So far there are only two types of ship weapons: Cannons and swivel guns. The swivel gun does little damage with little area damage but it's cheap. The cannons however, have superior range, increased damage, and a large area of effect. They are more expensive and if too many shots are fired at a ship, the ship will sink, drowning the enemy and their treasure, but still leaving you the option to plunder. When you have a ship weapon you need a cannoneer. You can either hire a cannoneer from a tavern or you can teach the Cannon Mastery skill to one of your crew mates or captain. On top of everything you need ammo. You can buy ammo at the shipwright for 95g for every 5 bombs. To load and fire the cannon, your cannoneer needs to grab ammo from the ammo pile (that is placed on the ship) and carried from the ammo pile to the cannon and fired within a second of loading.