Convert from shaftment [ancient] to step

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 (step)
The step is a traditional unit of distance, equal to 1/2 pace. The step is traditionally equal to 30 inches or 76.2 centimeters. However, U.S. marching bands often use a shorter step of 22.5 inches (57.15 centimeters), so that 8 steps are made every 5 yards; this works well on American football fields, which have a chalkline every 5 yards. Using this shorter step is called marching "8 by 5."