Proteus-class

RFA Proteus (K60) is a Multi-Role Ocean Surveillance Ship (MROSS) of the Royal Fleet Auxiliary, operating within His Majesty's Naval Service of the United Kingdom. The ship began life as the offshore support vessel MV Topaz Tangaroa, a VARD 3 08 design launched on 18 March 2017. Her hull was built at Vard's Tulcea shipyard in Romania and fitted out at the company's Brattvåg facility in Norway, with completion in 2019. Flagged in the Marshall Islands with Majuro as her home port, she worked for Topaz Marine and later P&O Maritime Logistics from December 2019 until January 2023, supporting subsea construction, inspection and survey tasks and acting as a mother ship for remotely operated vehicles. Among her commercial deployments was support to cable installation for the Greater Changhua offshore wind farm off Taiwan.

The MROSS requirement was raised by Prime Minister Boris Johnson in November 2020 and announced by Defence Secretary Ben Wallace at the 2022 Conservative Party conference, driven by British concern over subsea infrastructure and the 2022 Russian invasion of Ukraine. The Ministry of Defence bought Topaz Tangaroa on 14 February 2023 for £70 million and had her converted at Cammell Laird in Birkenhead. Conversion finished in September 2023 and Proteus entered service on 10 October 2023, with a dedication ceremony on the River Thames attended by the RFA Commodore-in-Chief, Prince Edward, Duke of Edinburgh, and the ship's sponsor Akshata Murty, the vessel berthed alongside the preserved Town-class cruiser HMS Belfast. She was one of two commercial ships acquired for the Royal Fleet Auxiliary that year, the other being the minehunting mothership HMS Stirling Castle (M01).

Propulsion is by five Caterpillar diesel engines — two 3516C, one 3512C and two C32 units — driving two Kongsberg azimuth thrusters, with twin bow tunnel thrusters and a drop-down azimuth bow thruster. A Rolls-Royce Icon Class II dynamic positioning system, controlled from a station overlooking the after working deck, holds the ship on station, and anti-roll tanks with transfer pumps damp motion. The working deck covers 1,000 m² and takes loads of up to 1,400 tonnes; a 7.2 m² moon pool at its forward end allows underwater vehicles to be deployed in shelter. An active heave-compensated crane with a 3,000 m wire has a safe working load of 120 tonnes. A hangar running athwartships houses remotely operated vehicles, served by adjacent workshops, an umbilical tether winch system fed from below-deck drums, and launch and recovery systems on both sides. Proteus carries a multibeam echosounder for hydrographic work, a flight deck, and spaces convertible to operations rooms. The Ministry of Defence acquired three Kongsberg HUGIN Large UUVs, reported capable of survey and surveillance to 6,000 m. Accommodation comprises 53 cabins with 82 bunks.

Proteus had not completed Operational Sea Training by December 2023 and returned to Cammell Laird for docking, sailing again in March 2024 to resume her work-up. She visited London in May 2024, lay at Devonport in June, returned to Birkenhead by October and departed late that month. In November 2024 the Ministry of Defence released a photograph of Proteus shadowing the Russian research ship Yantar.