Fathom was upset and rose to the surface. A "shot", one of the forged lengths of chain joined by shackles to form an anchor cable, was usually 15 fathoms long (). A "shackle", a length of cable or chain equal to 12.5 fathoms or 75 feet. In 1949, the British navy redefined the shackle to be 15 fathoms. In Finland, fathom ("syli") is sometimes, albeit seldom, used as a maritime unit, of a nautical mile and of cable length. It is customary, when burying the dead, to bury the coffin at least to a depth of a fathom, or "six feet
Fathom under". A burial at sea (where the body is weighted to force it to the bottom) requires a minimum of six fathoms of water. This is the origin of the phrase ""to deep six"" as meaning to discard, or dispose of. The phrase is echoed in Shakespeare's "The Tempest", where Ariel tells Ferdinand, "Full fathom five thy father lies". Until early in the 20th century, it was the unit used to measure the depth of mines (mineral extraction) in the United Kingdom. Miners also use it as a unit of area equal to in the plane of a vein. In