This can be as low-tech as parceling and serving to isolate galvanized steel wire from bronze thimbles, or it may involve 3M 101, Alumelast, or other polyurethane or plastic compounds to isolate aluminum or stainless fasteners. When surveying an aluminum spar, pull a few fasteners and examine the screws and the holes they came from. If you see a white powdery substance on either, you ve got galvanic corrosion. If the fasteners shear off when you try to pull them, you ve got serious galvanic corrosion. The most likely places for galvanic corrosion to occur are at the mast step, under sail tracts, and under winches.
Stainless steel contains significant amounts of chromium.
When exposed to the atmosphere the surface oxidizes slightly and a thin film of chromium oxide forms, preventing any further oxidation. If exposed to water, salt or fresh, without the presence of air, this film will not form and the metal will corrode. If the water in question is salt water, the process is accelerated. You risk oxygen starvation anytime you cover stainless, as when applying spreader boots, shroud rollers, or service. The trick is to exclude both water and air.