Bight (knot)

Sources differ on whether an open loop or U-shaped curve in a rope qualifies as a bight. Ashley (1944) treats bights and loops as distinct, stating that a curve "no narrower than a semicircle" is a bight,[3] while an open loop is a curve "narrower than a bight but with separated ends".[4] However, The Illustrated Encyclopedia of Knots (2002) states: "Any section of line that is bent into a U-shape is a bight."[5]

In order to make a slipped knot (also slipped loop and quick release knot), a bight must be passed, rather than the end. This slipped form of the knot is more easily untied. The traditional bow knot used for tying shoelaces is simply a reef knot with the final overhand knot made with two bights instead of the ends. Similarly, a slippery hitch is a slipped clove hitch.

The phrase in the bight (or on a bight) means a bight of line is itself being used to make a knot. Specifically this means that the knot can be formed without access to the ends of the rope.[6] This can be an important property for knots to be used in situations where the ends of the rope are inaccessible, such as forming a fixed loop in the middle of a long climbing rope.

Many knots normally tied with an end also have a form which is tied in the bight (for example, the bowline and the bowline on a bight). In other cases, a knot being tied in the bight is a matter of the method of tying rather than a difference in the completed form of the knot. For example, the clove hitch can be made "in the bight" if it is being slipped over the end of a post but not if being cast onto a closed ring, which requires access to an end of the rope. Other knots, such as the overhand knot, cannot be tied in the bight without changing their final form.

• Ashley, Clifford W. (1944). The Ashley Book of Knots. New York: Doubleday. ISBN 9780385040259.
• Budworth, Geoffrey (2002). The Illustrated Encyclopedia of Knots. ISBN 9781585746262.