Simple Simon (Under)

The Simple Simon Under is a bend used to join two ropes together, particularly effective with modern synthetic cordage and ropes of different diameters. It is more secure than both the standard Sheet Bend and the Simple Simon Over, making it a reliable choice when working with slippery materials.

The knot is well suited for joining ropes of quite different thicknesses—the bight is formed in the thicker rope, and the thinner rope does the wrapping. The Simple Simon Under holds well even under these mismatched conditions where lesser bends might slip.

The Simple Simon bends were invented by Dr. Harry Asher, a retired research scientist and prominent member of the International Guild of Knot Tyers. They were published in his 1989 book The Alternative Knot Book. Asher developed the Simple Simon knots as an improvement on the Sheet Bend, seeking a bend that would be more secure with slippery synthetic ropes while remaining simple to tie.

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 Simple Simon Under begins like a Sheet Bend: form a bight in one rope, then pass the working end of the second rope up through the bight, around both legs of the bight, and back through the bight parallel to where it entered. The key distinction from the Simple Simon Over is that as the working end crosses back to complete the knot, it passes UNDER its own standing part—hence the name 'Under.' This creates an X pattern where the working end crosses beneath the standing part.

As with the Sheet Bend, the two running ends should emerge on the same side of the knot for proper function.

The Simple Simon Under is more secure than both the Sheet Bend and the Simple Simon Over. The 'Under' configuration creates additional friction by locking the working end against its own standing part, which resists slippage more effectively than the 'Over' version.

Knot expert Geoffrey Budworth notes in The Ultimate Encyclopedia of Knots & Ropework that the Simple Simon Under holds well even with different sized ropes or slippery synthetic ropes. For maximum security, particularly with very slippery cordage or critical applications, the Double Simon Under provides even greater holding power.