A drum for storing an electrically conductive tether having a first end secured to an aerial vehicle and a second end secured to a ground station that includes a drum frame rotatable about a drum axis, a drum surface positioned over the drum frame comprising a spiral extrusion wrapped around the drum frame, wherein the extrusion has a cross-section having an upper surface that is shaped to conform to an outer surface of the electrically conductive tether, and wherein the extrusion is adapted for dissipating heat generated through a transfer of electricity from the aerial vehicle to a ground station through the electrically conductive tether.