The Reef (Square) Knot

To tie the knot move the mouse along the numbers 1 - Reef.
Alternate between Reef and Structure to see the structure.
Compare with Granny and Thief Knots.

First Time: The Reef (Square) Knot (ABOK # 1402, p 258) is usually learned when we tie the Shoelaces on our first pair of shoes. Admittedly it is usually a bow that we tie - but the underlying knot is a Square (Reef) Knot. We also learn just how unsatisfactory the knot is. It slips, it comes undone, it jams, and it is all too easy to tie a granny instead which behaves even less well. Move Your Mouse over the picture on the right to demonstrate how even a "Stack" of reef knots can be capsized and then pulled undone easily. This photograph was created just by pulling on the ends of the blue rope. "There have probably been more lives lost as a result of using a square knot as a bend (to tie two ropes together) than from the failure of any other half dozen knots combined." (ABOK page 258).

Uses: Despite it's faults, the reef (square) knot is quite widely used, e.g., when tying string round a Parcel or joining ropes together. However, its liability to failure should be understood. It should never be used for critical loads or supporting people.

Variations: When the Reef (Square) Knot is used it is common to add additional half hitches as security - a tribute to how unsatisfactory a knot it is. When surgeons tie such knots they commonly use a variation of the Square (Reef) Knot - in the first half knot they take the ends around each other an additional time. This has the advantage of gripping better while the second, third (and more) half hitches are added. They call it a "Surgeon's Knot".

The Reef (Square) knot can also be tied using bights (loops). For example, to use up long shoelaces, the knot can be tied with loops from the start. This means the final "bow" cannot be untied by pulling the ends - but it makes a secure knot.