remote suspension/spanline removal

letigre · 4th April 2008, 01:52 AM

hey guys! ive got a hellish climb on monday, just wondering if anyone has some advice and or literature on remote suspension/spanline setups?

ok, so heres the story; angophora costata (syd red gum) 37m tall multi-leadered beast, dead wood and crown inspect (no probs) and a hellish 15m branch walk out into space with a high point that doglegs out away from the branch. so moral of the story is i have no rigging point (except off itself and there isnt quite the clearance) and no real high point: i can get half way out the branch (just by looking at it) and it is possible to us a secondary line through the end of the branch to "skywalk" out (however seriously labour intensive and time consuming not to mention seriously uncomfy).

so, my idea is; set up a remote suspension point/spanline (flying fox if you will) between the specimen and an adjacent tree. sending the rope through pulley and sling set ups and going back to the ground, tightening with a friction drum on one end and tied off with a prussick set up on the other. my climbing system would run off a micropulley on that rope, hence suspending me directly above the branch (and the house).

would be a good time to apologise for not having any fotos!! will get some up on monday night!

so here a problem arises; its a 30m gap from tree to tree and i have no idea of the physics involved and wether its safe or not! i figure speedlines are set up that long all the time and i dont weigh nearly as much as a decent speedline load so there shouldnt be an issue.

what do you guys think?

JohN Dee · 4th April 2008, 02:36 AM

It sounds good to me.

Only problem I could think of with physics and tree biology would be if you tied the spanline to a leader with a bad inclusion. I reckon the side loading would probably tear it out if you were unlucky. Otherwise treat them both like any other normal TIP.

Just thought of something. Your pulley that your life line will be going through, will you be sliding accross the line while it's taut or will you be using the spanline as a V?

Here are some diagrams to help explain my questions:

Only problem I see with this is that bloody pulley is gunna slide everywhere when you want a nice static position whilst cutting...

Seems good for work positioning only problem is if you don't have attentive groundies... You gotta wait around for them to help you move...

Good luck mate and take LOTS of pics, will be very interesting to see.

P.S What part of Sydney you working in?

Treelore · 4th April 2008, 03:36 AM

Done some work like this with Lightning struck trees. Used a tandem pulley attached a second line so that it could be controlled by a groundworker adjusting how far along you or the pulley can move. It can also be installed from the ground with a long enough rope tied at both ends to the ground or another tree. This can also be tensioned with a block and tackle so that there is less dynamic movement in the rope above. The other option maybe twin lowering lines and twin lowering devices from either tree to lower in a V with a dogline to swing branch clear. probably an easier setup.

PTC · 4th April 2008, 04:10 AM

That sounds like fun

I think your gonna need lots of rope!

Quote:

its a 30m gap from tree to tree and i have no idea of the physics involved and wether its safe or not!

Well, im not a physicist but I dont think it matters how far away the tie in points are as long as they are strong enough to withstand the side loading.
All your really adding to the system is rope.

Also, id be cautios when tensioning the system with a drum

Any clues to the location of this tree? A 37m red gum would be quite a sight!

Ekka · 4th April 2008, 05:03 AM

Quote:

Originally Posted by letigre

angophora costata (syd red gum)

Common name is Smooth barked apple. Looks similar to spotty gum but reddish tinge to bark and leaves are opposite.

Quote:

Originally Posted by letigre

so, my idea is; set up a remote suspension point/spanline (flying fox if you will) between the specimen and an adjacent tree. sending the rope through pulley and sling set ups and going back to the ground, tightening with a friction drum on one end and tied off with a prussick set up on the other. my climbing system would run off a micropulley on that rope, hence suspending me directly above the branch (and the house).
....

what do you guys think?

DO NOT USE A PRUSSIK! A tensioned line line that will experience 5x your weight (when just hanging there doing nothing) at the terminal ends. If you are suspended from that line DRT then at times you could be doubling your weight.

100kg load might become 200kg. Which puts 1000kg onto the ends of that tensioned overhead flyfox line. Prussik and even ascenders etc are know to slip and tear sheaths of rope above 600kg of force. The tension has to be held with a friction drum etc and backed up perhaps with two prussik's. One end obviously tied off.

But a 30m span is only 15m each side. Dual high points may give more maneuverability.

newguy18 · 4th April 2008, 07:50 AM

Can you rig a setup like this one?
YouTube - Two Tie-in Points for Hazardous Removals

JohN Dee · 4th April 2008, 07:11 PM

Quote:

Originally Posted by Ekka

Common name is Smooth barked apple.

Lol down here it is either, but more referred to like Sydney Red Gum. just like your QLD Brushbox.. Down here it's just brushbox, mate.

But who are we to decide the commen name of a tree? There are alot of variations of commen names going from community to community.

Quote:

Originally Posted by Ekka

But a 30m span is only 15m each side. Dual high points may give more maneuverability.

That would really depend on how high his high points are, and they don't sound like much... From my experience, from a high point, you only have upto about a 45 degree angle from it until it stops full supporting you and your weight is actually on the branch. If he has to go past that 45 degree angle it's gunna be mighty hard to adjust his friction hitches.

PTC · 4th April 2008, 11:26 PM

Quote:

DO NOT USE A PRUSSIK! A tensioned line line that will experience 5x your weight (when just hanging there doing nothing) at the terminal ends. If you are suspended from that line DRT then at times you could be doubling your weight.

100kg load might become 200kg. Which puts 1000kg onto the ends of that tensioned overhead flyfox line. Prussik and even ascenders etc are know to slip and tear sheaths of rope above 600kg of force. The tension has to be held with a friction drum etc and backed up perhaps with two prussik's. One end obviously tied off.

I dont know of any literature explaining the forces involed in this type of set up. Does the 5x the load come from pretensioning the line with a drum?

If so, does this mean that if you use a line that is only pretentioned by hand that the forces on the tie in points would be closer to double your weight?

Similar forces to a set up with climing line runninig through a pulley that is being held up by another rope that runs over a branch and is tied off at the base?

Ekka · 5th April 2008, 04:44 AM

Quote:

Originally Posted by PTC

I dont know of any literature explaining the forces involed in this type of set up. Does the 5x the load come from pretensioning the line with a drum?

Yes, it all depends on the angle of the rope, less tension means the ropes angle changes.

Quote:

Originally Posted by PTC

If so, does this mean that if you use a line that is only pretentioned by hand that the forces on the tie in points would be closer to double your weight?

Closer yes, but still more than double.

Quote:

Originally Posted by PTC

Similar forces to a set up with climing line runninig through a pulley that is being held up by another rope that runs over a branch and is tied off at the base?

No, different concept, that has force multipliers in the same line, here we have force multipliers depending on the angle of the line.

When a crane has two chians to lift a beam, as the angle of the chains attached to the beam changes so does the force on the each chain. At 120 degrees the chains each experience the same weight as the load, you'll never see a crane go past that either.

Here's an easy experiment for you.

Got a good spring scale, maybe 25kg one?

Get a rope and tie it to your fence at say middle rail 1m ht.

Tie say a 3kg to 5kg weight on the rope. On the other end of the rope (weight in the middle) have the spring scale.

Slowly lift the weight, starting straight up, like double rope. Note the weight on the scale.

Now start pulling away from the fence and have the weight on the rope inline with a tight rope, check the scale. 5x

PTC · 5th April 2008, 05:40 PM

Thanks Ekka, good explanation

So if we took your diagram, extended the rope from the blue scales over a branch and tie it of at the ground, can we calculate the load on the branch (assuming we know the load at the scales) or do we need to factor in the angle of the rope again?

apologies for lack of diagrams

letigre · 5th April 2008, 11:35 PM

thanks for the helpful tips guys! heres some answers to some of your questions.

Just thought of something. Your pulley that your life line will be going through, will you be sliding accross the line while it's taut or will you be using the spanline as a V?

yeah cheers for the import john, i would use a v so i could use the dip to position myself. i def hear what your saying, having a tautline could be a pain.

P.S What part of Sydney you working in?[/quote]

all over really, work for a company called sydney arbor trees based in botany and run by a guy named craig young. the tree in question is in hunters hill.

That would really depend on how high his high points are, and they don't sound like much... From my experience, from a high point, you only have upto about a 45 degree angle from it until it stops full supporting you and your weight is actually on the branch. If he has to go past that 45 degree angle it's gunna be mighty hard to adjust his friction hitches.

yeah the high points are on the verge of being useful in some sort of application as newguy suggests. i know what you mean john, you high point starts working against you, dragging you into the ground. will suss it out again tomorrow morning, trees have a tendency to become much larger and difficult that they actually are after leaving the inspection.

DO NOT USE A PRUSSIK! A tensioned line line that will experience 5x your weight (when just hanging there doing nothing) at the terminal ends. If you are suspended from that line DRT then at times you could be doubling your weight.

thanks for you imput ekka, alway come through with the goods! hear what your saying and will definately look into some other system. cheers for the explaination and the diagrams too.

think your gonna need lots of rope!

hell yeah ptc. already got two lengths of 200ft and a 150fter!

Any clues to the location of this tree? A 37m red gum would be quite a sight!

its on private property in hunters hill. i could be wrong on the height but its at least 30m tall. the branch ive got to remove is at least 4 metres above a two story gabled house thats piered (pole house). ill throw my rope down when im at the top and snap a pic for you!

Used a tandem pulley attached a second line so that it could be controlled by a groundworker adjusting how far along you or the pulley can move. It can also be installed from the ground with a long enough rope tied at both ends to the ground or another tree. This can also be tensioned with a block and tackle so that there is less dynamic movement in the rope above. The other option maybe twin lowering lines and twin lowering devices from either tree to lower in a V with a dogline to swing branch clear. probably an easier setup.

cheers treelore, thats pretty much the conclusion ive come to. will take photos and see what you think.

Ekka · 6th April 2008, 01:31 AM

Quote:

Originally Posted by PTC

Thanks Ekka, good explanation

So if we took your diagram, extended the rope from the blue scales over a branch and tie it of at the ground, can we calculate the load on the branch (assuming we know the load at the scales) or do we need to factor in the angle of the rope again?

apologies for lack of diagrams

Angles always make a difference when there's loads applied.

You can have a tight rope horizontal across say a river, have say 500kg weight hanging in middle, like a flat speed line. The amount of force or weight on each end of that rope is the same, however if the rope was the other extreme which is vertical all that 500kg of load would be on the top knot.

As the angle of the line changes so does the force at either end.

If a horizontal rope was pretensioned with say 250kg of force, then ole mate who weighs 100kg is added hanging in the middle of that rope, what force would be on each end?

750kg

You already have 250kg of tension, ole mate is going to weigh 5x due to the factor here (roughly) so ole mate is adding 500kg of force onto the ends of the rope. I do say roughly coz the rope does get a slight dip in it when load is added.

This is part of the reason why you shouldn't dump loads onto a tensioned speed line.

Here's a good simulator, drag the blue diamond along to 100kn and look at the numbers on the end, and that is with a 30 degree deflection and no pre tension.

TAG : Tyrolean traverse load simulator

PTC · 6th April 2008, 05:09 AM

intersting simulator

conclusions:

the vertical load stays at 5x the load even when you change the angle of the rope.

the horizontal load varies depending on the force used to pretension the line

most climbing ropes arnt strong enough for this type of set up if you are using a 10:1 safety factor

PTC · 6th April 2008, 05:14 AM

still not sure why its 5x ?

Ekka · 6th April 2008, 05:56 AM

It's one of those things.

Like pi=3.1416

gravity=9.8ms2

4th April 2008, 01:52 AM	#1 (permalink)
letigre Gettin' motoring Join Date: Aug 2007 Location: Australia Posts: 29	remote suspension/spanline removal hey guys! ive got a hellish climb on monday, just wondering if anyone has some advice and or literature on remote suspension/spanline setups? ok, so heres the story; angophora costata (syd red gum) 37m tall multi-leadered beast, dead wood and crown inspect (no probs) and a hellish 15m branch walk out into space with a high point that doglegs out away from the branch. so moral of the story is i have no rigging point (except off itself and there isnt quite the clearance) and no real high point: i can get half way out the branch (just by looking at it) and it is possible to us a secondary line through the end of the branch to "skywalk" out (however seriously labour intensive and time consuming not to mention seriously uncomfy). so, my idea is; set up a remote suspension point/spanline (flying fox if you will) between the specimen and an adjacent tree. sending the rope through pulley and sling set ups and going back to the ground, tightening with a friction drum on one end and tied off with a prussick set up on the other. my climbing system would run off a micropulley on that rope, hence suspending me directly above the branch (and the house). would be a good time to apologise for not having any fotos!! will get some up on monday night! so here a problem arises; its a 30m gap from tree to tree and i have no idea of the physics involved and wether its safe or not! i figure speedlines are set up that long all the time and i dont weigh nearly as much as a decent speedline load so there shouldnt be an issue. what do you guys think?

4th April 2008, 03:36 AM	#3 (permalink)
Treelore Banned Join Date: Feb 2008 Location: Brisbane Posts: 117	Re: remote suspension/spanline removal Done some work like this with Lightning struck trees. Used a tandem pulley attached a second line so that it could be controlled by a groundworker adjusting how far along you or the pulley can move. It can also be installed from the ground with a long enough rope tied at both ends to the ground or another tree. This can also be tensioned with a block and tackle so that there is less dynamic movement in the rope above. The other option maybe twin lowering lines and twin lowering devices from either tree to lower in a V with a dogline to swing branch clear. probably an easier setup.

4th April 2008, 07:50 AM	#6 (permalink)
newguy18 Tree World Icon Join Date: Jun 2007 Location: Live Oak Florida home of the crapiest trees you will ever see. Posts: 2,185	Re: remote suspension/spanline removal Can you rig a setup like this one? YouTube - Two Tie-in Points for Hazardous Removals __________________ Have your say join us today. http://www.youtube.com/watch?v=Xzkd_m4ivmc http://www.youtube.com/watch?v=Xzfzb...eature=related http://www.youtube.com/watch?v=x-OqK...eature=related

5th April 2008, 05:40 PM	#10 (permalink)
PTC Gettin' motoring Join Date: Oct 2007 Location: Sydney Posts: 16	Re: remote suspension/spanline removal Thanks Ekka, good explanation So if we took your diagram, extended the rope from the blue scales over a branch and tie it of at the ground, can we calculate the load on the branch (assuming we know the load at the scales) or do we need to factor in the angle of the rope again? apologies for lack of diagrams

5th April 2008, 11:35 PM	#11 (permalink)
letigre Gettin' motoring Join Date: Aug 2007 Location: Australia Posts: 29	Re: remote suspension/spanline removal thanks for the helpful tips guys! heres some answers to some of your questions. Just thought of something. Your pulley that your life line will be going through, will you be sliding accross the line while it's taut or will you be using the spanline as a V? yeah cheers for the import john, i would use a v so i could use the dip to position myself. i def hear what your saying, having a tautline could be a pain. P.S What part of Sydney you working in?[/quote] all over really, work for a company called sydney arbor trees based in botany and run by a guy named craig young. the tree in question is in hunters hill. That would really depend on how high his high points are, and they don't sound like much... From my experience, from a high point, you only have upto about a 45 degree angle from it until it stops full supporting you and your weight is actually on the branch. If he has to go past that 45 degree angle it's gunna be mighty hard to adjust his friction hitches. yeah the high points are on the verge of being useful in some sort of application as newguy suggests. i know what you mean john, you high point starts working against you, dragging you into the ground. will suss it out again tomorrow morning, trees have a tendency to become much larger and difficult that they actually are after leaving the inspection. DO NOT USE A PRUSSIK! A tensioned line line that will experience 5x your weight (when just hanging there doing nothing) at the terminal ends. If you are suspended from that line DRT then at times you could be doubling your weight. thanks for you imput ekka, alway come through with the goods! hear what your saying and will definately look into some other system. cheers for the explaination and the diagrams too. think your gonna need lots of rope! hell yeah ptc. already got two lengths of 200ft and a 150fter! Any clues to the location of this tree? A 37m red gum would be quite a sight! its on private property in hunters hill. i could be wrong on the height but its at least 30m tall. the branch ive got to remove is at least 4 metres above a two story gabled house thats piered (pole house). ill throw my rope down when im at the top and snap a pic for you! Used a tandem pulley attached a second line so that it could be controlled by a groundworker adjusting how far along you or the pulley can move. It can also be installed from the ground with a long enough rope tied at both ends to the ground or another tree. This can also be tensioned with a block and tackle so that there is less dynamic movement in the rope above. The other option maybe twin lowering lines and twin lowering devices from either tree to lower in a V with a dogline to swing branch clear. probably an easier setup. cheers treelore, thats pretty much the conclusion ive come to. will take photos and see what you think.

6th April 2008, 05:09 AM	#13 (permalink)
PTC Gettin' motoring Join Date: Oct 2007 Location: Sydney Posts: 16	Re: remote suspension/spanline removal intersting simulator conclusions: the vertical load stays at 5x the load even when you change the angle of the rope. the horizontal load varies depending on the force used to pretension the line most climbing ropes arnt strong enough for this type of set up if you are using a 10:1 safety factor

6th April 2008, 05:14 AM	#14 (permalink)
PTC Gettin' motoring Join Date: Oct 2007 Location: Sydney Posts: 16	Re: remote suspension/spanline removal still not sure why its 5x ?

6th April 2008, 05:56 AM	#15 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 5,664	Re: remote suspension/spanline removal It's one of those things. Like pi=3.1416 gravity=9.8ms2