You are a pirate on the high seas, well the seas are quite low right now, but they are getting rougher.

Every few seconds a new ship will appear, plunder it to take its booty, possibly recruit a new crewmate.  Or don't and your current crew will grow more accustomed to the seas.  Every time you successfully plunder a ship your crew will grow better at fighting and improve their morale.  If you choose not to recruit a new Crewmate after a successful plunder your crew will instead grow more loyal.