First, don't feel stupid. This board is designed to help people with questions, no matter what the author thinks of his/her project.
Second, in order for something to rust, it needs air. Oxidation (the technical tern fro rust) is the same chemical process as burning something. Fire needs oxygen. It may begin rusting underwater because water naturally has oxygen in it (that's how fish survive), but it will rust water in air. The water provides the other element necessary for rust, surplus protons.
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