Royal Navy: What is the quirky surveillance ship RFA Proteus, how will she be used and why did the UK buy her?

The sophisticated surveillance ship sailed into Portsmouth last Friday (December 12), having previously visited the home of the Royal Navy on a few occasions. Much has been made of the Multi-Role Ocean Surveillance vessel since being a part of the fleet, with her projected role not only bolstering the Royal Fleet Auxiliary (RFA), but the security of the UK.

What is RFA Proteus?

The Royal Navy describes RFA Proteus as a Multi-Role Ocean Surveillance, with her being named after the son of Poseidon from Greek Mythology. Proteus is the God of rivers and bodies of water. She underwent a military conversion at the Cammell Laird shipyard in Birkenhead, Merseyside in 2023.

Formerly known as MV Topaz Tangaroa, the vessel was previously used as a platform supply vessel by P&O Maritime Logistics - supporting workers during construction projects and being used for subsea inspection and surveys. The then-Marshall Islands flagged vessel acted as a mother ship for Remotely Operated Vehicles (ROVs) during some missions, a role which she is expected to hold in a military capacity. The cost to convert her was roughly £70m. RFA Stirling Castle, previously known as MV Island Crown, is another commercial ship to go under a military conversion for a similar purpose.

How will RFA Proteus be used?

The ship will be crewed by two dozen Royal Fleet Auxiliary sailors, as well as 60 or so Royal Navy specialists. Underwater surveillance kit will be stored on board, but her main use will be to act as a launching pad for autonomous systems which the personnel will operate from the ship.

The Daily Express reported in September 2023 that she will be used to protect undersea cables in the North Sea, acting as the motor ship for submersible drones which can be used in difficult weather conditions. A senior source told the national publication that she would monitor 5,000 miles of oil and gas pipelines. A Royal Navy spokesman previously said the ship’s main task would be underwater surveillance.

RFA Proteus was sworn into service in London in October 2023, with the specialists on board being responsible for undersea surveillance, survey and warfare systems. She is equipped with a flight deck and a 1,000-square metre cargo deck, as well as a heavy-duty crane. Tests on how to launch autonomous vehicles from a launchpad were made in September this year, with SD Northern River acting as the role which RFA Proteus and Stirling Castle would fulfil.

Navy Lookout reported in August 2024 that RFA Proteus had not been used yet taken on any patrols of critical undersea infrastructure. Concern around protecting undersea infrastructure was heightened after Russia taskforces were seen sailing through The English Channel in November, with RFA Tideforce, HMS Iron Duke and other assets being deployed to shadow them, with the Type 23 frigate regularly on hand to protect national infrastructure in territorial waters.