Bowline on a bight
|Bowline on a Bight|
|Typical use||Making a loop in the middle of a length of rope.|
The Bowline on a bight is a knot which makes a pair of fixed-size loops in the middle of a rope. Its advantages are that its loops do not slip and it is reasonably easy to untie after being exposed to a strain.
This knot can be used to provide a toe hold in the middle of a rope; to make an emergency bosun's chair; and to create an upper rope "block" to make a crude purchase by threading the rope round an anchor point and then back up through the loop. It is sometimes used in sport climbing to tie into two anchor bolts independently. This knot is convenient when a dependable loop is required but neither end of the line is available. It's also commonly used as a seat while being hoisted as there are two secure loops as opposed to the traditional one loop bowline. In theory, this knot would make hoisting many people with one line possible. This knot is very popular in potholing as it allows the load to be spread between two anchor points, reducing the stress placed on them and providing a backup should one fail. Commonly known as the Y-hang it allows for a free-hang descent and can be easily adjusted to avoid waterfalls or rub points.
The bight of rope is initially used to make a bowline in the usual way (picture on left). However, the bowline is NOT completed by going on round the standing end(s) and tucking the bight back down beside itself. Instead, the bight is opened up to allow the whole knot to pass through it (see picture on right). When tightened, the bight now embraces the pair of standing ends (see top picture)