This link will take you to marine steam. Make up a 10 gallon pot of coffee and lots of snacks. Lavishly illustrated with good pics. Steamboat Press - Specializes in publications about the men, women, and boats to whom the rivers of America were homes and livelihood. The Historical Resources page is excellent for those wishing to do research.
Entire site is a font of information.
Although devoted to locomotive whistles, there is excellent information on construction, theory, links, and a classifieds.