River-class offshore patrol vessels HMS Tamar and HMS Spey arrive in California.

According to a tweet published by Chris Cavas on October 12, 2021, Royal Navy's River-class offshore patrol vessels HMS Tamar and HMS Spey arrived at San Diego en route to the western Pacific.
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River-class Offshore Patrol Vessel HMS Tamar (Picture source: Twitter account of Chris Cavas)

HMS Tamar is a Batch 2 River-class offshore patrol vessel of the British Navy. Named after the River Tamar, she is the fourth Batch 2 River-class vessel to be built and was formally commissioned on 4 June 2020

The River Class patrol ships can be used for anything from fire-fighting to disaster relief operations. There are 4 in all; HMS Tyne, HMS Mersey and HMS Severn and HMS Clyde. HMS Clyde operates around the Falkland Islands in the South Atlantic. Tyne, Mersey and Severn have a crew of about 45 sailors, working at least 275 days a year at sea enforcing British and European fisheries law.

The Batch 2 River-class ships are fundamentally different in appearance and capabilities from the preceding Batch 1. Notable differences include the 90.5 metres (296 ft 11 in) long hull, a top speed of 24 knots (44 km/h; 28 mph), Merlin-capable flight deck, a displacement of around 2,000 tonnes and greatly expanded capacity for accommodating troops.

The Batch 2 River-class ships also have a different (full width) superstructure and a fundamentally different above-water hull form shape. The class is also fitted with the Kelvin Hughes SharpEye integrated radar system for navigation, the Terma Scanter 4100 2D radar for air and surface surveillance, and a BAE CMS-1 Combat Management System.

The Batch 2 River-class is powered by 2 × MAN 16V28/33D diesel engines developing 14,700kW/19,700HP. It is armed with one Bushmaster 30 mm cannon, two Miniguns and two General purpose machine guns.