Thetis was a three-masted, ship-rigged frigate that had a sail area of 2,370 square metres (25,500 sq ft).

The ship was considered to be a very good sea boat and very manoeuvrable, although she did suffer from severe pitching.

[3] Thetis was designed by Read, Chatfield and Creuze and she was the only ship of her class, which was approved on 16 March 1843.

She was launched on 21 August 1846 and duly commissioned for service on 30 December 1846, having cost £40,605, this rising to £51,926 to have her fitted for sea.

[2] In February 1847 she ran aground at Lisbon, Portugal, and was ordered to Plymouth, Devon for repairs.

Her internal equipment was removed and she served as a coal hulk at Kiel, eventually being broken up there in 1894–95.