1040]

I think 4-5' of clearance seems fair, I have done it with less for sure but it was dangerous. I wont say you couldnt hit something 4-5' away because I am sure you can, but I think you would have to 'try'.

leg sticks out 3-4' with 1-2' wobble??