Narrow Seas: A Scenario Generator and Campaign for Small Actions in the Age of Sail is a generic version of the scenario generator and campaign rules for Captaincy.
It's a meta-game that supplements whatever Age of Sail rules you currently use.
It depicts small fight-or-flight encounters between patrols, cargo ships, and raiders, using novel terrain generation and scoring rules to make these encounters very different from fleet battles.
—description from the publisher