I like to think of my foreman as "old school" when it comes to trying new equipment. We have had this discussion before and I would like some other opinions on the matter. when using a rope to pull a tree over we use a three strand twisted soft lay rope, he likes it for the stretch. I'm trying to get him to go to a samson bull rope or something similar. my question is do you want stretch in a rope or not?
ropes?
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Stumper
One Man Band
You'll find divergent opinions. I like stretch in a tag line for pulling trees-I frequently work alone and a pretensioned dynamic/semi-dynamic line allows for a take-up/bungee action so that a small movement in the tree top doesn't slacken the rope completely. The anchored line can continue to pull for a few feet. Static lines work extremely well when someone or something is taking up the slack as the top moves. It all works if we work it right.:angel:
Same in pulling a truck out, work the stretch and have it pull in addition to the pull of the pull vehicle (like Brian has said before).
But, used differently, and not purposely loaded effectively etc. can change the effect. Placing more of same line in the works and/or line choice that is really worked by loading (percentage of tensile strength used) can also adjust the amount of the effect.
Or, soemthing like that,
:alien:
But, used differently, and not purposely loaded effectively etc. can change the effect. Placing more of same line in the works and/or line choice that is really worked by loading (percentage of tensile strength used) can also adjust the amount of the effect.
Or, soemthing like that,
:alien:
Tom Dunlap
Addicted to ArboristSite
Using a low-stretch rope allows us to put the tension in the tree not the rope. Why would you want to have the rope stretch? If you do, more energy goes into the rope less into pulling the tree.
When I use a pullover rope, I put my FOS, Friction On Site, anchor on the other tree, snub it off, put on the compression tackle as a piggy back. Then I tension the rope as much as I feel is needed. Make the face cut. Tension some more after making the face. Before starting the back cut I run the compression tackle out as far as it will go. As the back cut is made the CT can be tightened up, keeping the line tight.
Tom
When I use a pullover rope, I put my FOS, Friction On Site, anchor on the other tree, snub it off, put on the compression tackle as a piggy back. Then I tension the rope as much as I feel is needed. Make the face cut. Tension some more after making the face. Before starting the back cut I run the compression tackle out as far as it will go. As the back cut is made the CT can be tightened up, keeping the line tight.
Tom
Stumper
One Man Band
See, I told you there are divergent opinions.
Tom, storing energy in the rope IS the point-instead of all those retensions of the pretension you can do it all in one swell foop. ( It really does all work-if the arbo knows what he is doing to the tree with the rope of choice)
Tom, storing energy in the rope IS the point-instead of all those retensions of the pretension you can do it all in one swell foop. ( It really does all work-if the arbo knows what he is doing to the tree with the rope of choice)
SteveBullman
User Formerly known as stephenbullman
slightly off topic.....we have a thick piece of hemp rope, guess it must be about 35-40mm we have used on occassion for pulling trees over.
always amazes me when you pull it by hand, with every effort, you can't get the slack out of the rope, yet theres heaps of energy in the rope to easily pull the tree over
if you're getting me
always amazes me when you pull it by hand, with every effort, you can't get the slack out of the rope, yet theres heaps of energy in the rope to easily pull the tree over
if you're getting me
Dadatwins
Addicted to ArboristSite
I am with Stumper on having stretch in a pull line. I like the fact that the tensioned rope will still 'pull' because it has been stretched even if the 'puller' groundman does not take up the slack quick enough as the tree starts to come over. Or when by myself I have the extra 'pull' already in the line by stretching it.
Just my opinion for what its worth.
Just my opinion for what its worth.
rumination
ArboristSite Guru
Yup, I'm in agreeance. Especially when working alone, the stretch in the pull line can be your friend.
Tom Dunlap
Addicted to ArboristSite
do you understand what the stretch specifications mean for rope? If there is a rope with X5 stretch listed in it's spec sheet that doesn't mean that if will stretch a certain amount over it's whole strength range.
Stretch is related to a percentage of the breaking strength. Some ropes stretch a lot in the lower end of the strength range then don't stretch anymore as they approach breaking strength. The plotted graphs are curved for all ropes. Until you understand how to compare the graphs you really can't say that a particular rope is better for a certain application. Stretch is probably one of the least understood characteristics of rope.
Rope materials and the way the fibers are woven makes a big difference too. One reason three strand "stretches" so much is that the fibers move around into a more linear relationship as they're loaded. If the same fibers were taken and not woven, the rope would stretch less.
I'll stick with using double-braids which have a better performance curve than three strands. There is still plenty of stretch in DB ropes to work with. Using the high mod ropes really puts you close to a no-stretch rope.
Tom
Stretch is related to a percentage of the breaking strength. Some ropes stretch a lot in the lower end of the strength range then don't stretch anymore as they approach breaking strength. The plotted graphs are curved for all ropes. Until you understand how to compare the graphs you really can't say that a particular rope is better for a certain application. Stretch is probably one of the least understood characteristics of rope.
Rope materials and the way the fibers are woven makes a big difference too. One reason three strand "stretches" so much is that the fibers move around into a more linear relationship as they're loaded. If the same fibers were taken and not woven, the rope would stretch less.
I'll stick with using double-braids which have a better performance curve than three strands. There is still plenty of stretch in DB ropes to work with. Using the high mod ropes really puts you close to a no-stretch rope.
Tom
Stumper
One Man Band
Yes Tom. Knowing our ropes stretch specs, is useful in lots of ways. If I know that rope Q stretches 1.5% at 200lbs of load, 8% at 800 lbs (which happens to be the WLL/10%of Gross tensile and stretches 20% at rupture I can handily calculate whether I'm near my rope's WLL (or am about to overload the line). It also lets me estimate how much actual pressure I'm applying to the tie in point. The fact that it isn't a linear progression doesn't preclude calculating SAFE or UNSAFE degrees of stretch.
MasterBlaster
TreeHouse Elder
I've been glad on several occasions that my climbing rope was dynamic!
I'm on Tom's side here. A rope with less stretch for pulling would be my choice. However if all I could find was a bungie cord then that is what I would use. Make the best of what you have.
I like like having the control and feel you get in a more static line. If you pull the rope two inches you move the tree two inches not just stretched the rope two inches.
I like like having the control and feel you get in a more static line. If you pull the rope two inches you move the tree two inches not just stretched the rope two inches.
Stumper
One Man Band
FWIW, I don't disagree with BigJohn and Tom. I've used both static and semistatic kernmantles(I have not used a full dynamic mountainneering/rockclimbing rope) plus various 3 strands. Each has properties that you can employ to your advantage. My preference when working solo and pretensioning then tieing off continues to be the more dynamic lines. To each their own.:angel:
Stumper
One Man Band
Most of our 12 & 16 strands are more likely to stretch 3-5% at 800lbs of load. Double braids are supposed to stretch much less.(Stable braid is rated for 1.7% stretch at 20% of tensile).
