Rigging Scenario. Has anyone done this before?

[Kottonwood]

Thanks again Imagineero.

I usually rig on a 5/8 line, though I just got 200 ft of 1/2 in stablebraid that I haven't used yet.

I definitely agree that the prussic is the way to go as far a a friction system. I can't think of any mechanical devices that I would trust to hold that sort of load.

What type of line do you use for a prussic? Definitely need something strong for the forces it has to handle.

 

[squad143]

I perfer prussics over a rope grab in most cases. If overloaded a prussic will slip, where as a rope grab will bite into the rope and desheath it. (or worse).

When anchoring the base of my speedline, I usually terminate it on a portawrap. I'll use a seperate 3:1 haul system to tension the line and then take up the speedline slack in the porty and tie it off. Then I'll take the tension out of the haul system.

Major advantage of using the porty is that when you need to release tension on the speedline, it can be done quickly and safely. (under control).

Sherrill sells a fiddle block kit for adding mechanical advantage: Fiddle Block Kit : SherrillTree Tree Care Equipment

However, at $300, I'll keep using the many pulleys that I have.

I find that I never have to use more than a 3:1 MA when tensioning my speedlines.

For tensioning lines, I perfer the VT knot (french prussic) using beeline with eyes. This knot grabs both sides of the rope and is easy to undo, even when heavily loaded.

 

[mpatch]

And After:

is the job complete in that pic?

 

[squad143]

is the job complete in that pic?

Except for stacking the wood that is beside the garage and the small hanger, Yes.

 

[beastmaster]

Yeah, this is exactly what I was thinking about, glad to hear that someone else has done it before.

So do you use a port a wrap on the bottom for the groundman or are you using some other friction system?

PS I believe it's "bowline"

It depends on the size of the wood. When we have a pulley up high and removing heavy pieces we'll use a hobbs devise. Sometimes I'll just have the guys hold the rope if I'm just speedlining some small stuff, or have them tie a knotless truckers hitch at the base of a tree.(some times I tie off to the truck)
A porta wrap works good , also a come- a- long with a prussic will work in a pinch .
Sometimes you can set it up, and not even be tied into the tree your working on but to an other leader or near by tree, so when the piece is cut, it's slingshoted off and out and hangs off in space between the two attachment points tell its lowered down staying in the middle of the two.
Having the pulley higher then the tie in point has its place, but its not as fast as speedlining. It works pretty good if your craning off an other tree and start running out of room to swing, you just tie it off and your set to go.
Thanks, of course it "Bowline", Its been a hard week. Beastmaster

 

[imagineero]

Thanks again Imagineero.
What type of line do you use for a prussic? Definitely need something strong for the forces it has to handle.

There's a read worthy report here;

www.paci.com.au/downloads_public/.../03_Tests_Equipment_BWRS.pdf

where a local australian rescue crew got ahold of a load cell and did a bunch of tests on what weight you can hold with different devices, fail points for different devices and different types of prusiks. It's not exactly riveting, but worth a flick through. I've traditionally used 5mm or 6mm exotics on my 12mm because I always think anything bigger wont bite, but it depends on the prussik not you choose i guess. In their tests when the 8mm held it did (obviously) hold more. There are other users on AS who have a lot more experience and knowledge about prusik materials than I do. I remember from reading that some prusik materials are very grabby, so maybe that opens up the whole 8mm route a bit more, and if you are using 9/16 line then 8mm is definitely more of a possibility.

JUst remember that you'll get theoreticall double the breaking strain of the cordage used if you use a standard prusik knot. In reality, it's a bit less due to the loss of strength at the knot, but if you have a SWL of say, 1500lbs then with a looped prussik you could expect about 2500lbs. THe results of the tests show that the prussik will fail at lower than the SWL of the cordage though.

Shaun

 

[imagineero]

the above link somehow got crossed up with another one I had and doesn't work anyway ;-)

The correct link to the research pdf should have been;

http://www.google.com.au/url?sa=t&s...sg=AFQjCNH6Cu5f_Vm_RknknFWm_8PnLaQO7w&cad=rja

The interesting thing was that the ascenders mostly passed their rated loads, despite being 20 years old in some cases, while the karabiners failed at much less, in one case at little more than half the rated load (!).

Another good research paper from the same bunch shows slip and fail points for many types of hitches and cordage combinations including the distal and VT. Was interesting reading for those who climb on hitches. I climb in devices personally, so it was pretty much just academic for me;

http://www.google.com.au/url?sa=t&s...sg=AFQjCNFhL-zn1dgzVz915sMmc-w4dHHFWQ&cad=rja

Shaun

 

[mpatch]

Except for stacking the wood that is beside the garage and the small hanger, Yes.

that's what I was wondering, if you saw the hanger.

 

[squad143]

that's what I was wondering, if you saw the hanger.

Good eyes.

I usually try and take care of hangers on the way down, but I believe with this one it was too far from the spar. A throw ball on some thin line is all it takes to pull them down...... usually:msp_laugh:

Good job man the birch seem brittle to me

Thanks Rope. The biggest thing I dislike about Birch is they seem to die from the top down. A few times I've found them "soft" a lot further from the tips than I thought they were when I quoted the jobs. This can turn an easy job into something more than I had planned. I've since learned to factor this in when quoting them.

 

[squad143]

Here are a couple of videos I posted a while back.

Both of these trees were on the same property (same day).

The trees angled over the rocks/water.

Most of the branches were speedlined and the blocks chunked out, either by directional pull line or cut and chuck.

[video=youtube;DXhIB8hRcXE]http://www.youtube.com/watch?v=DXhIB8hRcXE[/video]

[video=youtube;zC6ptlpH0r8]http://www.youtube.com/watch?v=zC6ptlpH0r8[/video]

 

[flushcut]

Nice, so who got their feet wet going after those chunks in the water?