Cotton seine twine will rot if not put away correctly. Tarring and salting preserved it, but so did winding it on reels so the air could blow through. Either approach meant lots of handling. Synthetic fibers like nylon and polypropylene, available and affordable after the war, brought the salting, tarring, and airing to a welcome end.
Alert and most of the other moored vessels look to be set up for seining herring or mackerel.