|Names||Reef knot, Square knot (from its appearance)|
|Related||Thief knot, granny knot, grief knot|
|Typical use||Joining two ends of a single line to bind around an object.|
|Caveat||Not secure as a bend. Spills easily if one of the free ends is pulled outward. Does not hold well if the two lines are not the same thickness.|
The reef knot or square knot is a common and simple binding knot.
Tying a reef knot
To tie a reef knot, tie a left-handed overhand knot and then a right-handed overhand knot or vice versa. (Two consecutive overhands of the same handedness will make a granny knot.) A common mnemonic for this procedure is "right over left, left over right".
The working ends of the reef knot must be cis (that is, both at the top or both at the bottom); the other lines lead to the full rope. Otherwise, a thief knot results. (The "cis" and "trans" terms are derived from terminology used to describe geometric isomerism.)
Used to tie two ends of a single line together such that they will secure something that is unlikely to move much. It 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, whilst the non-slipped version is useful for shoelaces that are excessively short. It is also used decoratively and to tie the Obi (or belt) of a Karate Gi. Finally, it is quite handy for tying plastic garbage or trash bags, as the knot forms a handle when tied in two twisted "ears".
This knot's name originates from its use to "reef" (furl) sails, where its easy-spilling behavior was very handy. A sailor could collapse it with a pull of one hand; the sail's weight would make the collapsed knot come apart.
The reef knot is one of the key knots of macrame textiles.
The reef knot's ease of tying and visually appealing symmetry belie its weakness. It is popular as a general-purpose binding knot. In particular, it figures prominently in Scouting worldwide: each Scout is said to know the square knot, and it is pictured in the international membership badge.
The International Guild of Knot Tyers warns that this knot should never be used to bend two ropes together. Some knotting guides claim that misused reef knots cause more deaths and injuries than all other knots combined.
The sheet bend, and in some cases the fisherman's knot, are simple binding knots that can replace the reef knot. Additionally, the zeppelin bend works very well, though it is somewhat more difficult to tie.
- Ashley's Book of Knots ISBN 0-385-04025-3