Archimedes made her maiden voyage, from London to Sheerness near the mouth of the Thames, commencing 2 May 1839.[20] On the 15th, she commenced her first sea voyage, from Gravesend to Portsmouth, which was completed at the unexpectedly high speed of 10 knots. At Portsmouth, Archimedes was successfully trialed against one of the swiftest vessels then in Admiralty service, HMRC Vulcan, in the presence of some senior Navy officials, who were impressed by Archimedes' performance.[12]