[2] Their engines were designed to produce a total of 11,000 indicated horsepower (8,200 kW) and a maximum speed of 17.5 knots (32.4 km/h; 20.1 mph) using steam provided by eight cylindrical boilers with forced draught.

The ships carried a maximum of 1,420 long tons (1,443 t) of coal, which gave them a range of 4,720 nautical miles (8,740 km; 5,430 mi) at a speed of 10 knots (19 km/h; 12 mph).

[3] Their main armament consisted of four breech-loading (BL) 13.5-inch (343 mm) guns mounted in two twin-gun barbettes, one each fore and aft of the superstructure.

On 16 February 1903, Royal Oak recommissioned at Portsmouth for service in the Home Fleet using part of the battleship Nile's crew as a nucleus.

In the summer of 1903, she participated in combined exercises in the Atlantic involving the Home, Mediterranean, and Channel Fleets, as well as the Cruiser Squadron.

[9] In April 1904, while operating with the Home Fleet off the Scilly Isles, Royal Oak and her sister ship Revenge had their bottoms lightly damaged when they struck a sunken wreck.

On 9 May 1904, Royal Oak became flagship of the Home Fleet's second-in-command, relieving her sister Empress of India, and took part in annual maneuvers in July and August.

On 7 March 1905, Royal Oak paid off at Portsmouth into the Chatham Reserve, and her crew transferred to the battleship Caesar.

The following day the ship recommissioned with a skeleton crew for service with the Sheerness-Chatham Division of the newly formed Fleet in Commission in Reserve at Home.

[12] As a unit of the First Division of the Blue Fleet, Royal Oak took part in annual maneuvers off the coast of Portugal and in the eastern Atlantic from 12 June to 2 July 1906.

In April 1909, Royal Oak and the other reserve ships with nucleus crews at Devonport were formed into the 4th Division of the Home Fleet.