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Looking at the graphics and knowing the answers, and having limited experience tying knots in serious situations, I still don't intuit why one knot is more secu
by mmooss 2y ago
Looking at the graphics and knowing the answers, and having limited experience tying knots in serious situations, I still don't intuit why one knot is more secure than another. I have no idea of the principles:
* Increased friction, I assume, is the fundamental difference. Is that correct? That still leaves the question of what, in practice, contributes to friction significantly, what is inconsequential, what works or fails in combination, etc.
* How much friction do different knot components have? Can we determine the strength of a knot by simply adding the friction in different components?
* What effect does compression of the cordage have?
* How much does effect does the cordage material's natural friction have?
* What does failure really depend on, in practice? Powerful traction forces? Lubrication? Back and forth movement (e.g., that loosens the knot)?
* Can 'give' make a significant difference, in either the knot's form or in the material? As in all solid things, a knot with more give should apply less force to failing parts.
* Is distribution of forces important? A knot that distributes powerful forces to multiple spots should perform better, theoretically.
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- bubblyworld 2y agoI don't have any answers for you but as an avid climber - you also want to be taking into account the material you are tying knots in. Super static material like dyneema really doesn't like being bent at a tight angle and will lose a lot more strength in a knot than something like nylon. Also thicker material tends to lose less strength (bigger bend radius). But yeah... beyond that my usual method of understanding a knot is to find the places where one part of the knot constricts another under load, because that generates the friction. For instance the reef knot in the linked article has two collars that bite on two strands of the rope each when pulled, so lots of friction there and it makes sense to me it's very syrong. On the other hand I can't work out how the granny knot is stronger than the thief! Very subtle stuff.
- deleted 2y ago[deleted]
- blacksmith_tb 2y agoNumber of crossings tends to help (by spreading the friction around, though still not evenly). And I think people don't tend to consider just how much having any knot will weaken a rope - the basic overhand more than halves the strength[1]. 1: https://igkt-solent.co.uk/knot-strength-chart/ https://igkt-solent.co.uk/knot-strength-chart/
- mmooss 2y agoIn answer to my own question, I found this: https://news.ycombinator.com/item?id=42523884 https://news.ycombinator.com/item?id=42523884