I rigged my first tyrolean tonight.

[Rick Brinkman]

Everything seemed to work ok, but I don't know if I had too much tension. My books all have conflicting information on how much to tighten the line.

I used my Bluewater II between 2 trees that are about 35' apart. I tensioned it by myself using a Z-rig. I didn't really crank on it though. I ended up with about 3-4 feet of sag when I hung in the middle.

Anyway, good practice for me.....

So....how bad did I screw up?

[Stridergdm]

Well, you're alive aren't you? So didn't screw up TOO badly.

Seriously, if it was simply you tensioning it with the Z-rig, doubtful you overloaded it.

General rule of thumb is you don't want to exceed about 120 degree angle.

Best case, would be 0 degree (this would look like a rope hanging down and up again, each leg supports 1/2 the load.)

The "flatter" it is (i.e. closer to 180 degree) the forces go up dramatically. Useful thing I found to do when I set up a highline was to take a few pictures and then later took a protractor to them and measured. After that exercise, realized I was flatter than I would have liked.

I want to do a few more highlines and take photos so I get better at it. Just have to find the time and equipment.

Hmm, just dawned on me too, that you may want to look at how high you rig on the trees. Even if the rope is not under too much tension, you can pull trees down this way unless properly backtied.

[NZcaver]

I used my Bluewater II between 2 trees that are about 35' apart. I tensioned it by myself using a Z-rig. I didn't really crank on it though. I ended up with about 3-4 feet of sag when I hung in the middle.

As Stridergdm said, you're still alive right?

Assuming your anchors are sound and you don't weigh a thousand pounds, that setup using 11mm rope with 3-4 feet of sag at 35 feet sounds OK to me. Sight unseen, of course.

Tensioning with a Z-rig is fine, but what did you use as a rope clamp to hold the tension? A regular cammed ascender, a Gibbs, a Rescuecender, a Prusik loop...? The latter two devices are probably better choices than the first two because they should slip a little if overloaded, rather than just stripping/cutting the rope.

Large forces can easily be created using tensioned horizontal tyroleans/highlines (see below), so backing up your anchors (ie trees) is not a bad idea. Often you'll also see highlines rigged with larger diameter rope (like 13mm), or with an equally tensioned pair of ropes - in which case, you'll need to use a wide pulley or Kootenay Carriage.

All good fun!

[NZcaver]

General rule of thumb is you don't want to exceed about 120 degree angle.

Best case, would be 0 degree (this would look like a rope hanging down and up again, each leg supports 1/2 the load.)

For rigging a regular drop using load-sharing anchors, yes. For horizontal tyroleans/highlines, a 120 degree angle is not usually practical. Can you picture trying to traverse a 100 foot wide span with a 30 foot droop in the middle? If you're crossing a river, you'd better start your rigging at least 30 feet up on each side otherwise you'll be taking a swim! I suggest about a 150 degree angle might be more practical... but this means your entire system needs to handle those higher forces - EACH side effectively sees about TWICE the actual load.

[Rick Brinkman]

NZ, thanks for that diagram. That's the best one I've seen so far.

A little more info on my setup:
Both trees were LARGE. I wasn't worried about using them as anchors.
I used a High Strength Tie Off (Tesionless) on one tree and a Wrap 3 Pull 2 on the other.
My rope grab was a 3-wrap Pussik.

It would have been nice to have a picture of it while loaded, but I was doing this by myself. Guesstimating....my angle was probably between 120 and 150.

[Stridergdm]

General rule of thumb is you don't want to exceed about 120 degree angle.

Best case, would be 0 degree (this would look like a rope hanging down and up again, each leg supports 1/2 the load.)

For rigging a regular drop using load-sharing anchors, yes. For horizontal tyroleans/highlines, a 120 degree angle is not usually practical. Can you picture trying to traverse a 100 foot wide span with a 30 foot droop in the middle? If you're crossing a river, you'd better start your rigging at least 30 feet up on each side otherwise you'll be taking a swim! I suggest about a 150 degree angle might be more practical... but this means your entire system needs to handle those higher forces - EACH side effectively sees about TWICE the actual load.

Good point. I was going off the top of my head there and confused the load factors of 150 with 120. (hey better to be overly conservative. ;-)

And of course each side effectively sees at least twice the actual load. Now put in a redirect of any sort on one end (say so you can raise/lower) the rope, etc. and that redirect might see as high as 4x the load, etc.

Fun fun how the numbers can multiple quickly.

Oh and good point about the gripping device. Though note, some informal testing some of the folks we both mutually know has shown that relying on things "slipping" may not actually hold up in actual use.

[chh]

Reviving this thread only because I want to know about the picture posted below by NZ caver.
Why exactly did you isolate the haul/belay lines on your trolly with the prussik loops? Just to make the 8's easier to untie after the haul or to make the ends of these lines accessable for some other reason? Shock absorption or other utility in the case of a failure of the tensioned line and subsequent shock loading of the belay/haul lines? Just curious. I've seen these rigs deployed before but never for human cargo, and they were pretty much the same, except for the prussiks. I know there has to be a good reason. What is it?

[cavedoc]

Someone will have better details but it's a strength issue. Using the prussik you get closer to the full strength of the rope and something that will take some of the force if the trackline goes. The prussik is preloaded but in a shock it will likely slip (read, absorb some energy) prior to any force hitting the knot, which of course is the weak point in the rope. IIRC there was some testing done (in BC?) in which they tried several ways to rig this then cut the track line when the carriage was in the middle. This set up survived most consistently. There's a video out there that demonstrates it.

[chh]

Ok, that's kind of what I was thinking. I was trying to think of some scenario where you would need to utilize the ends, but with the lower out line there it didn't seem really necessary. I'd like to see that video of the various configurations.

[snoboy]

You can order the video from [url=Rigging for Rescue]http://www.riggingforrescue.com/[/url]. Click on "Publications" and scroll down.

A Kootenay Highline system (not a tyrolean) uses the rule that an 11mm mainline will be pretensioned by no more than one person pulling on a 2:1. This is to maintain a 10:1 safety factor when dealing with a 2 person load.