In 2012, the French National Mountain Guide School (ENSA) began to research how knots in climbing ropes decrease the impact of a fall on a climber. Guides have been testing this for years in unscientific ways and have always come up with the same result. Mostly it works.
The difference between a guide does in a training and what ENSA did is that ENSA took a scientific approach to the question. They used a load cell to measure the force…and what they found wasn’t terribly surprising. Knots do help…
Check out the following video for more:
In review, they found that bulky knots are better. They recommend that you use a figure-eight on a bight rethreaded through itself. Most American guides have been using butterfly knots, but this video may have a long term impact on that methodology.
They found that in icy conditions, knots don’t help that much.
And they recommended the following distances for rope between knots:
