Convert from mark twain to wah [Thailand]

Unit Definition (mark twain)
The mark twain or twain is an old word for the number two, derived from the Anglo-Saxon twegen. The American author Samuel Clemens (1835-1910), who had been a riverboat pilot on the Mississippi in his youth, took his literary name from a traditional riverboat phrase "mark twain", meaning "exactly two" fathoms of water. This was the minimum depth needed for the boats to operate safely without running aground.

Unit Definition (wah [Thailand])
The wah is a traditional unit of distance in Thailand, now aligned with the metric system as exactly 2 meters (6.562 feet). This unit is the Thai version of the fathom. It is seen mostly in connection with the talangwah or square wah (4 square meters or 4.784 square yards), a common unit of area in Thailand.