Preparations underway for new UK subsea infrastructure protection ship

4C Offshore | Tom Russell
By: Tom Russell 20/01/2023 Ministry of Defence

The UK Ministry of Defence revealed Britain’s critical subsea infrastructure will be supported by the first of two future undersea surveillance ships today arrived into Birkenhead. Once operational, the ship will be dedicated to safeguarding subsea cables and oil and gas pipelines.  


The 98-metre-long vessel, previously operated by P&O Maritime Logistics, will be be renamed as it joins the RFA fleet. Currently known as
Topaz Tangaroa, it was selected to meet the requirements of the Royal Navy having been built four years ago to support a mix of underwater operations in the offshore energy sectors, including offshore wind.

The 6,000 ton vessel is equipped with a helipad, crane, and expansive working deck and features a ‘moon pool’ – a large access point in the underside of the hull through which submersible capabilities can be launched. It will act as a ‘mother ship’, operating remote and autonomous offboard systems for underwater surveillance and seabed warfare.

Shortly after arriving at Cammell Laird, the ship will be repainted and have critical military equipment installed, before taking up its role as the first of two Multi-Role Ocean Surveillance (MROS) ships, operated by the Royal Fleet Auxiliary (RFA) later this year.


The vessel will be formally handed over to control of the RFA in the next few days, several months ahead of schedule – following an acceleration of the acquisition announced by the Defence Secretary in November 2022.


The vessel will be crewed by around two-dozen RFA sailors, while around 60 Royal Navy specialists will operate the undersea surveillance systems and other survey and warfare systems when embarked.


Defence Secretary, Ben Wallace, said: "The first of two dedicated subsea surveillance ships will join the fleet this Summer, bolstering our capabilities and security against threats posed now and into the future.  


It is paramount at a time when we face Putin’s illegal invasion of Ukraine, that we prioritise capabilities that will protect our critical national infrastructure."


Head of the Royal Fleet Auxiliary, Commodore David Eagles RFA, said: "This is an entirely new mission for the Royal Fleet Auxiliary – and one we relish.


"We have been entrusted with supporting a key operation to safeguard the UK’s infrastructure, security and prosperity and that fills all of us in the RFA with pride. These are really exciting times."

DE&S Director General Ships Vice Admiral Paul Marshall said: "DE&S worked at pace to successfully accelerate the purchase and delivery of the first ship under the critical MROS programme. We continue to work with agility to support the UK MOD in addressing both the current and future threats posed by an ever-changing world.


Since the attack on Nord Stream, there has an been an increase in efforts to ensure the integrity and security of the UK's network of subsea infrastructure. The new vessel is due to enter operational service in Summer this year, with the programme for the acquisition of a second ship currently in concept phase.