From the 15th to the early 18th century, the tiller was controlled by a vertical side-to-side lever attached to its end. The earliest forerunner of the wheel was a horizontal winch drum. The full-fledged wheel made its debut around 1714-15. The wheel pedestal, a late 19th century innovation, contained mechanical steering linkage, and often doubled as a binnacle stand.
Dimension is diameter of the rim excluding handles. Note: Because of machining tolerances, wooden wheels may be slightly "fatter" than metal wheels.