Island Mayhem is a set of rules for playing games in which 25mm – 28mm Pirates are searching for treasure.
Fleet of Battle is a set of free wargames rules for playing out battles between fleets of ancient galleys. Think Ben Hur. There also are several pages of free print-and-play galleys for use in lieu of lead miniatures. The rules require a knowledge of the commercial Field of Battle wargames rules.
Ironclad Draughts is a set of one-page rules for playing out battles between ironclads.
Hunters on the Shoreline is a set of free wargames rules for playing WWII coastal naval actions using 1/600 miniatures. It’s available from PT Dockyards.