Any rope that is not wire is fiber rope.  Except in a few instances where it is put to certain special uses, fiber rope is never called anything but line aboard ship.  For example, there are fiber manropes on gangways; foot ropes on hammocks (and formerly on the yards of sailing ships); bolt ropes on sails and other canvas; ridge ropes on awnings but they are usually of wire); dip ropes for passing some object under, outside of, or around another; and bull ropes for heavy heaving without benefit of a purchase (tackle). Some small craft have fiber wheel ropes running from wheel to rudder, although these, again, are more likely to be of wire.  There are other exceptions as well, but all the exceptions merely go to prove the strict general rule that aboard ship a line is never called a rope. In the manufacture of line, the fibers of various plants are twisted together in one direction to form yarns; the yarns are twisted together in the opposite direction to form strands; then the strands are twisted together in the opposite direction to form the line.  In the days when ships swung to fiber anchor cables, three or four lines were twisted together, again in the opposite direction, to form the cable.
