Calculating load on a speedline.

[Mark Bolam]

11 hours ago, Ian Clarke said:

if you can get a copy of The art and science of practical rigging.  its published by the isa that will have some good information in there one of the bits it does say is that pieces of timber should not be dropped on to a tensioned line. they should be first arrested in a normal rigging point below system then. the speed line tensioned and then they travel down the line.

Great book Ian, but Pete Donzelli died when a tree shat itself.

Always worth remembering that they are the unknown factor.

[tree-fancier123]

It did put me off the book when i read that in the back, nothing wrong with the content, very informative, but knowing that the author didnt know enough to keep himself alive, sod hazard trees, cordon off the area and let them fall down

[Ian Clarke]

Accidents happen. There have been many near misses. And unfortunately there have been some deaths. 

 

Saying that he didn't know enough is a bold statement. I also will say I know none of the specifics of his accident. 

 

There are trees that look sound but rotten as .......insert words here.........

 

Also I always feel there is something to learn from every situation and scenario. sometimes it's what not to do. 

[carlos]

i find these threads regarding rigging interesting but i must admit in my years of doing tree work i have never once known the weight of any bit of wood i have rigged! any one else the same??

carl

[Ian Clarke]

I do agree with you Carlos a lot of It is done by experience. Also communication with Groundie controlling the weight and the feel of the trees reaction. I will say that in normal rigging you utilise the trees compressive strength. I'm zip/speedlining you are pushing the boundaries as you can quickly push the limits of anchor points. I will say I've not had the chance to work out weight of Logs on an actual job but that's more time constraint issues also we are not setup to take massive logs away so we have to cut things small for handling purposes so nothing is big enough to push the boundaries. 

 

A job I was on once *as a Groundie was a crane job and the driver could tell the climber how heavy things were and how close to his safety limit he was. But they were lime trees that were going straight through a tw350 in 1 piece about 20ft long. Otherwise it may of have to be smaller to get it out. 

[carlos]

yet another impressive vid by august hunikie , id say you would want to know what you were doing before putting that much load on your gear!! mega lumps.

[sime42]

At some point in the August Henkel video he mentions using a guy line on the tree being used for the speedline line. In cases where there is concern over the weight of logs been dropped relative to the strength of the tree. I think this is a very important point as if a suitably strong enough guy line is used then you're back to utilising the trees compressive strength rather it's much less reliable bending strength.

[Dilz]

if doing anything serious - then really the piece needs to be snatched on a normal rigging set up and then the speed line tensioned. Everything i have read says that you shouldnt shock load a tentioned speedline.  - The reality is some what different....   

 

One trick I use on speed lines is to have the line on a base tie, then you can run it through a block or a crotch,  dont know how this affects the loading, but i like it as a set up.