A chain sinnet (or chain sennit) is a method of shortening a rope or other cable while in use or for storage.

It is formed by making a series of simple crochet-like stitches in the line.

To tie: To restore the rope to its original length, pull the end passed in the last step back through the final loop and pull on the free end.

All one needs to do is keep hold of one end and feed throughout of the pile of rope to the other end, then start from the two conjoined ends, or then keep hold of the two ends, and feed back to the middle and then start chaining.

This can be done in confined spaces or dangling in mid-air if need be, and is a common way to manage caving ropes without introducing troublesome twist.