Corrosion and corrosion control of trawl wire rope

Graduation date: 1981Trawl cables are wire ropes which corrode under the influence of\ud seawater depending on fishing habits.\ud Information about the problem was obtained from the preceeding\ud work by Robert D. Malloch, and from contacts with the fishermen.\ud Statistical data about fishing boats and fishing habits on the Pacific\ud Northwest Coast are drawn from the answers to a questionnaire sent to\ud the fishermen in September, 1979. Trawl line corrosion is studied\ud with at-dock tests on wire rope, and laboratory tests on single wire.\ud A model of corrosion of galvanized trawl wire rope is derived\ud from cathodic protection calculations and experimental results. This\ud model describes the corrosion due to the influence of bare steel\ud trawl docrs and uniform corrosion.\ud The time needed to corrode the zinc coating is a function of the\ud distance from bare steel trawl doors. Besides the physical constants\ud of the wire rope and of the seawater, the most important parameter\ud is the average electric conductance of the coating on the wire rope,\ud this coating being either an oxide film or an organic coating. Practical methods of protection from corrosion of trawl wire\ud rope are drawn from this study. They are simple enough to be applied\ud by the fishermen themselves