Double Simon (Under)

The Double Simon Under is a bend used to join two ropes together, offering the highest security of the four Simple Simon variants. It is the recommended choice when maximum holding power is required, particularly with very slippery synthetic ropes or when joining ropes of significantly different diameters.

This knot excels in applications where the Sheet Bend or Double Sheet Bend would be unreliable—modern high-performance synthetic cordage, polypropylene, and other low-friction materials that challenge traditional bends.

The Simple Simon bends were invented by Dr. Harry Asher, a retired research scientist and prominent member of the International Guild of Knot Tyers. The Simple Simon Over, Simple Simon Under, and Double Simon Over were published in his 1989 book The Alternative Knot Book. The Double Simon Under follows the same structural logic as the other variants, combining the doubled wrap of the Double Simon with the more secure 'Under' crossing.

Asher described his approach: 'When I had decided that the way to try for new bends was to think of the two halves separately, and then decide how to put them together. There seemed to be no better way than to start with the two halves that make up the famous Sheet Bend... an open loop and a single hitch.'

The Simple Simon family includes four main variants of increasing security: Simple Simon Over, Simple Simon Under, Double Simon Over, and Double Simon Under. Dick Clements later developed the Symmetric Simple Simon (SSS), published in Knotting Matters in 2006.

The Double Simon Under is tied like the Simple Simon Under but with an additional wrap around the bight before the final tuck. Form a bight in one rope, pass the working end of the second rope up through the bight, wrap it around both legs of the bight twice (rather than once), and then pass it back through the bight parallel to where it entered. As the working end crosses back to complete the knot, it passes UNDER its own standing part, creating the characteristic X pattern of the 'Under' variants.

The combination of the doubled wrap and the 'Under' crossing provides maximum friction and security. As with all Simple Simon variants, the two running ends should emerge on the same side of the knot.

The Double Simon Under is the most secure of the four Simple Simon variants. The doubled wrap provides substantial additional friction, and the 'Under' crossing locks the working end against its standing part more effectively than the 'Over' crossing. This combination makes it highly resistant to slippage even in very demanding conditions.

For critical applications with slippery synthetic ropes or significantly mismatched rope diameters, the Double Simon Under is the recommended choice from this family. It provides security comparable to more complex bends while remaining relatively simple to tie and inspect.