DWT on spar

andrus kokerov

andrus kokerov

Participating member
Location
Estonia
Hey!

I watched a video on climbingarborist.com about the DWT rigging system. They used it on a stem and under the video there where meny coments about smashing the block into the stem. I would like to see what you guys think. Would you use it? The video is here:



Andrus
 
This is pretty much my go to method, along with a rig n wrench, it's great! No more Porta wrap, no more running around the base of the tree. Nice control.
 
Steve Connally said:
What do you mean no more porta wrap?
Click to expand...
Since the double whip has a nominal 2 to 1, the leg used by the groundie has half of the force, so he or she can hold twice as much without basal friction. It's pretty sweet for use with inexperienced groundies, skinny spars, and sketchy situations.

Double whip is also great for lifting, like with windthrown trees on structures with no crane access/availability. ane access/availability. Double your GRCS fun!

My favorite use, though, is what I call the auto-drift line, usually for getting stuff that's over a roof or similar: the main block goes in the center, close to equal in hight with the piece you're taking, not as high as with a regular rigging line. The working end of the rigging line is secured just inside, i.e. proximal to your cut, and you make your face or undercut, often oriented for lifting to take advantage of the 2 to 1. The moving block is then secured to the piece, and when it the piece comes off, the groundie only holds half the weight and it will gently settle at a point between the block and the tied off working end. The working end doesn't have to be tied off at the cut, either, it can be farther in or on another lead so the the piece moves on two axes, but that can make the moving block more difficult to get back. Using the double whip and a ghetto version of the Stein 3 to 1 pretension pulley, I have lifted some hefty pieces from over obstacles.

Sent from my XT1080 using Tapatalk
 
Makes sense to me but say if you are roping 500lb logs off a spar would you not use a porta wrap. Just the inertia of the drops alone would likely rip the rope out of your hands.
 
I'm going to modify my post. I don't really do this on a spar with big chunks. I'm just thinking of DWT in general. sorry for the confusion. I am a huge fan of DWT for everything else but not so much for the spar and big chunks. sorry was posting in haste.
 
I think the confusion was brought in on the original post with the DWT. I wanted to try and clarify with Andrus to see exactly what the question is.

DWT as mentioned is more for lifting in more of a static situation. Like mentioned, lifting wind thrown trees from structures and maybe rigging large leads as one from above.

The video posted and the other thread is double block rigging used in dynamic (negative) rigging of spars. Yes both techniques use 2 blocks but the application and forces on the blocks are very different.

Maybe I'm a complete idiot and I'm over thinking it but I think we are trying to talk about 2 very different techniques.
 
andrus kokerov said:
Hey!

I watched a video on climbingarborist.com about the DWT rigging system. They used it on a stem and under the video there where meny coments about smashing the block into the stem. I would like to see what you guys think. Would you use it? The video is here:



Andrus
Click to expand...
This is a great and diverse system all around. When doing spar work, like in the video, I discovered less movement of the spar. This ment for me I hurt less in the smaller stuff-less violent shaking. I also discovered if using it, one could pretension the rigging line more easily which would then help move the piece over that was being rigged. One can use a smaller rigging line since there are now 2 sections of rope being used. Of coarse, other advantages mentioned in the video. Notice the numbers generated by the rig as opposed to rigging with a single block. Less tension in the line transfers less force to the spar-an advantage. One can also control the lowering speed which is an advantage in tight areas. When I used this system, I was aware of the potential for the block to take abuse. I set my rig so the rigging sling attached to the piece to be removed allowed the floating rigging block to stay clear of the rigged piece. The block needed to be placed below the face cut. The block did stay clear.

This system has been my silver bullit. It can be attached nearly anywhere in the tree. Split rigging points gives this advantage. It is a combination knot and knotless rigging system consisting of a rope, 2 blocks or pulleys, not everything we do requires heavy rigging tools, carabiners, slings and potentially more pulleys. One can set a primary rigging point within a tree, and move the static end throughout the tree, taking it with them wherever they need to be. If the primary rigging point is not in a good spot for some of the removal, simply place a redirect at a good alternate rigging point. Like speedlining, a good supply of slings and pulleys can be helpful. I hate it when they get caught on stubs and branches when moving around. When setting a single rigging point for heavier rigging I used a near tensionless anchor for the static end of the rig. I used 4 wraps and terminated with a running bowline. To me this ment more rope used and less likelihood of knot failure. When rigging horizontal limbs I had more control of the rig because lowering could be done more slowly than with a conventional rig. Here is a publication which could influence the way you look at rigging.

http://www.webpal.org/SAFE/aaarecovery/5_simple_technology/basic_machines.pdf

For gin pole work, I have observed the static section of the rigging line being thinner when loaded. This means to me the strain in the rope will not be equal on both sides. Great system.

Joe
 
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