Here are a set of WWII Naval rules created by the author for playing with his homemade WWII ships.
Rules: Naval
Steam Iron and Tin ACW Naval Rules
Steam Iron and Tin is a set of 15mm ACW naval rules that was distributed to people who attended the 1985 Origins Convention in Baltimore (I was at that convention!).
De Bellis Navalibis
De Bellis Navalibis is a set of free wargames rules for playing ancients naval wargames.
Iron and Steam Rules
Iron and Steam is a set of free wargames rules for pre-dreadnought Victorian naval actions.
Iron and Steam is a set of miniatures rules for naval combat of the American Civil War. The rules feature a gun-by-gun combat resolution, written orders and simultaneous movement. Traditionally played with 1/600 scale models the combat scale is closer to 1/2400 scale, though the game is generally model scale agnostic. Also included are over 100 pre-filled ship record sheets, turning radii and arc-of-fire templates as well as a 2 page QRS to facilitate fire resolution.
ACW Rules For River and Coastal Warfare
By Jeff Peach & Les Booth offer a set of free wargames rules for ACW River and Coastal Warfare