One-Way Knot
This knot ties two ropes together in such a way that they will pass through a pulley in one direction.
Start with a figure-8 in one end of one rope
The finished knot.
This knot will only pass through a pulley in one direction because of the short tails
which come out of the same side. FYI you will still need a knot passing pulley to
make this work, and this knot is not as strong as a barrell knot