Rec Climb Help

[tnttree]

I am helping set up the 06 Tree Fund Climb in Mpls. I have this crazy Idea to incorporate a 1200 foot zip line ride off a bluff overlooking the mighty Mississippi and Minnesota river down to some big ole cottonweeds.
My question is what are the forces generated at the anchors by tensioning off such along line? I prefer the yellow line route because of less obstruction pre pruning.

 

[tnttree]

Not too worried about anchoring off in this big boy, but on the Fort side there is a 3' concrete pillar I want access too. if I can't get that permission than I may have to settle for a 20" bur oak.
I've set up several 400' ers b4 and wasn't too worried about my anchor points. This one's lots longer, I think I'm pretty safe with a 5/8 stable braid? what do you think you would want to see b4 you'd ride her?

 

[tnttree]

View from the Bluff

 

[Zac]

the line would have to be really tight for a 1200 foot run, how do you plan on pulling it?

I want a ride!

Zac

 

[Colin]

Me too!!!

 

[Raven]

Man that's my old stompin' grounds, count me in!
It's also sacred ground - Native American internment camp during the 18??s, can't remember the dates.

I try to use a double line like Jerry B. and the gang on the Bogachiel Spruce Climb but I think one 5/8 Stable Braid would look good to me, how you gonna tension it, some kind of power winch? I don't think the fiddle block would cut it. As far as extra force, I don't think you're really amplifying the force just because of longer rope, think about it - imagine picking a 1000# log straight up with say a ten foot rope, if you lift with 1000# of force you will exert 1000# on the log after the stretch is out of the rope, now use a 400' rope, how much force must you exert to pick up the log? 1000# right? now use a 1200' rope, same thing right?
In my example I'm lifting straight up, now for a zipline you are pulling laterally so you'll have the extra weight of the rope to consider, how heavy is 1200' of Stable Braid? not too much for that big ole Cottonweed.
Now TreeSpyder or someone else may have some math to prove me wrong (love to see it).
If anything for peace of mind you could install a big fat guy rope on the river side of the tree, now that would look good.
I'd sure love to have a ride on that thing.

 

[tod_k]

There may be additional force with the great distance. If you use stable braid you would need alot of force just to get the strectch out.

 

[scott_baker]

I have some friends that have been setting up Tyrolean traverses for fun for years up to 500'they have a piece of 'crab pot line" that has almost no stretch. I don't know what it was but it looked kinda like tenex. I would try to get the lowest stretch rope you can for this length. Does anyone know if they can they even make a single 1200'piece of stable braid? Passing a knot might add to the excersise!

I would think that you need not try to get the rope too tight just end the slide in the natural belly of the system and have the slider equipped with ascenders to climb up to the exit tree.

I have been helping set up some 350' cable zips and when the rope that will pull the cable across is first set we have often had to go across to clear it. We found out quick that you had to be ready to haul yourself up the rope where it was over stuff and up the oppsite side of the low spot.

How are you doing with permission/permits? Who owns the land? I am dealing with the USFS at the moment about a permit for tree climbing. It seems like they are not aware of how much this rec climbing thing is happening. The application that they are using is for something completely unrelated. I will post something when I know more.

 

[tnttree]

Hey Thanks you guys, Need to get Insurance issues worked out before approching the Honchos for the Fort and the State Park. The Park seems like a shoe in the fort Anchor is the tough one. A GRCS will tension the line, we will have control lines on the Porthoff trolley. Considered Static, but I am not to familiar with it. I'm courting Rope sponsorship from Sampson, apparently you can get 2400' hanks? thats not confirmed yet either. I like the Idea of a double line . . . Just Because, But I believe Raven, a single 5/8 should hold. I will solicit the spyder advice. posted a pic of the landing Pad. Gotta hit the road for a week here

 

[Tom Dunlap]

If your design requires a straight line, not a V, you will have to tighten the line. In order to do this, like TK says, you are going to have EXTREME loads built into the system. Just like in treework, the weak parts aren't the rigging gear, it's the trees and anchors.

There is plenty of information and safety protocols that have been developed by search and rescue technicians that can be used to setup a zipline. The math isn't that complicated but it does need to be done in order to have a safe system.

The zipline at the Bogiechiel Spruce was setup by Knut Foppe.

I googled...design a "tyrolean traverse"...and found LOTS of good information.

Take a look at how the pros set up highlines:

http://www.firerescue1.com/firerescue-magazine/23-8/10291/

Be sure to read the gray box at the bottom of the page!

Life on a Line is another good place to learn more about ropes and rigging:

www.draftlight.net/lifeonaline/ download/download.php?section=2

 

[tnttree]

Good stuff Tom, Thanks, those boys have some nice toys.
A sloping line puts less stress on the track speed line, so I have that going for us, and it seemed like most of there lines were single tracks. A nice belly in the rope will make for a safer and challenging ride.

The Tandem Track tensioning system is cool way to tension two lines, but I think they should have tied off the slack in the track lines after tensioning -- two portys would work great for that. /forum/images/graemlins/cool.gif

Quote
[The three main components of any highline system include very reliable anchors at each end of the highline, the highline rope itself (referred to as the track line) and tag lines, which are operated from each side to move the carriage pulley or pulleys across the rescue area. Important: Tag lines can also function as back-up belay lines should the track line fail.]

Did I understand that right? so if the track line failed, the two belay lines would back it up? So both tags would have to be kept taught to catch the load /forum/images/graemlins/bigeyes.gif SCARY but do-able. two track lines seem way safer! god forbid the main line failed.

/forum/images/graemlins/cool.gif The coolest Rig was the Engish reeve with optional belay, I have tryed to figure that one out B4 for another situation, wasn't Frans looking to try to do that on an earlier thread?

Comes down to anchors for sure, I was glad they added pad the rope on that girder anchor picture that was questionable on first glance. The Cottonweeds will be backed up thats easy. And the Fort well ... Ten tons of concrete+ well I think we have adequate anchors.

This is going to be a fun project!

 

[tnttree]

Whoops, Tophopper GPS the site the other day . . . ahh zip is really only 400' ( can you trust that thing? /forum/images/graemlins/shakinghead.gif) , I must of zigzaged quite a bit around the underbrush to come up with 1200'. sure looks like that far from up on the bluff. oh well 400' will be fun. still work'in on permissions. /forum/images/graemlins/blunt.gif

 

[tophopper]

400'

1200'

ah, whats the difference?


Yeah know dave theres one sure way to find out...
maybe we should get over there again with a big shot and throwline and fire off a few shots from the tower. It would also give us a good idea how smoothly (or unsmoothly) set up will be.

having thought even more about the rope to use, I now feel even stronger that we should consider Amsteel or something similar with little to no stretch.
Bull ropes are designed to stretch and there will definatly be alot of it with a span of even 4-500 feet.


Anyone have 1000-1200' of Amsteel they'd like to donate? /forum/images/graemlins/grin.gif

 

[Norm_Hall]

Try a static line. It will be alot less costly than Amsteel.

 

[Zac]

I've used KM III for recreational zip lines before, no complaints. A lot easier to tighten it without the stretch factor. Also a lot cheaper than amsteel....

 

[tnttree]

I think Sampson should donate this amsteel to this tree fund event, I be calling these boys, Ox gave me the contact.