Hope it helps
quote from F.A.Q.
Q: How will ships and naval warfare work?
A: Ships can be purchased from Harbour Master NPCs in any of the coastal towns. Each race has several unique ships that they can load with units, siege weapons, livestock, and resources and travel the seas in search of trade or PvP warfare and to gain access to the island towns. Naval Warfare will come down to what units you have in your fleet. Archers and ranged siege weapons will be able to fire at other fleets and your melee units can board
enemy ships to carry out the fight. Select naval units, such as the Elven Kraken, will be able to fight but not transport units or goods.