"Warrior" was reclassified as a "screw battle ship, third class, armoured" in 1887 and again in May 1892 as a first-class armoured cruiser, although no changes were made to her. She was considered for modernization as late as 1894, but this was rejected as uneconomical after at least one new boiler was installed. She was struck off the effective list at Portsmouth and classified as hulk in March 1900. The ship was used as a storage hulk from May 1901 to July 1902. In preparation for her service as a depot ship for a flotilla of destroyers, the ship had her engines and boilers removed and part of her upper deck roofed over. "Warrior" served in this role from July 1902, under the command of Captain John de Robeck. In March 1904, she was assigned to the Portsmouth-based , the Royal Navy's torpedo-training school. Her name was changed to "Vernon III" that month and six new Belleville boilers and four electric generators were installed so that she could supply steam and electricity to the neighbouring hulks that made up "Vernon". Most of the upper deck was roofed over to form classrooms for radio training, and her fore and mizzen masts were reinstalled. In October 1923, the school was transferred to a newly built shore installation, rendering "Warrior" and her companion hulks redundant; "Warrior" resumed her name on 1 October and the Royal Navy declared her redundant six months later.