RFA Proteus

RFA Proteus is a ship of the Royal Fleet Auxiliary within His Majesty's Naval Service of the United Kingdom. Its roles being a platform for Remotely Operated Underwater Vehicles (ROUVs) and a testbed for new specialist capabilities, required for monitoring waters important to UK interests. Acquired in 2023, the ship entered drydock at Cammell Laird for modification into a Multi-Role Ocean Surveillance Ship (MROSS). She formally entered service in October 2023.

The ship was formerly named MV Topaz Tangaroa in 2017–2022, and was used as a platform supply vessel operated by P&O Maritime Logistics. The vessel was refitted after being sold to the U.K. Ministry of Defence in January 2023.

Proteus is one of two new commercial vessels acquired for the Royal Fleet Auxiliary in 2023, the other being RFA Stirling Castle; a mine hunting support ship to act as a mothership for autonomous minehunters.

MV Topaz Tangaroa
The ship operated as the offshore support vessel MV Topaz Tangaroa for Topaz Marine (later, P&O Maritime Logistics) from December 2019 until January 2023. Designed and built by Vard Brattvaag, Norway and with the hull construction completed in Tulcea shipyard, Romania the primary capabilities of Topaz Tangaroa were to support subsea construction and installation projects, subsea inspection and survey, and as a mother ship to support remotely operated vehicle (ROV) operations. The ship was flagged in the Marshall Islands with its home port as Majuro.

Projects for which Topaz Tangaroa was deployed includes supporting the construction of the Greater Changhua offshore wind farm near Taiwan.

RFA Proteus
Owing to the UK's government's growing concern about protecting subsea infrastructure, and the 2022 Russian invasion of Ukraine, Topaz Tangaroa was purchased by the UK's Ministry of Defence in February 2023 for £70 million to be converted into a multi-role ocean surveillance (MROS) ship operated by the Royal Fleet Auxiliary. The ship was assigned the pennant number K60. Initial conversion for naval service is being conducted at the Cammell Laird shipyard in Birkenhead, UK.

The MROS was initially announced by the Defence Secretary Ben Wallace during the 2022 Conservative Party conference. Then-Prime Minister Boris Johnson had first discussed the possibility of such a vessel in November 2020.

She is equipped with a 120 tonne crane as well as a hangar and workshops capable of accommodating remotely operated and other unmanned underwater vehicles (UUVs). The Ministry of Defence reportedly acquired three Kongsberg HUGIN Large UUVs which reportedly can conduct surveillance and surveys down to depths of 6000 m.

Conversion of Proteus was completed in September 2023 and the ship began post-conversion sea trials. She formally entered service with the Royal Fleet Auxiliary in October 2023. A formal dedication ceremony took place in London on the River Thames, in the presence of the RFA Commodore-in-Chief, Prince Edward, Duke of Edinburgh, and Akshata Murty, wife of the incumbent Prime Minister Rishi Sunak, who will be the ship's sponsor throughout its active life, with Proteus berthed alongside the Imperial War Museum's preserved Town-class cruiser (1936) light cruiser, HMS Belfast (C35).

Design and facilities
RFA Proteus is a former offshore support vessel, Vard designed, the hull was constructed at their Tulcea shipyard in Romania and then fitted out at their Brattvåg facility in Norway, completed in 2019. Intended for work in the offshore oil industry its role was supporting relative construction, maintenance and inspection work and was already equipped to operate Autonomous Underwater Vehicles (AUVs).

The ship is capable of a top speed of 14 knots, but it has a typical cruising speed of 11 knots. It is equipped with 5 x Caterpillar diesel engines, these required to supply power for the ship, along with the stern azimuth thrusters, the twin bow tunnel thrusters and a drop-down azimuth bow thruster. It also has a Rolls-Royce Icon Dynamic Positioning system Class II, which enables the ship to remain stationary and includes an assigned operating control which overlooks the rear working deck. Proteus is designed with Antiroll tanks, including pumps capable of moving ballast water between them, which counters any horizontal motion.

The ship's accommodation comprises fifty-three cabins with eighty-two bunks, these are split across twenty-four single cabins and twenty-nine double cabins. A Royal Fleet Auxiliary crew of twenty-six will operate Proteus. This will be supplemented with approximately sixty Royal Navy specialists, who will be responsible for the undersea surveillance, survey and warfare systems operations. The ship is equipped with a single cafeteria but there are several mess and lounge spaces for crew relaxation.

The ship has a 7.2m2 opening moon pool enabling underwater vehicles to enter into or leave the water easily within a protected environment. This facility is located at the forward end of the working deck and the hatch cover is removed by crane. The AHC crane has a 3,000 m long wire which enables objects to be directly lowered to the seabed. It has a safe working load of up to 120 tonnes and the working / cargo deck can carry loads totalling up to 1,400 tonnes. The size of the working / cargo deck is 1,000m2 and Proteus is also equipped with a flight deck.

There is hangar space for Remotely Operated Vehicles (ROV)s, which runs across the ship for easy access between the port and starboard systems and the Launch and recovery system (LARS) can lower the underwater vehicles over either side. Proteus has an umbilical tether winch system, which carries the control, power and communications cables for equipment lowered, this comes from drums below decks and then up to the hangar, before connecting to the ROV through the LARS. Adjacent to the hangar are ROV workshops.

Proteus is fitted with a multibeam echosounder (MBES) giving the ship a hydrographic capability and it has a number of work spaces available which could be used for operations rooms.

Career and Operations
As of December 2023, it was reported that Proteus was not yet available for operations having yet to complete Operational Sea Training and being still required to return to Cammell Laird shipyard in the new year for dry docking and inspections. Pursuant to the completion of work, Proteus reportedly sailed from Cammell Laird in March 2024 to resume her work-up. It visited London during the second weekend of May 2024. She is currently in Devonport Dockyard in Plymouth as of June 2024.