The video systematically tests and clearly demonstrates the effect of brake knots in the event of a crevasse fall:
Brake knots are very effective when there is enough snow (>1m). With little snow on bare ice, the brake knots have virtually no effect as they cannot dig deep enough into the snow.
Three knots are sufficient to significantly reduce the force acting on the person holding the fall.
Braking knots should be relatively large and use as little rope as possible. At the end of the video, the knot recommended by ENSA is explained (a modified figure of eight). It is also recommended: one knot at a distance of 3m from each person, then two more at a distance of 2 meters from the first knot.
Braking knots are particularly important for two rope teams, as it is of course all the more difficult to hold a fall alone.
In addition: YouTube videos are great and interesting, but of course they are no substitute for "offline" courses. Your trusted guide is sure to know a good column for practicing!
