Got the big boat out of storage last week. While cleaning, I noticed that both stainless housing for the nav lights have white powdery corrosion. What is a good product to remove the corrosion off stainless and what to stop it and protect the housings. The boat was covered and in a tobacco barn all winter. What causes stainless to corrode? The corrosion is not a spot. it is in stripes about 3" long. Off topic - We used Marine 31 Mildew Guard last year after cleaning with Marine 31 Mildew Remover. We had been fighting the mildew since we had bought the boat. Uncovered on Thursday and no mildew anywhere on the boat. The stuff works.