Double Block Rigging

X I didnt notice a problem when I was on the ground and my wonder gloves didn't take to bad of a beating. But we were fairly limited in what we could do with the trees we had. They were not large by any means.
When I was in the tree I didn't notice the piece staying close to me either. There is normally enough slack (rope in the system to get it to fall clear of the climber.
The other thing I noticed was when there was the short drop and sudden stop (as seen with a short spar) there seamed to be less movement in the stem. And the forces were low on the primary block and very low on the porti.
Again not the best method for use at the top of a 100' tulip poplar but may work out great at 50'. I haven't had the chance to play with one yet but I'm sure the time will come.
 
Has anyone tried this style on a climbing system?

Simple and retrievable with a RR fs.
Push climbing line through small ring then safety snap then back up to terminate at the large ring. Makes a floating bridge and ma to pull. I don't know if that is clever or dumb guess I have to try to see
 
I just spent a week in Kansas City working with Drew Nelson and Kristian Schultz. Those guys span rig all the time. Basically the same thing as double block rigging. You run the rigging line through a block on one lead and then dead end tie the rigging line to another lead. Then add a block to the rigging line between the span with a sling to tie off pics. We were removing entire leads with minimal shock to the system. You can drop out tops no problem, swing large pieces away from you and have your ground guy stand up stems easily with all the mechanical advantage. Then once the piece is on the ground you can limb it and lift the log with the 3:1 to load on an arbor trolley. I was super impressed with how smooth the system works. It allows you to distribute the force throughout the tree. To me it makes certain situations safer and more controlled. This system definately takes more previsualization to set up and twice the rope. If I get a chance I will try and put a video together.
 
LandonPainter said:
I just spent a week in Kansas City working with Drew Nelson and Kristian Schultz. Those guys span rig all the time. Basically the same thing as double block rigging. You run the rigging line through a block on one lead and then dead end tie the rigging line to another lead. Then add a block to the rigging line between the span with a sling to tie off pics. We were removing entire leads with minimal shock to the system. You can drop out tops no problem, swing large pieces away from you and have your ground guy stand up stems easily with all the mechanical advantage. Then once the piece is on the ground you can limb it and lift the log with the 3:1 to load on an arbor trolley. I was super impressed with how smooth the system works. It allows you to distribute the force throughout the tree. To me it makes certain situations safer and more controlled. This system definately takes more previsualization to set up and twice the rope. If I get a chance I will try and put a video together.
Click to expand...
Hell yeah , Can be a time saver too if the final piece is the one you have anchored end to . Like you say with some previsuallization ((((((( yeah I make up my own words too say that five times fast)and a long Hank of line it can make a removal Bing bang boom done. Xrings on a dead eye make for xcellent moving block in the system to for not worrying about how they fairlead into it. Some pulleys have not such rope friendly sides which can be a limiting factor if care is not taken . Cool shit.
 
Queastion for those that have used this this in the field with live loads. Do you find this to have any significant value or advantage over using two separate lines with proper lowering technique or just going smaller with the load? Obvioulsy it reduces forces in the line to a point by having three parts to the line ( no different than a 3:1 ma), but other than that is this true my worth a company or climber purchasing a line that is more than three times the normal length they would typically buy.... Just to have to let it hang on a Rack for the majority of its life? Or if you can see your self using this technique a large amount is it a better plan to purchase a Stien lowering device that can handle to lines at once and have two lines. The safety factor is better in this regard and your not placing a lowering line in a better poi,t of being stuck by a load falling.
This is all just first thoughts when reading this post and picturing this in action in my head using past similar rigging setups as key points to go off of. For sure is a tool in the box in any rate.
 
I and a friend use it and span rigging (a related technique and my favorite) regularly. The advantages of dbr over two rope systems are less hardware, less work for installation, and less manpower (for rope management). Also, dbr can be employed when there is no available MA device or system for tensioning and lifting. It enables one ground man to double his natural tensioning power, which is quite useful for climbers when a company doesn't want to buy a GRCS or similar device. Also, traditional rigging systems can double the load of a piece at the primary rigging point, whereas dbr reduces that load, allowing you to use parts of the canopy normally considered off-limits, so you have more options for rigging paths.

I do recommend purchasing a small, durable, rope friendly block that can take a few hits, since it will be moving with your load.

As far as ropes go, we haven't used more than 200' in the system, though, admittedly there have been a few picks that more rope would have made easier.

I'd like to hear what lengths other dbr users keep handy.
 
The times we have played with it have been very limited. But I have found extra length in rope was not necessary for us. We rigged the tops out with a single block (no space to land a huge top). The went to the dbr on the trunk wood as it needed to stop rather quickly to prevent damage to plant material (in one case) and a stone wall in another.
If I get my work done today I will try to put together a couple of my cell phone videos of what we were doing tomorrow. Definitely not an every day tool, but still in the box if needed.
 
I have retread the entire thread. I would love to see pics videos or diagrams for it in a pruning and removal scenario. I have some thoughts but don't wanna discuss the, until I'm sure I understand all this.
 
Steve,

Yes, about 12" below the main block is best for top down rigging.



Et al,

In the testing we did, lowering as during normal production (i.e. letting the piece run as best the situation allowed) we drasticaly and uniformly reduced force at the main or stationary block and hence the stem.

Of course some pieces had more room to run than others. We used varied cuts and changed other aspects of the rigging as well. All in all, the loads we measured in a "production" setting were consistent with what Gareth found doing more controlled testing with a single piece over and over as stated in the TCI Magazine article.

To give you an idea of our findings:
(These are peak force numbers)
In one case, the piece rigged with the double block system weighed 300lb. Peak Force at the main block was 194lb. with 456b at the POW

To compare, another piece rigged single weighed 178lb. Peak Force at the main block was 410 with 464lb. at the POW

Tony
 
Not to get off subject but what srt device were you using?
I'm looking forward to this at the expo. I've used it a few times and can definately see its usefulness. Thanks for sharing.
 
I do not recall exactly. I simply tied in with an adjustable friction saver, but since I was mostly behind the camera, my system is not really shown.

Seems to me Flyingsquirrill was on a Zigzag and real deal a pulley saver.

Tony
 
Tried this technique for the first time a couple of weeks ago and failed to predict the correct amount of friction on the POW. piece didn't run at all but also didn't take me for a ride...(it was also undersized being my first time)
 
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