Knarr

Cog is one of the Airships that the player can purchase at Shipwright for.

Trivia
Before 1.2 update, Knarr was the default Airship that the player started a new game with. If the player bought a different Airship, they could never get the starting Airship again in the same world.

Achievement
Buying an Airship at a Shipwright for the first time awards the achievement: