"Galatea" had a length between perpendiculars of , a beam of and a draught of . Designed to displace , all of the "Orlando"-class ships proved to be overweight and displaced approximately . The ship was powered by a pair of three-cylinder triple-expansion steam engines, each driving one shaft, which were designed to produce a total of and a maximum speed of using steam provided by four boilers with forced draught. The ship carried a maximum of of coal which was designed to give her a range of at a speed of . The ship's complement was 484 officers and enlisted men.