Break Test on Rope from Danish Peat Bog

[moray]

Break Test on Rope from Danish Peat Bog

Well, it didn't really come from a bog, and it's not Danish, but it's close, as you can see from the first two pictures.

This rope is a piece of 1/2 inch 3-strand hard-laid (at least it is hard, now) polyester rope and is about 35 years old. My friend the local arborist bought it just when the synthetic ropes started replacing manila in the arborist trade in the mid-70's, and he's used it more or less continuously ever since along with two or three others just like it. This man is the poster boy for rope abuse. He drops wood on them, he uses them for light rigging, he drags them through the dirt and mud, they get soaked with rain, they freeze in the winter, they get splashed with tree paint and chainsaw oil, they get nicked by his saw and gored by his spurs, --I could go on. He has never washed a rope in his life.

We don't know the precise history of the piece I tested, only that it surely was abused and heavily used.

 

[ropensaddle]

Break Test on Rope from Danish Peat Bog

Well, it didn't really come from a bog, and it's not Danish, but it's close, as you can see from the first two pictures.

This rope is a piece of 1/2 inch 3-strand hard-laid (at least it is hard, now) polyester rope and is about 35 years old. My friend the local arborist bought it just when the synthetic ropes started replacing manila in the arborist trade in the mid-70's, and he's used it more or less continuously ever since along with two or three others just like it. This man is the poster boy for rope abuse. He drops wood on them, he uses them for light rigging, he drags them through the dirt and mud, they get soaked with rain, they freeze in the winter, they get splashed with tree paint and chainsaw oil, they get nicked by his saw and gored by his spurs, --I could go on. He has never washed a rope in his life.

We don't know the precise history of the piece I tested, only that it surely was abused and heavily used.

He ain't climbing tall trees with that rope lol.

 

[moray]

The bog rope was too short for me to do a knotless bollard-to-bollard pull test, so I chose to tie each end to a clevis pin with a clove hitch, the same hitch I believe my friend actually uses to anchor to his saddle.

The rope broke at one of the hitches at 2754 pounds.

The experiment was poorly performed on my part. I have an anti-recoil snubbing system of my own poor design that is driving me nuts. It snubs the recoil just fine, but it can't be adjusted as the tested rope stretches longer and longer. I have to make a rough guess how long the snubber needs to be, and if the snubber looks like it will lose all slack before the test rope breaks, I have to release tension and give the snubber more slack. During this test, I had to do this 3 times, the last time at near 1900 lbs. tension. My bad. Had I been able to smoothly increase tension without interruption, I suspect the rope would have made it to 3000 lbs. at least.

And of course we are talking about a knot, not native rope strength. If we make the more or less reasonable assumption that the clove hitch preserves 75% of rope strength, then the rope itself has a tensile strength of about 4000 lbs.

We don't know the orginal rated strength of the rope. The most similar rope I know of is Samson TreeMaster with a tensile rating of 7000 lbs. It would seem reasonable to make some allowance for improvements in rope technology since 1975, and grant the original rope a tensile strength of 6000 lbs.

Conclusion: after 35 years of hard use and outright abuse, the rope still has 2/3 of its original strength!

I must say, this is not the outcome I expected. I will continue to wash my ropes and treat them well. However, this experiment does leave me heartened to know how extremely rugged and longlasting our lifelines actually are.

 

[ropensaddle]

The bog rope was too short for me to do a knotless bollard-to-bollard pull test, so I chose to tie each end to a clevis pin with a clove hitch, the same hitch I believe my friend actually uses to anchor to his saddle.

The rope broke at one of the hitches at 2754 pounds.

The experiment was poorly performed on my part. I have an anti-recoil snubbing system of my own poor design that is driving me nuts. It snubs the recoil just fine, but it can't be adjusted as the tested rope stretches longer and longer. I have to make a rough guess how long the snubber needs to be, and if the snubber looks like it will lose all slack before the test rope breaks, I have to release tension and give the snubber more slack. During this test, I had to do this 3 times, the last time at near 1900 lbs. tension. My bad. Had I been able to smoothly increase tension without interruption, I suspect the rope would have made it to 3000 lbs. at least.

And of course we are talking about a knot, not native rope strength. If we make the more or less reasonable assumption that the clove hitch preserves 75% of rope strength, then the rope itself has a tensile strength of about 4000 lbs.

We don't know the orginal rated strength of the rope. The most similar rope I know of is Samson TreeMaster with a tensile rating of 7000 lbs. It would seem reasonable to make some allowance for improvements in rope technology since 1975, and grant the original rope a tensile strength of 6000 lbs.

Conclusion: after 35 years of hard use and outright abuse, the rope still has 2/3 of its original strength!

I must say, this is not the outcome I expected. I will continue to wash my ropes and treat them well. However, this experiment does leave me heartened to know how extremely rugged and longlasting our lifelines actually are.

I used to climb on them old ropes they were tough sobs. Rope construction has a lot to do with durability and stranded ropes are great in this application. I have never cleaned a rope more afraid of that than using one dirty. I had a rope like that I used for ten years and someone stole it but it had many years of pine sap to protect it. The only time my ropes get washed is if it rains and I have to take cover.

 

[Norwayclimber]

I must say, this is not the outcome I expected. I will continue to wash my ropes and treat them well. However, this experiment does leave me heartened to know how extremely rugged and longlasting our lifelines actually are.

Similar results were found by Pit Shubert working for the UIIA (european mountainering council) when testing used rockclimbing ropes, up to 40 years of age. The results are published in a book "Sicherheit in Fels unbd Eis", but to my knowlage its only printed in german.