How strong is your favorite knot? MIT Scientists Invent New Rope Fibers To Study Knots

Previous to this study, many believed that it was the friction between two ropes bent together that prevented slip, but this new research discovered the key feature of a great knot is twist within the core. Twist is also a reason why some knots capsize and fall apart.

They also found that a knot can be made stronger if it has more “circulations,” which they define as a region in a knot where two parallel strands loop against each other in opposite directions, like a circular flow.

By taking into account these simple counting rules, the team was able to explain why a reef knot, for instance, is stronger than a granny knot. While the two are almost identical, the reef knot has a higher number of twist fluctuations, making it a more stable configuration.

I hope they didn’t spend a lot of money figuring that out.

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Glad someone figured out how to figure that out. I was once asked by an AB if there was a way to calculate how many turns around a bollard were enough to hold it to the breaking point. Having nothing better to do I started calculating; but lots of “ifs” material, wet? dry? kinetics? temperature? etc… After hours of off and on research and calculations over days I came up with 4 for his scenario but no guarantee so I told him to go ask the bosun. MIT seems to have simplified things.

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I don’t mean to denigrate what they’ve done – it’s quite fascinating. The initial video talks about using a Nitinol (Nickel-Titanium-Naval Ordnance Lab) wire. It’s fascinating stuff, but it doesn’t change color. They talk more about the stress-sensitive fiber (unspecified composition) in other links from the article.

Why? Just because in this instance we know which is stronger doesn’t mean we understand why it’s stronger.

Well – it seems pretty obvious that in a granny knot only one side is doing the work and the other is mostly trying to upset the knot, whereas in a proper reef knot all the forces are in opposition.

But I shouldn’t talk – I’m the guy who started sailing when I was five and still managed to go through most of a six-year Navy enlistment without realizing that the neckerchief (which, granted, I seldom wore) was tied in a square knot.

Rick Spilman at Old Salt Blog has a post about this, Spliman’s blog is excellent.

This was interesting:

a recent paper by a team lead Vishal P. Patil

“It seems like humans just lucked out and discovered some good knots,” says Patil, “but it’s kind of unclear how.”

He notes that inventing knots seems to be a uniquely human activity and that such complicated knots don’t appear in nature.

“The question of how did people even come up with these knots kind of baffles me,” says Patil. “I guess if you spend a long time at sea, maybe eventually you work out a good way of tying something to something else.”

Rick notes:

As insightful as the new work may be, it is also clear that scientists and sailors occupy different realms.

Marlinspike seamanship is both an art and a science. Over a few thousand years of seafaring, it seems perfectly reasonable that sailors might determine which knots work for specific applications and which do not. Sailors did not need computers or special fibers to develop these knots. Why that should baffle anyone remains unclear, at least to me.

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