How much weight can a rigging point hold?

[davidwyby]

Perhaps it’s in FGTW, but I’ll ask. I have not rigged much, always cut ‘n chuck. We want to rig the limbs hanging over the grass and fence over to the tree on the left, then pull both down left. We want to keep the pieces large to be drug away in fewer trips and dealt with elsewhere. Dead dry brittle oak. Is there a rule of thumb for determining how much limb a limb can take? Thanks

 

[Mick!]

How long is a piece of string?
Just got to use common sense.
Don’t go big just to save a few minutes clear up.

 

[friedrich]

start small until you have more experience with it. on some trees even a 75 kg piece can feel huge and on others 1000kg is not a problem..

 

[flushcut]

A rigging point will hold as much weight as it will take to break it.

Lighter is better.

 

[lxskllr]

Seems to be experience. Every tree is unique with unique geometry. If you have time, and there's no consequences, you could load some of the non target limbs to failure to get an idea of what you're dealing with.

 

[flushcut]

Geometry aside, is the tree healthy? Hollows? Rot? Insect/animal damage? Just to name a few…..

Being a tree guy it’s pretty rare that I get a call to deal with a perfectly healthy tree. Most of the time the tree in question is compromised in some fashion or another.
Hang more blocks in the tree for redirects to counter balance forces, cut smaller.

 

[Altissimus]

It's exactly like judging a tie in point to climb ... only bigger and more complex

 

[SeanKroll]

Vector forces factor in strongly, along with peak loading...snubbing off versus letting it run.
Elasticity of rope is an important component, along with the amount of rope in the system.

 

[gf beranek]

until it breaks

 

[Bodean]

Move the fence…..

 

[flushcut]

Pull some posts, floppy floppy, munny munny, easy peazy japaneasy lemon squeezy.

 

[CurSedVoyce]

Rigging off dead = small pieces and better if not on gaffs tied to dead as you cut.
Going big on dead means you eventually find not all dead is alike and breaks readily if stressed too far. This point costs you time and money when it does.
Experience is your friend and until you dead with enough dead oaks, keep it cautious. Better more clean up than someone or something hurt.
Even a crane can screw it up with the inexperienced.
You can also half hitch your way down the limb as a back up plan if it gets too punky. Or loop runners like a zipper. Prefer that.
Slow, steady, small, try not to shock load.

 

[flushcut]

Smooth on rope too!

 

[CurSedVoyce]

Look at how much the wood is already holding up. Cut 1/4 that or a 1/3.
Did it just go through a storm. Is the wood checking? Look at all your variables. Moisture content changes thing. Rain?

 

[SeanKroll]

You're dealing with deadwood above you and shock-loading from rigging. Look over the whole tree to identify hazards.

Throwlines are your friend. Pull on loose hangers and break out weakly attached wood and watch/ listen/ feel the tree react from shaking before rigging on it.

Pretensioning, positive and negative rigging reduces shockloading, such as with a Rigging Wrench for light weights and GRCS/ HOBBS/ Stein bollard with winch/ etc lowering devices. Stretchy ropes reduce shockload (polydyne, for one example)



When rigging, make a plan between the cutter and roper of what is supposed to happen when everything goes to plan.

Make a plan between the cutter and roper of what to do if something goes wrong, such as the piece breaks off earlier than expected when rigging to swing sideways and downward. If the plan is to keep lowering the piece steadily to the ground, and it prematurely breaks in a different location where continuing to lower will put the rigged piece directly into a fork, the roper have to know to steadily decelerate the rigged piece to a stop much earlier.
What should the roper do if the rope gets fouled, snagged or redirected by a limb? What if the cutter get caught in the "bite" (sp?)?

In the spring of this year, a heavily-loaded rigging rope snagged my carabiner saw hook (a paddle biner with the gate taped open, a la a Caritool and Shembiner combo, can be used with and without the gate, but pre-dating them) when the rope took an unexpected path past me, due to premature breakage from decayed heartwood, and was running through ithe saw hook, pulling on me a bit. It was the first day of warm, sunny weather and I was in short sleeves. I got some rope burn on my arm. Not much, but it was a lesson learned...clothing definitely can be protective.