Science of rigging

[Will Cobb]

Right I know this is a bit of an in depth thought but today I was thinking and I was wondering if anyone as ever worked out the weight transfer and forces of rigging the top out of a tree. The momentum of the fall would increase the moving weight but has anyone ever worked this out, I know a lot of this would have to be done for testing rigging equipment. sorry if all this sounds a bit stupid but just a thought I had today.

[Dan Curtis]

It's well documented in various publications. For some light reading try;

 

http://www.hse.gov.uk/research/rrhtm/rr668.htm

 

And there are a lot of good downloads available at http://www.vtio.org.au which cover forces and loading

[Will Cobb]

Cheers Dan will check them out

[Dan Curtis]

There's a few bits scattered around other places as well but I can't recall the locations of the other Internet based ones. They should give you more than the gist of things though.

[DrewP]

Try this- [ame=http://www.youtube.com/watch?v=Wg_hqCrtBrM]AA Rigging Awareness Workshop - YouTube[/ame]

 

If it is what you're after book at at- Rigging Awareness Workshop Tickets, Exbury - Eventbrite

[Marc]

Right I know this is a bit of an in depth thought but today I was thinking and I was wondering if anyone as ever worked out the weight transfer and forces of rigging the top out of a tree. The momentum of the fall would increase the moving weight but has anyone ever worked this out, I know a lot of this would have to be done for testing rigging equipment. sorry if all this sounds a bit stupid but just a thought I had today.

 

I have thought about it, the problem is the variables are immense, for example worse case scenario a 150kg piece can achieve a peak force of 1500kg (x10) when snatching. In perspective that's a bit of timber about twice the weight of an average climber turning into 2 trailed 6" chippers being dumped into the rigging system, given that the safe working load of your average rigging block by ISC is only 15kn or 1500kg and your average 16mm rigging rope around 800kg you can be pushing the limits with only small timber.

 

Reality is different, letting timber run, dynamic absorption from the line the length of rope in the system etc.

[arbogrunt]

agreed. you can guestimate the weight and dynamics of pieces of wood...but we all know when were 'pushing it'. Common sense, big ropes and smaller pieces work every time...well, most of the time....