Double Whip Tackle

emr

emr

Cheesehead Treehouser
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Neenah, Wisconsin
I am trying to get my mind around the double whip tackle concept. I have seen it online as well at a couple of conferences. They always showed how to set it up and they talked about some benefits and limitations of the system. My first question is with regards to the gear needed. I assume that you need a GRCS or the like to do the lifting/tensioning. Next you need some extra long rope because of the extra legs in the system. Last you will need at least 2 blocks. I guess I was wondering about the diameter of rope needed. We currently only have 9/16" rigging ropes and I am not sure if that would be strong enough. I know it depends on how large the wood is that is being rigged, but do you need to step up to a larger size just because of the additional force to be put on the rope.

My next question is do you need to step up to larger slings as well. We currently have 5/8"slings to go with our 9/16" rope.

Next spring we will be getting a 5/8" rope and some larger slings, but for now 9/16" is all we have. I dont have any jobs that I want to set up a DWT, I have just been thinking about it.
 
Like you said it would dependent upon what your are rigging. That force can be deferred through extra blocks and better rope angles.

Did you read the article by Todd Kramer in the new TCI mag?
 
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Yeah, that was one reason I have been thinking about it. He came to the WAA winter conference acouple of times and talked about it as well. I never really paid too much attention to it because we never had a GRCS before. Now we do so I am playing catch up on some of this stuff.
 
The GRCS gives substantial MA as it is, no? If you're going to be needing so much lift/pull that a 4:1 block and tackle set, powered by the GRCS, is needed, you better be going big on all the rigging.
 
Burnham said:
The GRCS gives substantial MA as it is, no? If you're going to be needing so much lift/pull that a 4:1 block and tackle set, powered by the GRCS, is needed, you better be going big on all the rigging.
Click to expand...
Go big or go home! I had to set up a 6:1 powered by a Masdam rope puller not because I needed the power but because my groundy was a 73 year old man and needed the ease of pull.
 
Using a dwt or bigger means you can use smaller rigging, not bigger. I have a youtube video of us using the grcs and a twt to lift and lower 95' of broken pine in one piece. My youtube channel is "theRutherfordtree" if someone wants to embed the video. I'm pretty sure its title is "Cruise Pine."
 
With back yard rigging, before the GRCS came about, on hard pulls I used multiple Masdam rope pullers connected to the actual work line. Once 6 Masdams to do the pull with two of the Masdams pulling through blocks for double purchase. It equated to about 10,000 lbs of pull all together. Individual anchor points for each puller.

Old school rigging. It will get you by in a pinch where you can't get any other machines on site.

On the bad side,,, it's a long slow process.
 
lumberjack said:
Using a dwt or bigger means you can use smaller rigging, not bigger. I have a youtube video of us using the grcs and a twt to lift and lower 95' of broken pine in one piece. My youtube channel is "theRutherfordtree" if someone wants to embed the video. I'm pretty sure its title is "Cruise Pine."
Click to expand...

Not sure I'm following you, Carl. If you have the capability through ma to move bigger loads, the gear used to attach to the load, and to the anchor points, must be stronger, too...no?
 
a half inch line can only hold what a half inch line can hold
even with 23 blocks in a star configuration pulled by a team of mush dogs.
 
Bodean said:
a half inch line can only hold what a half inch line can hold
even with 23 blocks in a star configuration pulled by a team of mush dogs.
Click to expand...

This. The working load of the rigging line will mostly likely be the limiting factor, and possibly the anchor points on the tree.

Sent from my Desire HD using Tapatalk
 
For hypothetical's sake, 23 parts of 1/2" line can hold 23x the weight of one 1/2"line. Using dwt+ lowers the load on the lines and depending, the rigging points.
 
I'm not buying that one. The ma only increases the pull at the working end of the system, it doesn't spread that part of the load at all.
 
How or why would you put multiple blocks on the same sling? A dwt with 1/2"rope and suitable blocks and sling is as strong as a 3/4" single line.
 
We need a diagram to discuss this one, methinks. But anyway, that 1/2 inch line at some point has to attach to the load, doesn't it? The single leg carrying the load at that attachment bears the full load that the ma brings to bear, doesn't it?
 
That is what I was thinking. Is that called an open system?

If the system is closed, like in the picture below, I could understand how the line never takes on the full force of the load.

phy4.jpg
 
Perhaps the rope doesn't in that setup. But the hooks all do, as representing rigging attachments we need to beef up, don't they?
 
I thought this thread was about a double whip tackle and variants? That picture would be a quad whip tackle.
 
And you're right, the rope on either side of the moving block carries half the load that would be attached to the hook.
 
But I still maintain the point I made in my initial post...if the pull you can bring to bear on the moving block is multiplied already by the gearing in the GRCS, you'd be likely to have the capability to exceed rigging designed to match a 1/2 inch line. So go big :).
 
With regards to the grcs and lifting, high modulus ropes are where it's at. In that case 1/2" rope is plenty adequate. My biggest lifts with the grcs have been with 1/2" high mod ropes, such as Warp Speed or Validator.
 
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