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River-class patrol vessel
45153648 river class.jpg
HMS Severn, HMS Mersey and HMS Tyne in February 2012.
Class overview
Name: River class
Builders: Vosper Thornycroft (now BAE Systems Surface Ships)
Operators:  Royal Navy
 Royal Thai Navy
Preceded by: Castle class
Subclasses: HMS Clyde, HTMS Krabi
In commission: June 2003
Completed: 5
Active: 5
General characteristics
Type: Patrol vessel
Displacement: 1,677 tonnes
Length: 79.5 metres
Beam: 13.6 metres
Draught: 3.8 metres
Installed power: 4,125 kW (5,532 hp) at 1,000 rpm
Propulsion: 2 × Ruston 12RK 270 diesel engines
Speed: 20 kn (37 km/h)
Range: 7,800 nautical miles (14,400 km) at 12 knots (22 km/h)
Boats & landing
craft carried:
2 × rigid inflatable boats
Complement: 30, accommodation for 20 more
  • 1 × 20 mm gun
  • 2 × general purpose machine guns

The River class is a British class of five offshore patrol vessels. Three were built for the Royal Navy, replacing the seven ships of the Island class, along with a fourth, a modified vessel based on the River class which replaced the Castle class, for duties in the Falklands. They are primarily used in the fisheries protection role. A fifth was built for the Royal Thai Navy.

Ships in class

Name Pennant No. Builder Launched Commissioned Decommissioned Recommissioned Status
River-class patrol vessel (Royal Navy)
Batch 1
Tyne P281 VT Shipbuilding, Southampton 27 April 2002 4 July 2003 24 May 2018 25 July 2018 In active service
Severn P282 4 December 2002 31 July 2003 27 October 2017 To be reactivated
Mersey P283 14 June 2003 28 November 2003 In active service
Modified Batch 1
Clyde P257 VT Shipbuilding, Portsmouth 14 June 2006 30 January 2007 In active service
Batch 2
Forth[1] P222 BAE Systems, Glasgow 20 August 2016 13 April 2018[2] In active service
Medway[1] P223[3] 23 August 2017 2019[4] Awaiting commissioning
Trent[1] P224[3] 20 March 2018 2019[4] Sea Trials
Tamar[5] P233[6] 10 October 2018 2021[4] Fitting out
Spey[5] P234[7] 19 June 2019 2021[4] Fitting out
Amazonas-class corvette (Brazilian Navy)
Amazonas P120 BAE Systems, Portsmouth 18 November 2009 29 June 2012 In active service
Apa P121 BAE Systems, Scotstoun 15 July 2010 30 November 2012 In active service
Araguari P122 16 July 2010 21 June 2013 In active service
Krabi patrol vessel (Royal Thai Navy)
Krabi 551 Bangkok Dock Company 3 December 2011 26 August 2013 In active service
Prachuap Khiri Khan 552 2 August 2019 TBA Under construction


The ships are significantly larger than the Island-class vessels and have a large open deck aft allowing them to be fitted with equipment for a specific role, which can include fire-fighting, disaster relief and anti-pollution work. For this purpose, a 25 tonne capacity crane is fitted. In addition, the deck is strong enough for the transport of various tracked and wheeled light vehicles, or an LCVP.


Initially the three ships were not owned by the Royal Navy. They were constructed under an arrangement with the shipbuilder, Vosper Thornycroft (VT), under which the Royal Navy leased the vessels from the shipbuilder for a period of ten years. VT were responsible for all maintenance and support for the ships during the charter period. At the end of this, the Navy could then either return the ships, renew the lease or purchase them outright.

In September 2012, it was announced by the Defence Secretary Philip Hammond that the Ministry of Defence had purchased the vessels for £39 million.[8]

Running costs

Date Running cost What is included Citation
2009-10 £5 million "The average running cost per class of River Class is £20 million... These figures, based on the expenditure incurred by the Ministry of Defence in 2009-10, include maintenance, safety certification, military upgrades, manpower, inventory, satellite communication, fuel costs and depreciation." [9]

Modified River class

Clyde off the Falkland Islands

HMS Clyde: A modified fourth vessel, HMS Clyde, constructed at Portsmouth Dockyard, replaced the two vessels of the Castle-class for duties in the Falkland Islands. This ship displaces 1,850 tonnes and has a 30mm gun, as well as a deck strengthened for aircraft operations.

HTMS Krabi: Another vessel was built for the Royal Thai Navy called HTMS Krabi. This ship was built in Thailand but designed by BAE Systems. On this ship the main gun was changed to a 76mm gun.

HMS Severn, Portsmouth 2013

Brazilian Navy

The Brazilian Navy's Amazonas-class corvettes, built by BAE in the United Kingdom, are based on the River-class design.

2013 Royal Navy order

On 6 November 2013 it was announced that the Royal Navy has ordered three further modified River-class vessels, to replace HM Ships Tyne, Severn and Mersey. The new batch is to be built at BAE's Clyde shipyards and will feature helicopter landing facilities. The first of the new ships is expected to enter service in 2017.[10]


External links

Mersey departing Portsmouth Naval Base on 12 November 2008

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