Max Weight On A Speedline?

[Torquin]

I am bidding on a Poplar removal, as part of a 6 tree job. This Poplar is about 75+ ft. tall and about 32" DBH. It is 2' from the ground-level deck, and 2' from the pond/water garden, which ends about 6" from the deck. The pond is in the way of my access to the tree from the side where the bucket truck will have to come in, so I will have a climber take out the top, at least, and down to where I can access it with the bucket truck. Behind it, a distance away, is a sandbox, swing set, and plenty of other trees that I am not taking down. The opposite side of the Poplar has a little bit of working area before you get to the fence. I can probably get the tractor in there and turn around, but it will be tight.
I have plenty of room on the other side of the pond, parallel to the back of the house.
I am thinking about speedlining the pieces down, over the pond to the other side of the yard.
I am calculating the weight of the wood, at the largest point, to be 221 lbs per foot. I am wondering how big I can go with the pieces of the spar once I get the top out of it.
Of course this depends on my equipment, I know, but let's say in a perfect world, with my 3/4" bull rope, how big can I expect to be reasonable when cutting this trunk? I have a 3/4" bull rope and two 1/2" ropes, one a former climbing rope turned to rigging rope.
The speedline will be tied off to the trunk, just below the cut.
I figure I will need to cut it while attached to another rope, attached to the porta-wrap, so that absorbs the shock load when it falls, then connect it to the speed line and let it down, probably using the rope and porta-wrap I used for the shock absorbing.
The perfect length would be 8'6", so I can use it for the sawmill, but safety comes first and I'll take it out in 12" lengths if that's what's necessary. The 8'6" length will be close to 2000 lbs, but I don't know if I can count on a speedline to support that kind of weight, or the shock load on the block and porta-wrap for that weight.
Would I be better off cutting small enough pieces that the speed line could absorb the shock as well as transport it down?
The other thing about the speedline is it will have to go over the bucket truck to get down to the ground.
If my pieces get that small I can just drop them on the other side of the tree, away from the pond, but then I have to get the pieces out of there somehow, and that's why the speedline idea came up in the first place.

Thanks,
Chris

 

[John Paul Sanborn]

It sounds to me that you will be using the speedline as a traverse, and the control line to catch the load.

So the control line needs to be the beefier rope, with a 10:1 SWL reduction you need a 20000# rope for the initial rigging.

I use a 5:1 reduction for non-shock-loading applications, so that is a 10000# SWL on the speedline, though you need to take your tensioning force into the equation too, so do not get it too tight.

The way I've done is to bomb the load onto a porty, and have the speedline on a Hobbs or GRCS so it can be attached to the load then tensioned.

 

[bigredd]

Those 1/2" tyrolean pulleys are not what you need for moving large pieces of spur on a zip line. I had a similar Poplar Tree in my yard, but with double trunk (each 30" @ base), 105' high and no landing area below. We used a similar setup as you describe and easily moved 8+ foot sections of 22" spur down the zip line. We used 5/8" rope for both zip line and porta wrap.

Recommend using a 3" rigging ring through the zip line. Then connect a loopie/block below the cut and attach that line to the ring. Also attach a sling to the ring and tie the sling to the spur above the cut. When the spur drops, the shock load is shared by both ropes and the porta wrap controls the decent. When the zip line slope gets too low you may need to attach a tag line to the ring to help move it down the line.

Good luck and stay safe.

 

[StihlRockin']

I say go the safer route and work with smaller pieces. Yes it would be nice to have the ideal pieces you can work with, as you get the value there and it is quicker to work with overall, but bid the job, get it done safe and move on.

StihlRockin'

 

[pdqdl]

Is that a dead poplar? Is it's strength compromised in some other way?

Keep in mind that a long speedline with a heavy load will put enormous side-load on your standing spar. It won't help you any to use a stronger rope if it helps you pull the tree over with you in it.

I don't speed line much, but I find that I can move smaller pieces much faster. I would say go lighter and faster. Lighter materials can be left unrestrained by a tether line to truly ZIP to the downhill end of the speedline.

 

[bigredd]

:agree2:

I say go the safer route and work with smaller pieces. Yes it would be nice to have the ideal pieces you can work with, as you get the value there and it is quicker to work with overall, but bid the job, get it done safe and move on.

StihlRockin'

Always side on safety. We were lucky to give away some of our poplar trunk to a mill. Very hard to find a mill willing to accept urban wood around here, and Poplar makes terrible firewood. It pops and smokes, and is only usable for outdoor fire pits. I'd plan on disposal in your bid.

 

[Torquin]

The Poplar is alive and well. The guy has a forest in his back yard, and the tops have already broken out of a few of the trees he wants me to take out. I think this one is pre-emptive, since it is the closest to the house.
I can piece this one out smaller as I have 4 other Poplars I'm taking out and my sawmill buddy will be happy with those.
If you do a zip-line, do you just tie a piece of string or small rope to the trolley to haul it back up?

Thanks,
Chris

 

[bigredd]

The Poplar is alive and well. The guy has a forest in his back yard, and the tops have already broken out of a few of the trees he wants me to take out. I think this one is pre-emptive, since it is the closest to the house.
I can piece this one out smaller as I have 4 other Poplars I'm taking out and my sawmill buddy will be happy with those.
If you do a zip-line, do you just tie a piece of string or small rope to the trolley to haul it back up?

Thanks,
Chris

With the system I described, the porta wrap line pulls the ring back to the block.

 

[md_tree_dood]

If you can access it with a bucket truck, you can access it with a crane. 4+ picks, the tree is done, in an hour instead of all day with your zip line setup. Why go fancy when you can go safe, fast, efficient, and fun? Not to mention you can do the other 4 with the crane, and spend your afternoon counting on the money you made, go for a 5k run since you won't be tired, maybe sharpen some saws, grill out, you get the idea.....

 

[pdqdl]

...
If you do a zip-line, do you just tie a piece of string or small rope to the trolley to haul it back up?

Thanks,
Chris

I just attach the speed line to the tree close to where I am working, usually with a sturdy carabiner for ease of moving it quickly. I go up the tree with about 10 nylon loopies, each with an inexpensive (but sturdy) 'biner. Loopie to the branch, clip to the rope, signal ground men to snug up the rope, cut!

The branch flies down to the ground men, and I am already rigging the next cut with another loopie. The ground men only need to loosen the speed line when I have cleaned out my location, and need to move it. 500lb branches or logs are actually easier than lowering in the traditional way, with less shock loading. About every 8 cuts, send the loopies back up to me.

If you have a real long run to the end of your speedline, you will probably need to have a pulley and a retrieval/control line, as the descent angle might not be enough to finish the run to the ground.

 

[outofmytree]

I just attach the speed line to the tree close to where I am working, usually with a sturdy carabiner for ease of moving it quickly. I go up the tree with about 10 nylon loopies, each with an inexpensive (but sturdy) 'biner. Loopie to the branch, clip to the rope, signal ground men to snug up the rope, cut!

The branch flies down to the ground men, and I am already rigging the next cut with another loopie. The ground men only need to loosen the speed line when I have cleaned out my location, and need to move it. 500lb branches or logs are actually easier than lowering in the traditional way, with less shock loading. About every 8 cuts, send the loopies back up to me.

If you have a real long run to the end of your speedline, you will probably need to have a pulley and a retrieval/control line, as the descent angle might not be enough to finish the run to the ground.

So the krab is running down the speedline?

Any friction/heat issues here?

 

[southsoundtree]

This isn't an answer to your question, but an option in its place.

Can you use a drift line/ load-transfer line in the place of the speed line to move it to a safe landing zone? For pieces that large, you will need to drop them a ways to decelerate, climb down, hook on speedline, climb back up to detach the speedline/ lower speedline for next cut after each piece is landed.

With a load transfer line, you just will need to set up a block in an adjacent tree once, if you can drift the logs into a tractor accessible area.

 

[pdqdl]

Yes. Krab sliding down the line. I have never noticed any heat issues, but it is certainly possible.

If I was sending down larger limbs than 500 lbs, I think I would be concerned, and I would add a pulley to carry the load, and step up to a control line that would share the load and do the braking.

Long traverses with little vertical drop obviously won't work unless you add a pulley to help carry the load, maybe even a tag line to haul the load in the direction needed.

 

[teacherman]

Yes. Krab sliding down the line. I have never noticed any heat issues, but it is certainly possible.

If I was sending down larger limbs than 500 lbs, I think I would be concerned, and I would add a pulley to carry the load, and step up to a control line that would share the load and do the braking.

Long traverses with little vertical drop obviously won't work unless you add a pulley to help carry the load, maybe even a tag line to haul the load in the direction needed.

Could you put a bit of slack in the speedline to slow the pieces down if using pulleys?

 

[TheJollyLogger]

No, that won't slow it down. Wow, old thread.

 

[pdqdl]

Could you put a bit of slack in the speedline to slow the pieces down if using pulleys?

It all kind of depends upon which rope you are calling "the speedline". If you are just using one rope to convey cut off limbs to the ground, they will come down faster if you give them more slack. The more vertical the drop, the faster they go, right?.

Loosening the rope will have a different effect, however. When the speedline has more slack, the lateral forces applied to the two endpoints on the rope is diminished. If you load a really tight speedline with a heavy load, it will be much more likely to break out the top of the tree. Furhtermore, it seems unlikely that there will be a possible method to predict the forces applied or the breaking strength of a tree. So... don't get too aggressive!

 

[TheJollyLogger]

Here's a Mythbusters short to illustrate the physics. As far as the forces, they can be calculated, but... the one variable that's difficult to factor is the lateral strength of the stem, but those lateral forces can be significant. Always better to go small, and go home...

 

[pdqdl]

Ahh... You know me. A technical issue, and I have to jump in.



Now here is the problem: these curves are all drawn upon an unloaded object accelerating by gravity and according to its mass and physical shape. Consider, for example, that a disk rolls much slower down an inclined plane than does a sphere. Both fall vertically at the same rate, providing air resistance is not involved.


Unfortunately, your brachistochrone curves are largely unrelated to the acceleration curve of a tiny pulley being dragged downward by a relatively huge branch/log. At that point, the acceleration sideways and the wind resistance is a much greater component of the "time to bottom" calculation. I think that you will discover that the closer the slope is to a constant slope without curvature, the acceleration remains constant, and the terminal velocity will be set by whatever friction is present in the system. The greater is the lateral component of that system, the more likely it is that a straight line will be fastest, and also involve greater force applied to the anchor points on both ends.

By the way:

• why does the hoop get there last?
• If all the three objects have the same mass, which one hits the endpoint with the most energy?
  • Same question, but let's make sure we consider friction in the equation.