Away Boarders is a neat little game for a little-considered theatre of war: The Great Lakes in the late 18th and early 19th centuries. The author also includes some nice 2-D paper models of the ships, as well as counters.
Rules: Naval
Empires of the Seas Age of Sail Rules
Empires of the Seas is a set of rules for the Age of Fighting Sail. The author says that the rules allow battles between large fleets without lots of record keeping.
Firepower Naval Rules
Firepower is a set of free wargames rules for naval battles. The rules cover the period 1900 – 1945.
A Hotter Fire ACW Naval Rules
A Hotter Fire is a set of free wargames rules for naval combat between civil war ironclads.
Away With Honour – Middle Ages Naval Warfare
Away with Honour is a set of free wargames rules for naval warfare in the Middle Ages by Tony Cullen.