Bowline on a bight advocate the use of a figure eight twisted version of the Bowline on a bight. 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
Bowline on a bight a climbing harness by tying a regular bowline knot and then re-threading it, such as is done with a figure eight knot. However, it is "critical" to use a strong backup knot with plenty of tail beyond the knot, as the knot may untie during long climbs. The advantage of using this knot instead of the figure eight knot is that it can be easily untied after a severe fall. The bight of rope is initially used to make a bowline in the usual way (picture on right). However, the bowline is "not" completed by going on round the standing