My club has a rope washer made by somebody years ago - don't know who but they made a brilliant job.
Its mounted on the wall in the changing room at the club hut and is a metal framework with two pairs of scrubbing brushes mounted vertically one above the other. There is a copper pipe also monted vertically with holes drilled in which sprays water at the rope from behind as it is pulled through the brushes. At the top are two small jockey wheels through which the rope passes, one being movable but held in place by a weight hing on an arm attached to the wheel axle.