Goblin ships, one heavy ship and 3 light ships. They are based on the Dromon of the Byzantine Empire.
As the ships are of Goblin make they don't have cannon, but do have Ballista's, and catapults, they also have trolls that can throw rocks, which is actually their most powerful weapon.
The Larger ship is Trireme with a larger number of weapons, although the main form of attack is to ram the enemy and send in the warbands to take the enemy ship.
Overall the fleet is small but looks effective, I have yet to play with it and will place any battle reports on Shackled to a Corpse.
The lighter craft are Biremes that still have a powerful ram but not as effective as the larger ship.