Ropes become lines the moment they enter the vicinity of a boat (unless you are the select few ropes that remain a “rope on a boat”). The trouble is, these sheets, halyards, jacklines, and other control lines all get dirty over time. Between the salt that gets into the fibers and the algae that grows on them if they don’t dry out enough, the lines become filthy!
When you remove a line from a boat and turn it back into (dirty) rope, you may want to clean it. Washing machines are not a good idea as all the agitation will form infinite knots in your ropes. Many detergents (especially fabric softeners) will actually weaken the strength of the rope. You are pretty much left with the option of a bucket filled with Dawn Soap and water.
You could simply mix the rope around in the bucket for a while and try to work the dirt out of the rope fibers the best you can, but this will end up with a dirty rope where the only thing that came out in the wash were the good intentions.
The next option is to add a brush to the equation. A good scrub brush will help loosen and remove dirt and other contaminates from the rope and its fibers, but scrubbing a rope can be rather challenging.
A friend of mine made this apparatus to facilitate the cleaning process of his jib sheets. The brushes are simply clamped to a sturdy table, allowing him to work the rope through the brushes with both hands to really clean them up well. The rope that is waiting simply soaks in the soapy water of the bucket, helping to loosen any filth that is on the line.
As the rope gets cleaner, the water can be changed out to prevent the clean rope from stewing in the old filthy water. The process really makes an impossible task much easier, and the end result is a much cleaner jib sheet once it is returned to it's home on the boat.