Fisherman's knot (single)

Each end forms an overhand knot – the simplest knot of all – around the other cord. These overhands can slide back and forth on the other cord. When you pull the two standing parts, they travel towards each other and press together. Neither can get past the other, and so the join holds.

Because the knots are squeezed tightly together under load, they jam. With thin cord this is intended: the join is meant to stay. With thick or very slick rope, however, the plain overhands often lack grip; there the double fisherman's, with two turns per knot, or a double sheet bend is better.

A good fisherman's knot consists of two small overhands tied as mirror images of each other that nestle snugly together, with no gap and nothing sitting crooked. If the knots are not mirror images, they sit crooked against each other and hold less well.

Set each overhand around the other cord individually first, before sliding them together. Then pull on the two standing parts until they sit firmly against each other. The two short tails should stick out clearly; with slick fishing line leave them a bit longer. Do not trim excess tails too short.

The fisherman's knot suits thin cords, string or fishing line that are to stay joined permanently. It is also good for turning a piece of cord into a ring, for example for a pendant, a bracelet or a loop on a knife handle. Because the knots can slide along the cord as long as they are not loaded, you can even make an adjustable loop this way.

It is less suitable for thick or slick rope and anywhere the join must be untied later. After loading it often sits so tight that you can only cut it open. Then the Zeppelin bend or the double sheet bend are better alternatives.

The most common mistakes are overhands that are not tied as mirror images and tails that are too short. In slick cord a short tail can slip back through the overhand under load, and the join comes apart. So check especially with synthetic cord that the tails are long enough.

When knotting fishing line, watch out for sharp hooks and loose scraps of line, which can be dangerous for animals – take your waste with you. The double fisherman's is also used in climbing; this page teaches nothing for that. Life-safety use of knots only after proper training with certified equipment.

The single fisherman's knot is a very old knot used for joining fishing lines and cords. It shows a principle found in many knots: two simple knots that block each other together make a join. Turn the single overhands into double ones and you get the double fisherman's, which is considered the more secure form in many fields.

To practise, take two pieces of cord in different colours. This lets you see exactly where each end goes and spot at once whether the two knots are mirror images.