Convert from braza [Spain] to shackle

Unit Definition (braza [Spain])
The Braza is a traditional unit of distance in Spain and Latin America. In Spain it equals 2 varas, 8 palmos, or about 1.67 meters (5.48 feet or 65.75 inches). In Latin America the Braza tends to be larger. The Argentine Braza is 1.73 meters (5.68 feet or 68.16 inches), and under the Texas definition of the Vara the Braza would be 1.693 meters (5.556 feet or 66.67 inches). The Portuguese Braça is similar, but it equals 10 palmos or about 2.20 meters (7.22 feet or 86.6 inches).

Unit Definition (shackle)
The shackle is a traditional unit of length used for measuring the lengths of nautical cables and chains, especially anchor chains. Anchor chains are formed by using shackles to join short lengths of chain. When the anchor is dropped and the chain runs out, a seaman counting the number of shackles can report the total length of chain deployed. The size of the unit therefore varied somewhat, depending on the length of the short chains used. In Britain, the unit became standardized in the 16th century at 12.5 fathoms (75 feet or 22.86 meters). In 1949, the Royal Navy adopted a length of 15 fathoms, which is 90 feet or 27.432 meters; this brought the British shackle in line with the U.S. unit, which is usually called the shot.