There's a lot of great info in this thread. Thanks guys!
Help with rope choice ?
- Thread starter bevis
- Start date
Help Support Arborist Forum:
Oldtoolsnewproblems
ArboristSite Operative
https://www.yachtingmonthly.com/sailing-skills/strongest-sailing-knot-30247So this is based on independent tests, and annoyingly they didn't verify mfrs claim on rope strength, but they saw a 35% reduction with a bowline. I'm on my phone and having trouble navigating the site and I can't find the summary haha but I wonder how the 8 did. Probably better but I don't know by how much.
Specifics aren't the important thing here, at least in my opinion. The take away is really any rope you buy is half as strong as the mfr says when you actually use it in the real world, because no matter what you do there will probably be a knot in it somewhere. And if your trying to be safe, might as well start at 50%, because you still haven't even figured in shock loading etc.
Just food for thought.
Specifics aren't the important thing here, at least in my opinion. The take away is really any rope you buy is half as strong as the mfr says when you actually use it in the real world, because no matter what you do there will probably be a knot in it somewhere. And if your trying to be safe, might as well start at 50%, because you still haven't even figured in shock loading etc.
Just food for thought.
Agree, nobody should be trying to load a 20k lb MBS rope to 20k or even 15k pounds.
35% of max was on dyneema rope...which is not something that's going to be used in pulling trees over. The double braid rope is a much better fascimile.
In their testing the Bowline broke at 47% of max and the figure 8 broke at 53% of max. So, approx 6% difference like I said before. You're right I don't see where they attempted to recreate the MBS testing the manufacturer uses with their system and see if their calibration was correct. So, saying that a rope breaks at 50% when you don't test the 100% is a pointless number. Those percentages can only be useful in relation to each other, not to the MBS designated by the rope's manufacturer.
I also don't see how many of each knot they tested. Did they only use one of each? If so, the numbers are worthless. If they did do multiple tests per knot/rope combo what type of math did they use to get to the percentage they decided to publish?
Would have been nice to know how they terminated the dead ends. I was very disappointed in how the dyneema de gloved and pulled the core out. Very interesting article non the less.
Oldtoolsnewproblems
ArboristSite Operative
Exactly, it's just important for people to really take to heart the notion that you should never be picking up 10klbs with a 12klb rated system and feel plenty safe. Shock loads and terminations eat into your margins fast, so always round up, and try to buy the nicest you can afford when injury is so easy
