 Further storage space was required, and six hulks were moored alongside to serve as floating magazines; they remained even after a further magazine had been built ashore (1857).These storage problems were only alleviated when a further five large magazines, guarded by a barracks, were built inland at Chattenden (these were linked to Upnor via a 2 ft 6in (76 cm) narrow-gauge line built for steam locomotives).In 1891, the castle and its associated depot came under the full control of the Admiralty, ending an arrangement in which the War Office had managed the site with the Admiralty providing the funding.