Winding hole
A winding hole is a widened area of a canal, used for turning a canal boat such as a narrowboat. In sea ports an area for turning ships is usually called a turning basin.
Etymology
The word is commonly believed to derive from the practice of using the wind to assist with the turn.Another etymology, however, is the Old English word for turn - "windan" ). Much UK canal terminology comes from spoken rather than written tradition and from bargees who did not read or write.
It is also possible that the word has a similar derivation to that of the windlass, which derives from the Old Norse "vinda" and "ás"—words currently used in Iceland—where the modern word for "windlass" is "vinda".