River-class

The River class consists of offshore patrol vessels (OPVs) built primarily for the United Kingdom's Royal Navy to replace the Island and Castle classes. Construction of the initial Batch 1 vessels began in 2001 under Vosper Thornycroft. The Royal Navy originally operated these vessels under a lease agreement before the Ministry of Defence purchased the fleet in 2012. A second iteration, Batch 2, was produced by BAE Systems starting in 2014. The design has been adapted for international operators, including the Brazilian Navy, the Royal Thai Navy, and the Royal Bahrain Naval Force.

Batch 1 vessels feature an open aft deck equipped with a crane to support fire-fighting, disaster relief, and anti-pollution equipment. This deck is rated for light tracked or wheeled vehicles and landing craft. The modified Batch 1 vessel and all Batch 2 ships incorporate a flight deck capable of operating Merlin helicopters. Batch 2 vessels utilize a different hullform with increased bow flare and a full-width superstructure. Technical systems include the Kelvin Hughes SharpEye navigation radar, Terma Scanter 4100 2D radar, and the BAE CMS-1 Combat Management System. These ships employ the Shared Infrastructure operating system, which uses virtual technology to integrate sensors and weapons. For specialized tasks, Batch 2 ships can embark unmanned underwater vehicles for mine countermeasures or small unmanned aerial vehicles.

In the Royal Navy, Batch 1 ships are assigned to the Coastal Forces Squadron for fishery protection, border patrol, and EEZ security within UK waters. Although previously scheduled for decommissioning, three Batch 1 vessels were retained to maintain maritime control following the United Kingdom’s withdrawal from the European Union. Batch 2 ships are utilized for forward presence roles, stationed overseas with rotating crews to conduct maritime security, counter-piracy, and anti-smuggling operations. Active deployments include the Falkland Islands, the Caribbean, and the Mediterranean, where vessels are based in Gibraltar to operate in the Gulf of Guinea. Two Batch 2 vessels are forward-deployed to the Indo-Pacific region for a projected duration of five to ten years.

International service includes the Brazilian Amazonas class, developed from the Batch 1 design. The Royal Thai Navy operates two vessels, with the second ship, Prachuap Khiri Khan, fitted with anti-ship missiles. The former Royal Navy vessel Clyde was transferred to the Royal Bahrain Naval Force in 2020. All Batch 2 vessels in Royal Navy service have received a dazzle camouflage paint scheme.