Ram or Die is a set of free wargames rules (and paper figures!) for refighting the Battle of Salamis.
Seas of Lead is a set of free wargames rules for World War II Naval games. Along with the rules are some good looking unit data cards that they made using the Magic Set Editor.
Destroyer Commander is a variant for Mongoose Games’ Victory At Sea that focuses on smaller ship actions. I have always wanted to do Destroyer and PT Boat games.
There are no actual instructions here, but The Penny Whistle has some really neat photos of index card ship models. They should be relatively easy to replicate and look like they could be used in a fun game.
To Glory We Steer is a well-done set of rules for the age of fighting sail:
From the period where the mighty multi-oared Galleys had almost faded from memory other than a coastal raider, to the days where black funnelled Ships of the line belched out sparks and smoke, there existed two hundred years of an Age of Sail. …
This set of rules takes from many contemporary accounts of battle, to gain a whiff of the sea air in themechanics, Hopefully threading through it enough realism without baffling a Landsman who knows little of the Age of Sail.
As you give your crew orders to “Man the Halyards” or unleash a perfectly timed broadside, I hope that some of this may come across and that those who know their foretops from their gaff sails might gain some pleasure from commanding. This said, many compromises have been made in the way of a playable game that is challenging and involving for players.
You are not pushing a model and rolling dice. You are a Master and Commander in the Heat of Battle!