>2,300 students ... The rope, provided by Pennsylvania Power and Light Co., had been intended for use in heavy construction, and was rated to withstand 13,000 pounds of stress.
What's astounding is that at least in this case simple arithmetic could have shown it was unsuitable - since 13,000 / 2,300 is just 5.6 pounds - a force any below-average middle schooler can obviously exert at least briefly (being well under 10% of their body weight and for reference the weight of less than two stacked 13-inch Macbook Pro notebooks[1] -- which would weigh 6 pounds. A gallon of milk weighs 8.6 pounds.) It could have been expected that perhaps every one of those students would exert it continuously through the whole contest to say nothing of their maximum extra effort on top of it.
While 13,000 pounds is very strong - a full 6.5 tons - it sounds like a simple arithmetic check could have saved the disaster mentioned in the write-up. The lesson - or at least one lesson - is, never feel above a simple calculation.
Technically you'd have to divide the 2300 by two. (1150 students pulling on a rope attached to an immovable wall exerts the same force on the rope as 1150 students pulling in each direction.) Still, even at 11.2lb per student, it's obviously easily attainable.
Edit: also not all the students were competing at once. Still, even with only a few hundred it'd be too close for comfort. For a safety-critical thing like this you want a healthy margin.
This is a great rule. It's most obvious when avoiding slipknots or knotless loops, but people should also be aware that you can get into real trouble with fixed loops - if you fall or are pulled, you don't want to catch your whole weight on a single joint.
Random bit of information cluttering my brain. When playing tug of war, hold the rope with your thumbs pointed towards yourself. A trained professional can usually pull about 0.8-1.0x their body weight that way vs. about .5-.7x with thumbs away. Looped around a waist and the same person can get up to about 1.0-1.5x with cleats on turf. Obviously there is lots of variance for type and thickness of rope as well as footwear and surface but the general principal stands, hold the rope thumbs towards yourself. Source: I studied thrown rope rescues in swift water situations.
I don't think pilom is arguing looping the rope around your hand; he's arguing to zig-zag the rope a bit so that he force pulling on it tried pulling it through your fingers (pinkie first), perpendicular to the direction of the rope, instead of parallel to it, so that it can slide out of your fingers.
I am not sure that works with tug of war ropes, though, as they, given the forces used, are too thick to allow for that zig-zaggy bend.
He was referencing this statement from the GP: "Looped around a waist and the same person can get up to about 1.0-1.5x with cleats on turf." Point is, if tug-of-war players have been known to lose hands because the rope was wrapped around them, do you really want to see what happens when you wrap it around your waist? Maybe it's safer because your body is much thicker than your wrist, but is that really an experiment you want to run?
> do you really want to see what happens when you wrap it around your waist?
The last player on each end can safely wrap the rope around themselves if they like. The rope behind them is slack, so the only tension on the rope is the tension they put on it themselves. Where people get into trouble is when they are somewhere in the middle where there is (significant)tension being applied to their section of rope by people on either side.
A footnote of history, but fraternities were once known for intense competition and a yearly tug of war between houses was common. Part of the history of tug of war I guess?
The fraternities train like hell for months, it's the real deal.
If you want to see one hell of a tug of war look up "NIU tugs" on youtube.
The really old pictures show it was traditional done over stream so the losers get soaked. Now it's done on dry ground but it's still just as serious. The ropes and other equipment we used likely dated back to the 60's or earlier. The rope was so huge...Maybe 5 inches... It was definitely made for boat anchors
What's astounding is that at least in this case simple arithmetic could have shown it was unsuitable - since 13,000 / 2,300 is just 5.6 pounds - a force any below-average middle schooler can obviously exert at least briefly (being well under 10% of their body weight and for reference the weight of less than two stacked 13-inch Macbook Pro notebooks[1] -- which would weigh 6 pounds. A gallon of milk weighs 8.6 pounds.) It could have been expected that perhaps every one of those students would exert it continuously through the whole contest to say nothing of their maximum extra effort on top of it.
While 13,000 pounds is very strong - a full 6.5 tons - it sounds like a simple arithmetic check could have saved the disaster mentioned in the write-up. The lesson - or at least one lesson - is, never feel above a simple calculation.
[1] https://s.blogcdn.com/www.engadget.com/media/2013/10/dsc0890...