# Static or Dynamic???



## ForTheArborist (Dec 4, 2009)

*Static or Dynamic??? Vote*

I've been taught that a static line is the way to go for climbing because you don't want the rope stretching out on you as you climb it. I assume that the dynamic one is the way to go when rock climbing because you really don't climb the rope. It is just there to fall on. When you finally come tout with it, it may flex instead of jerk you as a static line would. 

As an arborist the rope is tout to you already, so there is no use for the flexibility. A comprimise in tensile strength to have a flexible rope is not worth anything to the arborist, so the stronger static line is more desired.

Am I getting this right? I've never known any arborist to use a dynamic rope for climbing. 

The reason I ask all of a sudden is because I met up with a guy around here that used to be in the arborist gear sales. Now he just fixes chippers and stuff after he stopped doing tree work himself. He tried very hard to sell me on the idea that dynamic rope is for tree climbers while static is more for rigging and towing. I doubt he was telling me right. What do you say?


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## TreeW?rx (Dec 4, 2009)

He was correct. And you are getting your terms crossed up. Static rope is what you use for SRT or DRT (Footlocking), a dynamic rope is what is used for DdRT, as in Friction hitch climbing. A dynamic rope needs to be more fllexible, it is moving as you climb. Also, you dont want to much flex in a rope that you rig with and as little as possible in something that you would winch with. Think Steele cable, it doesent stretch much at all.

Figure out what you want to use the rope for then go shopping.


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## mattfr12 (Dec 4, 2009)

You can climb on either. I have. static lines are alot easier to cut tho because all of the stretch is out of the rope. dynamic is a little more difficult to cut. saftey blue is a dynamic rope i do believe. the bartlett office i worked in made a policy that we couldnt use static ropes anymore because of how little of a cut causes it to fail.


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## ForTheArborist (Dec 5, 2009)

TreeWurx, I remember now. Somebody told me that it is extra difficult to climb on dyna rope because as you try to pull your self up before moving the frict hitch up, it stretches on you. In the case of static rope there is no strethc of course. 

Matt12 says their company has mandated only dyna rope use, so... I better keep asking around. I've always felt wierd about breaking my legs and stuff from out of a tree. I better make sure I'm on the best strings. :yoyo:


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## davej (Dec 5, 2009)

If arborist rope stretches at all we complain about it. Dynamic rope is designed to stretch.


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## treevet (Dec 5, 2009)

mattfr12 said:


> saftey blue is a dynamic rope i do believe. the



the first safety blue put on the market was a 3 strand and it was stretchy. coming from the manilla which is static nobody liked it. then they developed the 16 strand braid, static, which everyone threw their manilla away for esp. because the touted interior safety strand (blue) they said if you cut your rope it would hold you up. wouldn't want to test it tho.


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## treesquirrel (Dec 5, 2009)

I think the dynamic ropes you are speaking of are those specifically for rock climbing that must catch a falling climber.

Each type of rope has its own stretch factors but really stretchy ropes are typically for recreational use. Check the sherrill tree site for stretch tables.


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## John Paul Sanborn (Dec 5, 2009)

treesquirrel said:


> I think the dynamic ropes you are speaking of are those specifically for rock climbing that must catch a falling climber.
> 
> Each type of rope has its own stretch factors but really stretchy ropes are typically for recreational use. Check the sherrill tree site for stretch tables.



What he said.

The cordage industry term is _modulus of elasticity_. Give one of our ropes to a rock climber and he will call it static, since they use the rope for fall prevention only. What we do is a type of aid climbing to them.

Compare it to a Kernmantle static line used by cavers and you will see the stretch in it. Cavers will descend 100 feet or more into sink holes and the elasticity of our rope will come through, same thing with SRT where it is run over several limbs and down to the base of the tree. I set my lardass on 200 ft of arborist rope and it is like climbing on a bungee cord. 

If you are climbing small trees on a traditional system, then a basic arborist rope is all you need. It has been desigend to have a modulus that will help if we have a light fall, but not elongate during normal work. Velocity is my favorite rope, but I do SRT on KMIII static.


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## ForTheArborist (Dec 5, 2009)

Thanks all


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## ATH (Dec 5, 2009)

Static for tree climbing. We should never by putting a dynamic load on our climbing line (or on our saddles that are not deisgned for dynamic loads) so dynamic rope offers us no advantage. All of the stretch and none of the 

Dynamic for rock climbing. A rock climber is using the line to catch him when he falls. If he falls 6-8 feet on a static line, that can snap something (other than the rope...). A line with a little stretch makes that a more reasonable fall.

Rigging tree parts: should be designed as a system and the rope needs to meet the system. If you are often placing a dynamic (moving) load on the line, so we don't want the static line to "grab" it without any give - too much stretch on the rope.


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## Norwayclimber (Dec 6, 2009)

Just to add a little perspective: A rockclimbing rope (dynamic) will stretch 30-40% when loaded at maximum fall.


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## treevet (Dec 6, 2009)

The friction device allows the give on the rope to lessen stress without the recoil you would get from a dynamic. If there was recoil up there it could get scary.


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## rbtree (Dec 7, 2009)

Norwayclimber said:


> Just to add a little perspective: A rockclimbing rope (dynamic) will stretch 30-40% when loaded at maximum fall.



Actually the stretch at break is closer to 70%.


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