Knots that absorb shock and their care

[TheTreeSpyder]

http://www.amga.com/resources/various/Sequential_Failure_Paper.pdf

Ol'knudeNoggin sent me this a few daze ago.

It speaks from the climbing world and how some knots grant some shock absorption characteristics to a system. But also; how after such a hit they should be retied; to recover these characteristics; and those that have paid the price for not dueing so!

[gf beranek]

Equations and formulas like that are way too complicated for me to appreciate. As an arborist I very seldom venture above my tie-in point anyway. 99.99 percent of the time my line is tight and supporting me. Shock loading? Never!

[stehansen]

That whole rock climbing thing looks sketchy to me.

[Blinky]

That whole rock climbing thing looks sketchy to me.

Yep, and therein lies the attraction.

[Bounce]

Yep, don't go above your tie-in and you can forget about all this. If you do, the consequences of a "lead climbing" fall would be much worse in a tree than on rock because the rope is static. I've done this once, and fell 6-8 ft before the rope caught me. It felt like my insides were squished into jelly. Even when I climb rock these days, I only top rope and don't risk this kind of fall.

[No_Bivy]

That whole rock climbing thing looks sketchy to me.

but fun........:D

[stehansen]

Yep, and therein lies the attraction.

Gotcha.:)

[NickfromWI]

I like rock climbing a lot. It's just a whole different ballgame. You have to really learn how to make the rock with you for your anchor, and your rope work with you for your energy absorption.

I would never resort to looking to my knots to absorb any of the energy. The ropes are bouncy enough as it is.

Spydie- linky no worky!

love
nick

[TheTreeSpyder]

Welllllllllll i look at it as a constant mantra and habit of maximazation that could glide you thru some rough point. i try to stay on a top roped, taut line, but; then there is also rigging we do with our lines.

A few points came to mind as i read this article. Like guys that claim they never or about never untie their hitches, eyes/terminations etc. Arguements about splice or knot etc. i think a lot of mountain lines are more elastic, but then the anchors less.

And the whole rope science extended. After a dynamic hit; some of the elasticity of a straight line is immediately recoverable, some is recoverable over time, and in some extremes, some is never recoverable. Enter the knots variable; and we have part that is now a single sue, and not recoverable until we reset/ relax the line/ untie.

The elasticity can absorb and or store the dynamic force. When it absorbs it; it converts the energies to frictions / heat i believe; both coming into and going out of stretched by scrubbing fibers etc. The knot then can do similar, only force friction by scrubbing and pulling slack from some turns to force through the scrubbing and some slipping and some choking /compressing on a rope host. Like a double fishermans as a bend, but spread apart some. It can slip together under heavy load, draw from the coils, compress the line the turns are on etc. the more turns, the more of a pool of slack to drag through frictions and compress on the line etc. all orchestrating different levels of absorption of forces; to add to and compliment the line's inherent dynamics. This is another case for a Triple Scaffold as a termination over a Bowline etc.; and how a Double Bowline can be not only stronger than a Bowline, but also better in a dynamic circumstance; but less dramatically after the first dynamic loading etc.

To me, this is like you are on a steel cable, and the line itself has such and such properties that add a piece of shock absorbing rubber at the end, then the knot properties add another etc. The more the mix, the more Nature is given to choose from combinations immediately on the spot to give Her magical minimum loading to all of the connected points of self, load, anchors and supports etc.

Orrrrrrrr something like that.

[TheTreeSpyder]

Nick; ya might try a different browser; have tried to duplicate your problem and found that maybe some rough times with Firefox?? Or, might try downloading rather than opening the file?

To me, ropes are one of our standard, multipurpose tools; and i try to understand as much about them as possible. Many times that involves just doing my best with them; to see were that leads!