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Using steel figure-8's in-line on a rigging line to slow/control its speed?

Discussion in 'Climbing and Rigging Equipment' started by eye.heart.trees, Jul 3, 2019.

  1. eye.heart.trees

    eye.heart.trees New Member

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    I haven't seen this but can't get it out of my head, am picturing using figure-8's along a rigging-line to create friction before the highest anchor-point, literally just string the rope through the 8's (1, 2 or more of them, each lashed to the trunk with a length of rope) in a manner where they're going 'in through the back / out through the front' meaning the weight/force as it hits the trunking would be on the dead-center back-side of the figure-8 (can upload a picture if useful), you could put 2 or 3 figure-8's in-line when setting-up your rigging line so that, when you make the cut, the piece's ability to descend your line is forced through a figure 8 (or 3 of them at spots on the trunk, you could even be directing the line a bit this way, and can't imagine you'd need more than 8-10mm rope for lashing the 8's to the trunking so they stay put at the heights you'd set)

    Do people do this? If not, why? The biggest worry I have is that adding so much friction to the rope could be bad for the rope, but at the same time I could just spread that load by using extra figure-8's in the system, am picturing using 3 or even 5 figure-8's on the standing leg of the rig-line so that when you cut the top or chunk something large the piece's descent is inherently pulled-through the figure-8's, you'd set a # of figure-8's based on how much friction you wanted to induce of course!

    Thanks for any advice on this, am guessing it's obvious I've never done much rigging before, am asking this in the spirit of purchasing because I was looking at the portawrap for base and a block for top anchor but then started thinking "why not just use [2] Figure-8's instead of a block?" as it'd slow descent which seems appealing (at first / when new) and then realized I couldn't think of any reason that 8's wouldn't suffice for the entirety of friction-control here!
     
  2. Haironyourchest

    Haironyourchest ArboristSite Operative

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    So you want to create friction up high, rather than down low with a portawrap? Will you be lowering the pieces yourself, from your position in the tree, rather than rely on a groundsman? If so, there is a device for this, I think it's called the Safeblock, it's a block of aluminium with three highly bevelled holes in it.
     
  3. Yarz

    Yarz ArboristSite Lurker

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    This statement as well as this one

    Make me think that you are talking about stringing them up the trunk, like a fishing pole. Is that what you had in mind? If so, that's possible, but may not add the friction you are looking for. Plus, with the Portawrap at the base, you shouldn't have to add additional friction, unless you want the friction in the canopy.

    If you are in fact thinking about adding one in the canopy as a rigging point to change the forces on the tree, then yes, it should work, but as Haironyourchest stated the SafeBloc is probably a better option. I'm not 100% sure, but I think I remember reading that Figure 8's can impart a twist in the line, which would be undesirable for rigging.
     
  4. Del_

    Del_ Get outside.

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    It sounds like a bad idea.

    So how does the ground person pull the rope back up to the climber after a piece is lowered?

    Friction is a two way street.
     

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