Exclusive to: Shipwrecked.
A Boat Cannon is a Weapon introduced in the Shipwrecked DLC. It requires 5 Logs, 4 Gunpowder and 6 Coconuts to craft and a Science Machine to prototype. It can only be used while attached to a Boat's light slot. It does 100 damage and uses 6.66% of its durability per shot, allowing 15 shots per cannon.
In Shipwrecked worlds, Nitre, an ingredient of Gunpowder, is not renewable. Despite this, Boat Cannons can be renewed by giving Lobster Dinner to Yaarctopus, using the Slot Machine to obtain Gunpowder, or by digging up an X Marks the Spot. Players can also go through the Seaworthy to the base game world and get renewable Nitre from Caves during Earthquakes.