Initially, "Ranger" was designed as a flush-decker, like "Langley", with nothing extending above the flight deck. Keeping the flightdeck clear of obstacles complicated the arrangement of machinery. The smoke from her six boilers was vented up six small stacks, with three on each side of the aft hangar. The stacks were hinged and were rotated to a position parallel with the hangar deck during flight operations. The unusual stack arrangement is a carry-over from her flush-deck design. When an island was added midway through construction, rebuilding the uptakes into the island was rejected as too costly.