STOP USING A KNOT FOR YOU BACKUP LINE
Why we should definitely start using Linelocks as standard for our backup on Highlines
28/12/2023
KNOT vs LINELOCK for your highline backup
It has not only been discussed one time but many times - is it actually safe enough to use a knot to attach the principal backup webbing of our highline set-up to the anchor?
We have done the backup fall demo (human slackliner) and different “wood” dropping tests, in order to achieve a variety of results that can reflect which option is truly the safest because it is generally more reliable. All tests have been established by our developer and engineer Florent, who has come to a conclusion that he urges to share with the community.
FLORENT BERTHET - developer and engineer at Slack Inov' :
“Even if we know that generally knots are quite strong in a “static” pull situation (progressive and slow pulling effort), the same knot can be really weak in dynamically charged situations (shockload). For example, a knot holding usually 65% of its indicated MBS during a static pull, frequently breaks at around only 30% of the original MBS.
Sometimes even lower due to the shockload, like it would or does occur on a backupfall. What happens physically is that a knot is getting super tight when you pull on it.
If you pull smoothly and slowly, the reaction is steady and its progressively tightening until it reaches its maximum and at this point it retains the tension.
If you pull fast (dynamic), then the friction of tightening the knot is creating heat and the fibres melt way before reaching the tensioning point they are used to resisting in a static situation.
Our tests and videos are not a 100% re-creation of our reality in a backup fall, but I tried within our capacities, to get as close as possible to a comparable demonstration of what assures a higher safety - a knot or a linelock for your backup connection?
Our test results show to us clearly, a linelock diminishes the risk by A LOT, and in my opinion an absolute worth one.
I personally recommend to all highliners to stop using knots, as there is additional room for error, and to standardise a rigg with a linelock, in order to reduce to a maximum all potential risk in case of a backup fall situation.
It is safer, stronger and especially way more user-friendly, as it is easier to verify. A knot will always be the more fragile choice and definitely shouldn't be your 1st one.
What's a backup installed worth, if it may not back you up?
I’m aware that backupfalls have already occurred onto knotted backups and (thankfully) the knots held well; however, according to my tests I can declare that we were really close to a dramatic outcome.”
Florent B.
In any case of questions around his tests and results or to reassure yourself of your own rigging habits, feel free to send us a message to get in touch with Florent directly.
[email protected]
