River-class patrol vessel
||This article needs additional citations for verification. (May 2011)|
HMS Severn, HMS Mersey and HMS Tyne in February 2012.
|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|
|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
|2 × rigid inflatable boats|
|Complement:||30, accommodation for 20 more|
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 
|Tyne||P281||Vosper Thornycroft||27 April 2002||4 July 2003|
|Severn||P282||Vosper Thornycroft||4 December 2002||31 July 2003|
|Mersey||P283||Vosper Thornycroft||25 June 2003||28 November 2003|
|Royal Navy modified River class|
|Clyde||P257||Vosper Thornycroft||14 June 2006||30 January 2007|
|Krabi||Bangkok Dock & BAE Systems Surface Ships||3 December 2011||2013|
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.
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."|||
Modified River class 
A modified fourth Batch II 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 30 mm gun, as well as a deck strengthened for aircraft operations.