Big Snatch

[Emsworth]

it was a good advert for their slogan though. I dont see wht the deal was with all the wraps round the seperate trees? Surely they would have all locked up over them selves and the timber would have been suspended? Theres no way that would have gone smoothly is there? Can someone explain?

[Ty Korrigan]

been a long time since I had a rush!

 

Then my advice is to spend less time on the computer and take some of those mushrooms you come across...hhhh!

 

Ty

[Jake Andrews]

Then my advice is to spend less time on the computer and take some of those mushrooms you come across...hhhh!

 

Ty

 

:lol:

 

Jake:thumbup1:

[High Scale]

Nobody does big trees in Blighty anymore, we are all busy flying keyboards:)

Edited February 16, 2013 by High Scale

[scotspine1]

Looks like they saw the 3-strand rope, the natural crotching and the wraps on trees, and jumped to the wrong conclusion.

 

Joe, I was using 3 strand at the start of my career and still use 3 strand to this day (along with more modern rigging gear), dont have an issue with 3 strand, but I did doubt your judgement with the way you used the rope and rigged the timber. When I saw the shackle and how you'd cradle rigged it, in effect with the shackle acting as a massive subtractor of rope strength as the force is dissipating into the system. The more force was put on the shackle the worst the outcome was going to be because you only had a single length of rope through the shackle (albeit forming 2 legs of a cradle rig). Doubling the rope at this point with a cradle rig like you did and adding an extra shackle to decrease the bend ratio would help a great deal. Just an idea, good luck next time, be sure and post the vid.

 

what if you doubled the rope throughout the whole system including the cradled rig, so there would be 2 sides of the rope going through the shackle side by side instead of the one you have, this would = 100tons of breaking strength @ the cradled rig.

 

Essentially it would be same setup as you have but the whole rigging system is a doubled rope from the rigged timber at the top through the shackle, down onto the half hitch round the side limb and the wraps round the base of the trees.

 

the cradled rig would have 100tons of breaking strength, the rest of the system would have 50tons but remember it's the cradled rig at 100tons that's taking the bit hit. Also what about 2 shackles doubled up side by side to decrease the bend ratio?

 

.

[mistahbenn]

Nobody does big trees in Blighty anymore, we are all busy flying keyboards:)

 

:001_tt2:Carl you da man

[High Scale]

Cheers Ben, just my photo not me climbing.

 

[codz]

it was a good advert for their slogan though. I dont see wht the deal was with all the wraps round the seperate trees? Surely they would have all locked up over them selves and the timber would have been suspended? Theres no way that would have gone smoothly is there? Can someone explain?

 

When done correctly the wraps will not lock up and can be released gradually.

 

Everyone apart from Joe, myself and the crew that attended the workshop has had the privledge of hindsight from which to draw thier conclusions. It is easy to watch the rope snap then say yeah I knew that was going to happen. As Joe has stated, prior to breaking the piece off the majority off those onsite were confident we had a reasonable chance of success. The scale of the rope compared to the log looked reasonable, taking into consideration we had at least 2 parts of rope supporting the load at all points. The rope was re-directed through a 40 tonne bow shacke attached to the base of an adjacent tree via a cow hitch using 25mm double braid polyester line. The cow hitch became fused together despite the reduction and friction before it in the system when it was loaded. This gives us an indication as to how much force was being dissapated through the system, although that is hard to pick up in the video.

It would have been nice to be able to let the log run as we would normaly do in a working situation. The forces involved meant we could not accuratley predict the number of wraps needed which is why we were reliant on the dynamic charateristics of the rope to do the work for us.

Thanks for all of the positive feedback that we are recieving both from here and outside.

[Emsworth]

I wasn't having a pop, I was just wondering if i was right or wrong as. We all learn a lot from hindsight, and I have never done any thing that size so I was criticising, just trying to learn something. My question was more to do with whether it was standard industry practice to run a rope through the woods around multiple trees, you only need one wrap to go wrong to ruin the whole system.

 

 

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[josharb87]

What would have been cool is to have a dynometer (?) or what ever its called to measure the peak loading. At the workshops I've been to, being able to know the peak load on the riggin system teaches us something, far more than a big snatch breaks a rope, makes you realise the forces involved and the importance of using correctly rated kit-knowing, not guessing the forces is an eye opener for those attending the workshop.

Tbh I'd be a bit disappointed going to a workshop, seeing a demo with an obvious outcome and not being able to learn anything-just how much did the rigging system exceed the mbs? That was a 5ton log, but what force did it peak at when it snatched? How far would you have to let a log like that run/be slowed down before it was safe to stop it before it hit the deck?