A crook, is a natural bend in a tree, used to make knee’s, it’s regarded as the strongest type of natural joint, a natural crook was considered to be stronger than a joint created by bending straight timber using steam.
Shipbuilders would scour the forests around Jervis Bay looking for natural crooks to use in their shipbuilding, commonly taken from the junction of a trunk and a branch, a naturally formed curved branch, or from the large side roots growing off a tree.