The Derrickhand is responsible for setting up, operating, maintaining, and dismantling derrick hoisting and drilling fluid circulating systems on a drilling rig. This role involves aligning and manipulating tubulars to assist in making up and breaking out drill and casing strings, as well as mixing and monitoring drilling fluid during operations. The Derrickhand also maintains inventories of drilling fluid components and mud pump parts, ensuring the integrity and functionality of the rig's systems.