U-RIG -- a new approach to MA for tree work

Tom,

Instead of using 10mm HTP, why not use 9mm HTP for this MA system ?

If the load is divided evenly among all the pulley strands in the MA system, an individual strand of MA does not need to be as strong as the rigging line. It should only need to match the MBS of the pulley. If these pulleys are rated at 36KN (18KN per leg), then 9mm HTP @ 22.5KN should have enough capacity. This would save you another 1LB of weight and take up less space in your kit.

If this MA is being reserved as an emergency kit, this could be made even lighter and more compact using Sterling 6mm Power Cord rated @ 21.3KN, however, you might need to use different cords for the friction hitches.

Is there something I am overlooking ?
 
Marden,

YOU understand a key point in configuring a handbilly or MA. There's no need to build them with such huge ropes except that they're easier to wrap your hands around.
 
Tom,

I was pretty sure you were going to say that :-) It is good to confirm my logic is sound...

The only other consideration I thought of is the smaller rope would warrant different friction hitches.

-Michael
 
Good thread, guys.

Marden, you and Tom are right: in the 5:1 lifting MA, the internal line doesn’t need to be strong. BUT when you thin it out below 10mm, two things go wrong … you can’t grab it and you can’t wrap a good prusik.

BUT BUT BUT, in the hauling rig setup, better rope means better WLL for hauling and tensioning, above and beyond what you can pour into a hand rig (Boreality, thanks for the tip on the handle) .

I happen to like the 10mm. Fits my style. Remember, OLDfart. But if I were to make a “professional version” of this rig, I’d go the other way, maybe all the way to 13mm HTP internally. Then the WLL for haul and lifting would be the same. This rig could take some very serious abuse. The cost would be 2 more pounds of cordage. So take a lemon and make lemonade.

I’m not partial to cams. You never see fiddle blocks in a recue system because the load can run. If I were forced, I’d do something like Fairfield’s rig with the SMC Tech HX. You don’t get the smooth control of a prusik but at least the working end is captive and the load can’t run.

Remember, this rig lets you put in long, high-performance two-layer prusiks, not just ratchet prusiks, not just bound loops. This is more like climbing performance in a setup for rigging. Better efficiency and smoother control than you expect from a rigging system.
 
Good news: the Sterling Aztek Tactical kit uses exactly this approach. I'm going to try it on the second RockO (the one farthest from the anchor). One trap should stabilize both binners.

sterlingaztektactical.jpg
 
Tom on your video you had the prusik cord instead of the porti. You say this works well if you rigging mid line on a standing line can you gie an example of what you mean or where that would be used I'm just missing something i think
 
hay Kevin,


This setup might be useful in a couple of situations: when the anchor is far away and you want the “controls” closer to you instead of at the anchor; or you already have a line under tension, you don’t want to release it but only add more tension ( I just want a shorter rope).
 
Tom D,

Years ago, you put me onto the Radium Load Release Hitch. I tried it yesterday with this new rig.

Put the Munter on the anchor binner and tie the Mule around the whole system above the second anchor pulley. Seems to work great.

The trick is after you tie the Mule, jam it down on the first anchor pulley. This automatically releases the Load Prusik and safeties the Mule.

The configuration seems way stronger because neither prusik is taking a bite on the line and all the bend radius are soft. It’s way above my pay grade to try to calculate something thing complicated but I’d GUESS it jumped from 17-20 kN to 36 kN for breaking strength.

But, of course, the pulleys are loaded and you can’t advance the lead prusik. So it can't replace a porty but it's killer good to lift then hold a load.
 
Remember, this rig lets you put in long, high-performance two-layer prusiks, not just ratchet prusiks, not just bound loops. This is more like climbing performance in a setup for rigging. Better efficiency and smoother control than you expect from a rigging system.

OF,
Do you know of test results as to at what force do these high-performance two-layer prusks begin to slip? My experience is it not slow and gradual, but rather dramatic with lots of melting. It would be nice to know some numbers for different configurations and different cordage and diameters.

Anyone?
 
What a great question, Mark. I was unhappy with the performance of the UltraTech load prusik. With great help from Luke and Nick, we're running tests on ice tail, focusing on exactly what you're asking about. Within a week, I'm releasing another vid plus these test results. Sit tight.
 
I've dialed-in the U-RIG design to my satisfaction and put up a “how to build” video:

<u>U-RIG build details</u>



The original video, previously posted, is here:

<u>U-RIG Pocket MA for tree work</u>



Another video, not previously posted, shows using the system as a Radium Load Release (thanks, Tom)

<u>U-RIG MA system – hard lockoff and load release </u>



<font color="red">
And here’s a very nice surprise from TreeStuff.com: enter the checkout code TGH01 and knock off 6% from your purchases. Thank you Luke and Nick!
</font>



The channel is getting toward 100,000 hits. I appreciate the interest and especially the comments and guidance. But I’m truly surprised at the level of interest in the U-RIG. In the first month up, it has TRIPLED the biggest peak I’ve ever seen on the channel. Whatsupwiththat?


OF
 
Tom,

This makes for a very nice MA system. I have everything but the small DMM biner and tried setting this up from your first video. It works quite well. This new video is a more concise explanation what you need and how to set it up quickly.

Beautiful job laying out the components and explaining the construction.

Kudos !!!
Michael
 
[ QUOTE ]
Tom,

This makes for a very nice MA system. I have everything but the small DMM biner and tried setting this up from your first video. It works quite well. This new video is a more concise explanation what you need and how to set it up quickly.

Beautiful job laying out the components and explaining the construction.

Kudos !!!
Michael

[/ QUOTE ]

Ditto! Very nicely done.

I have used a 5 to 1 system using double pulleys for years.
Is your system more efficient? Are the 'Rock' pulleys bushing or bearing?
 
Thanks, guys.

Marden, you move faster than I can knock out the videos!

Norm, yes, I believe it to be more efficient but I sure would like to have some test results on that.

The U-Rig maintains better rope separation than a set of fours. The crossed axels at the anchor really do matter. And it has more space available for better prusiks. Mostly you see sewn loops or ratchet prusiks used on a SOF.

BUT you could be using bigger pulleys and that could make a difference. Yes, the P22 is full bearing but it is 1.5" diameter. A 3-4" pulley would be more efficient internally within the rigging rope itself.

Life is full of trade offs, of course. I was clearly going for size and weight but still have 1/2" capacity and detachable components. If you want that, this arrangement is the best I've seen.
 
Wow. I may be the last one to the party, but I just tried 8mm Armorprus for the control prusik in the uRig MA system, replacing 8mmOP. Same great feel, maybe better, plus more strength and way more temp spec. Much better choice in this application, for sure.

Thanks, Nick!

armorprus.jpg
 
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