Steffy: A timber, or assembly of timers, that could be rotated about an axis to control the direction of a vessel underway. Until the middle of the medieval period, the practice was to mount rudders on one or both stern quarters; these were known as quarter rudders. By the late medieval period, however, it appears that most vessels of appreciable size were steered by a single rudder hung at the sternpost; these were known as stern-hung rudders. For a brief period, the two types were sometimes used in combination. Rudders were designed for the vessel and type of duty they served. In protected waters they could be made quite broad, while seagoing ships utilized longer, more narrow rudders. For the largest seagoing ships, rudder construction was complex and required huge timbers, the assembly sometimes weighing several tons.