Convert from shaftment [ancient] to pulgada

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).

Unit Definition (pulgada)
The pulgada is a traditional Spanish inch, equal to 1/12 pie. The pulgada varies from about 23.2 to 24.1 millimeters (0.913 to 0.949 inch).