Square Knot (Bend)
(Also Known As: Reef Knot)

Uses: Used to tie two ends of a single line together such that they will secure something that is unlikely to move much, such as furled sails or a bandage. (The knot lies flat when tied with cloth and has been used for bandages for millennia.) With both ends tucked (slipped) it becomes a good way to tie shoelaces. It is also used decoratively.

Efficiency: 48%

Instructions: 1) Tie a left-handed overhand knot and then a right-handed overhand knot or vice versa. (The Boy Scout instructions for this knot are: right-over-left and under; left-over-right and through.) 2) Pull the knot tight.

Notes: The working ends of the square knot must be cis (that is, both at the top or both at the bottom); the other lines lead to the full rope. This is important; if the line ends are trans (that is, top on one side and bottom on the other), you produce a thief knot, which may slip out under load.

It is also called a reef knot because it was used to "reef" or tie up sails. It is called a square knot from its appearance.

A number of knotting guides have voted this knot "the worst knot", and noted that more deaths and injuries have been caused by its misuse than all other knots combined. Its symmetry and initial feel of security have led to it having a wide and undeserved reputation as a secure knot, which it certainly is not, especially if the ropes are of differing sizes or materials, or if the rope is likely to be bumped.