Convert from shaftment to cable [British]

Unit Definition (shaftment)
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 (cable [British])
The cable is a unit of distance formerly used at sea. The traditional U.S. cable was equal to 120 fathoms, 720 feet, 0.1185 nautical mile, or about 219.4 meters. The British Admiralty, in 1830, defined the cable to equal exactly 0.1 nautical (Admiralty) mile, which is 608 feet or about 185.3 meters. The cable is also sometimes now defined as a metric cable, which is equal to exactly 200 meters.