The protagonist's ship in Assassin's Creed IV: Black Flag is the Jackdaw.
Edward Kenway acquires the vessel early in the story and uses it to travel throughout the Caribbean. The Jackdaw is both a mobile base and a major gameplay system: players can upgrade its hull, broadside cannons, mortars, storage, and other equipment as the campaign progresses.
The ship supports exploration, naval combat, boarding actions, treasure hunting, and travel between islands. Its development mirrors Edward's rise from opportunistic privateer toward a more committed participant in the Assassin–Templar struggle.
The Aquila is the ship associated with Connor in Assassin's Creed III, while the Morrigan belongs to Shay Cormac in Assassin's Creed Rogue. Guanahaní is connected with early exploration in the series but is not Edward's main ship. These names make useful comparisons, but only the Jackdaw is Black Flag's player vessel.