Convert from yard to shaftment [ancient]

Unit Definition (yard)
The yard is a fundamental unit of length in both the U.S. Customary System and the British Imperial System. Originally taken to be the average length of a stride, the yard is actually equal to 3 feet; defined as 91.44 centimeters.

Unit Definition (shaftment [ancient])
A shaftment, when used as a unit of length, is usually six inches or two palms, i.e. 15.24 cm (for the international inch). It is thought to be the distance from the tip of the outstretched thumb to the other side of the palm.In English this unit has mostly fallen out of use, as do others based on the human arm: digit (1/8 shaftment), finger (7/48 shaftment), palm (½ shaftment) hand (2/3 shaftment), span (1½ shaftments), cubit (3 shaftments) and ell (7½ shaftments).