Convert from sack [UK, wool] to keel [coal]

Unit Definition (sack [UK, wool])
The sack [UK, wool] is a traditional unit of weight, varying for different commodities shipped in sacks. In Britain, for example, the sack was a traditional measure for wool, fixed by Edward III at 364 pounds (26 stone) in 1340.

Unit Definition (keel [coal])
The keel is a traditional British unit of weight for coal. After considerable variation, the keel of coal was standardized in 1695 as 21.2 long tons, or 47 488 pounds (21.5402 metric tons). This is the approximate weight of coal carried at that time by barges on the river Tyne in northern England; the barges were also called keels, from the Dutch word kiel for such a ship.