In Britain the Royal Navy has developed a new class of undersea surveillance ships that are based on 6,000-ton existing oil rig support ships with a top speed of 21 kilometers an hour. Cruising speed is about half that. Only a few minor modifications of the original ship are required to meet Royal Navy requirements. This first one to be militarized is only four years old. These ships come with a helipad, a crane, a large work deck and a central moon pool in the bottom of the hull from which submersible operations can be launched. As civilian vessels these ships supported the construction, repair and inspection of offshore oil rigs. As military ships the concentration will be on the inspection and repair of seabed communications cables and pipelines. Underwater salvage of sunk ships can also be carried out with the addition of specialized submersibles that can operate from the ship. In this respect the ship operates as a mother-ship for smaller submersibles, some of them operated remotely, to undertake inspections, repairs and sometimes offensive operations on enemy undersea cables and pipelines.
These undersea surveillance ships are operated by the Royal Fleet Auxiliary or RFA, the fleet logistics arm, and have a crew of 84. While 24 of the crew belong to the RFA, the rest are Royal Navy sailors who operate and maintain the undersea surveillance systems as well as other underwater survey and warfare equipment. The major military addition to these ships is a $25 million dollar remotely operated deep-water salvage submersible.
The first of these ships will enter service in mid-2023 with the second to follow a year later. Each will require a warship escort on most missions. Such would have been the case in early 2022 when the Nordstream underwater natural gas pipeline from Russia to Germany was damaged or sabotaged. These two new ships will operate worldwide to inspect and repair undersea cables and pipelines Britain and its NATO allies depend on.