This looked like a fun game to try with my youth group, but I need to have the solution before I do it. It involves untying an overhand knot in the middle of a rope by placing one’ hands on either side of the knot and not letting go of the rope.
My thought process involved opening up the knot to a big loop (sliding hands along the rope without letting go), passing it over my body, and, voila, the knot would be untied. However, when I tried it with a real rope, I discovered it doesn’t work. Topologically, having one’s hands on either side of the knot is equivalent to having a loop of rope with no free ends and a knot in the middle. I don’t see any way to untie that configuration.
The only solution I can see would be manipulating the end of the rope through the loop with one’s fingers and passing it to the other side, but this is a broader interpretation of “not letting go” of the rope.
When you grab the ends of the rope, you form a closed loop consisting of the rope and you. You can’t remove the knot from this loop without breaking it, but you can move the knot from one part of the loop to another. So, basically, what you need to do is transfer the knot to your arms, at which point the rope part of the loop will be unknotted. The knot’s still there (in your arms) at the moment you let go, but nobody will notice that.
Youth group + “Be aware that the players may end up in close physical contact with each other during the game” = Why I actually went to any of those dumb things as a teenager.
The standard trick goes the other way. i.e. Pick up a rope section & tie an overhand knot without letting go. The technique is to cross your arms, then pick up the rope ends, then uncross your arms, pulling the ends past each other into an overhand knot as you go.
Doing that in reverse ought to get your result. You’ll first need to open up the overhand loop big enough to run your crossed arms through to grasp the opposite rope ends.