Naval Action, by Lou Coatney, is a set of free wargames rules for miniatures battles in the World War II Pacific Theatre. The page also provides some markers to use in place of model ships.
naval
1666 Naval Rules For Anglo Dutch Wars
1666 is a set of free wargames rules for naval combat in the Anglo Dutch wars. The game is designed for 1/2400 ships on a 2 inch hex grid. Direct download.
WWII Naval Rules
Gettysburg Gamers offer a set of free wargames rules for WWII navies.
High Seas Drifter WWII Era Battleship Rules
High Seas Drifter is a set of free wargames rules for playing battleship combats in the World War II era.
Steel Ships and Iron Iron Hearts Pre-Dreadnought Rules
Steel Ships and Iron Hearts is a set of free wargames rules for pre-dreadnought naval combat. The rules set dates to 1982 and was played by the Olympic Wargaming league. Classic stuff.