Zip Line

[Dark Wing]

Has anyone ever set up a zip line for river crossings. If so just curious on how heavy of cable to use and whether i should use a come a long or turnbuckle for tightening the cable.

[TreeGuy]

Originally Posted by Dark Wing

Has anyone ever set up a zip line for river crossings. If so just curious on how heavy of cable to use and whether i should use a come a long or turnbuckle for tightening the cable.

Hey Dark Wing. I have used the zips many times for my work. The tighter you can get the line the better. I'm going to make a few assumptions so correct me if I am wrong. If you are going tree to tree, make sure you select ones that are structurally sound (ambigious, I know, but it has to be said).

If you are intending to use the line to simply pass back and forth on, do your best to get it really tight, and as level as possible. On the other hand, if its purpose it to get something really heavy (ie a game animal harvested), work to ensure that the line is on such an angle that gravity will do most of the work for you.

With cable (best pick) you are going to have to find a way to get your come-along attached. For this I have to recommend a mechanical device called a microcender (a 'shunt' will also work). These are camming devices that lock down harder, the harder you pull.

Once you get the cable to the tauntness you require, go an extra 10% to allow for 'stretch', and then wrap the cable around the tree at LEAST twice. Lock in with your hardware and you should be good to go. I have a pulley that is specific to zips. It is almost shaped like a heart, and has two rollers. It works great and can be used for a multitude purposes (ie 6:1 'come-along' systems).

As one last point, you are going to need some line to retrive/control the zip pulley. If it is not going to be load bearing, I recomend the white marine line (6-7mm I think) from Canadian Tire. Cheap, but very tidy, strong and task oriented. Once set up all I can say is check, double check and then check again. Make it safe, and once proven, it can be a ton of fun too. I have yet to take the ride here in Calgary. Canada Olympic Park has just set a line up that goes down the 90 meter ski jump as a simulation. They reach speeds exceeding 140kmp! However, $50 for 30 seconds is a bit of a deterrent for sure. Good luck, and if you have any other questions let me know. I am sure the Reeves and Altaberg will have some really good advice to offer also.

Tree

[Dark Wing]

Thanks for the reply TreeGuy. I want to make a basic cable car design between a couple of big pines. The amount of weight I want to transfer will vary up to about 260 lb. What size and style of microcender would you suggest for cable. I'm guessing 3/8 cable will be heavy enough or can I go lighter. Thanks again Dave.

[Cappy]

I've set up a few high lines and have always used my climbing and rappeling ropes. No problem keeping a high safety ratio (Weight capacity of the system vs load) If you have a couple guys you can tighten the line with the use of a 3:1 (or higher) pulley, use a prusix to capture your progress and vector the line as you tighten it. (Vectoring is just moving it up and down). The vectoring just helps getting the slack out of the line. I'll look around for some pictures to give you a better idea and help you set it up. Try googling "Kootenay highline" and check out the anchors and safety systems in place. They are nice, if the main line fails the haul systems can safely pick up the slack and take the load.

[TreeGuy]

Originally Posted by Dark Wing

Thanks for the reply TreeGuy. I want to make a basic cable car design between a couple of big pines. The amount of weight I want to transfer will vary up to about 260 lb. What size and style of microcender would you suggest for cable. I'm guessing 3/8 cable will be heavy enough or can I go lighter. Thanks again Dave.

Dave, I wouldn't go lighter than 3/8, and in fact your system sounds like it is permanent in nature. I'd go with 5/8 in that case just to give you an added degree of safety, and the ability to haul larger loads just in case.

Cappy, thanks for mentioning the haul system and the Kooteny Highline. (I knew I'd forget to mention something). You make a good point with having the haul line for insurance in case of some sort of failure. Dave, if you ARE making it permanent and your set up anyway, why not run 2 cables. Can't hurt. Also, as far as I know, a microcender is a microcender, and I don't specifically know if there is one for cable only, however mine is for rope but works just about as well on cable if need be. Maybe check with MEC on that to be sure. As a final point (depending on the length of the line), I'd tighten it with a winch or a come along of some sort just to get it as taunt as possible. Good luck, and I want to see some pics!

Tree

[Dark Wing]

Thanks again guys. Its going to be winter project, gonna wait until the water freezes so no pics for a while. I'll have to check with forestry or SRD to see if it's legal as well. Its going to be about 15km into the Willmore so it'll be a lot of work to set up.

[bullwinkle]

You'll have to check with DFO as well the navigable waterways act.

[Dark Wing]

Parks Canada will have to ok it as well. Talked to forestry and they figured it was good idea. SRD was out doing some bear work and have no authority in that matter anyways.

[altaberg]

hi,

my recollection is that the "Microcender" is a trademark of some company (Petzl?). I have to find mine.

Just a couple of comments, especially if using ropes. Dual haul lines are a good idea. In high angle rescue you use dual Prusiks to tension the system.

Don't overtighten the line. With ropes you shouldn't be going past the 6:1 for tension.
If it's too tight you get some pretty serious forces when you hang anything on it.

Good luck

[TreeGuy]

Altaberg, you're right, microcender is a Petzel product. What do you think about using one on cable? I've personally done it many times without a problem, as a prusik is not an option on steel cable. I wonder though how it will hold under the necessary extreme requirements of putting up a proper zip? Do you know of one that is specific to cable? I don't. The reason I told DarkWing to use one is to give him the ability to get his line super tight, but then have the 'slack' in the end of the cable to anchor (double warp around the trunk and then hardware it in).

Tree

[Cappy]

Altaberg is right, my oversight. Any time you are loading a line you double up your prussix as an added safety factor. The prussix are nice because if you start to overload your system they will begin to slip, letting you know this before a catastrophic failure.