Some have been surprised not to find how to use a clew on the Internet.
They would not find much on wassit either. Wassit was the inexpensive, tightly spun, indigo dyed, knitting yarn that was ubiquitous on the shores of the English Channel 500 years ago. It was used for knitting everything from underwear and socks to ganseys for the fishermen. Why doesn’t something that important show up on the Internet?
A clew is simply a hook, hung from the belt, on which a ball of yarn is impaled. Many designs work. I simply bent a spiral of wire so that it clipped on to a leather work belt and held a wire claw (from the same root) upwards to hold my yarn.
Very likely some of the hooks on the lower end of knitting sheaths, that museum curators tell me were to hold the knitting, were actually clews to hold yarn. (Since the museums did not have needles for those sheaths, it is unlikely that the curators had actually tried knitting with such an arrangement.) However, as you knit round and round, hooks attached to the knitting get all tangled up. However, used as clews, the hooks hanging from the bottom of the knitting sheath work just fine. And, even when I am working on the second sleeve, I have not had a problem with the gansey touching the floor. So, I see no need or advantage from a hook to hold the knitting.
Clews work with either center-pull or outside in balls. Every so often you will have to reset the ball, and for center pull balls, rewind them, but it is knitting, not rocket science. They are useful if you are camping or knitting while walking or if your hut has a mud floor.