River Class - Naval Technology
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River Class

Vosper Thornycroft Shipbuilding has completed delivery of three River Class offshore patrol vessels for the UK Royal Nav




Royal Marine boarding party of 12 officers, 14 senior ratings, 22 junior ratings






Vosper Thornycroft Shipbuilding has completed delivery of three River Class offshore patrol vessels for the UK Royal Navy. The first of class, HMS Tyne (P281), entered service in January 2003, HMS Severn (P282) in June 2003 and HMS Mersey (P283) in December 2003. The River Class is deployed for fishery protection and other patrol missions around the United Kingdom.

The new River Class vessels replace five Island Class offshore patrol vessels which entered service in 1979. The 1,260t Island Class are being transferred to the Bangladesh Navy.

“The new River Class offshore patrol vessels replace five Island Class offshore patrol vessels which entered service in 1979.”

In February 2005, the UK Ministry of Defence placed a contract with Vosper for HMS Clyde, a River Class Batch 2 variant, to act as the Falkland Islands Patrol Vessel. HMS Clyde replaces the Castle Class HMS Leeds Castle and Dumbarton Castle OPVs.

It has an aft helicopter flight deck for up to Merlin-sized helicopters, a larger MSI-Defence Systems DS30B 30mm gun, BAE Systems Insyte combat data system, Terma Scanter 4100 I-band surveillance radar and Lockheed Martin Warship Electronic Chart Display and Information System (WECDIS) with WECDIS software from OSI Geospatial.

Construction began in October 2005 and the vessel was launched in June 2006. Sea trials began in December 2006 and HMS Clyde was commissioned in July 2007. It departed for the Falkland Islands in August 2007 and took over from Dumbarton Castle when it was decommissioned in November 2007.

The River Class vessels are just under 80m in length and have a full load displacement of 1,700t. The design was carried out by Vosper Thornycroft, assisted by Three Quays Marine.

The hull design gives very comfortable sea-keeping characteristics, even in high sea states, and the 4,125kW engine gives a full load maximum speed of 20kt in sea state 4. A semi-active stabiliser tank is installed for roll damping at all speeds, including when stationary. The vessels carry sufficient fuel, stores and water supplies for an endurance of 21 days.


Vosper Thornycroft submitted a proposal and tender to the UK Ministry of Defence in 2000 and 2001 and Vosper was awarded the contract in April 2001. Under the contractual lease arrangement, Vosper Thorneycroft financed the development and construction of the vessels, valued at £60m, and charters the vessels to the Ministry of Defence for five years.

In January 2007, the lease charter was extended for another five years, from 2008 to 2013. During the lease arrangement the VT Integrated Logistics division is responsible for providing logistic support and maintenance.


The vessels are of steel construction in a double chine hull form. The fine form ram bow has a very low wave-making resistance which gives fuel efficiency and comfortable sea-keeping characteristics.

“The hull design gives very comfortable sea-keeping characteristics, even in high sea states.”

The vessel typically has a complement of 28 but can accommodate a crew of 30 plus a Royal Marine boarding party of 18, comprising 12 officers, 14 senior and 22 junior ratings. Modular cabins, pre-fabricated and outfitted by VT, are either single or double berth and have en-suite facilities.

The working deck of HMS Tyne is sufficiently large to transport a number of smaller craft, wheeled or tracked light vehicles, or an LCVP landing craft.

The working deck can accommodate up to seven containers, enabling the ship to carry additional stores, workshops, mine countermeasure support containers, a diving recompression container or medical facilities. A heavy crane of 25t capacity is fitted to handle standard containers.

HMS Mersey and Severn have a flight deck for small / medium helicopters.


VT has designed an export version of the River Class for deployment in a wide range of operations connected with Exclusive Economic Zone (EEZ) protection, including disaster relief, anti-pollution, firefighting, rescue work and interception.

The flexibility of the OPV design allows an overall increase in length by insertion of a midship section to accommodate additional crew, equipment and facilities. By making special provision to put the ship’s propulsion and electrical machinery aft and all the normal crew accommodation in the forward section, the increase in overall length is achieved without a significant re-design.

The baseline export vessel includes a flight deck for land-based small / medium helicopters. The aviation facilities can be enhanced to handle larger helicopters or to provide storage and maintenance facilities for helicopters.


The River Class has a Robertson AP9 MkIII autopilot and is fitted with an integrated navigation and communications suite supplied by Marine Electronics Supplies.

The navigation suite includes a SafeMarine electronic chart display, Kelvin Hughes Nucleus navigation radar operating at I-band, a Leica MXXX420/2 global positioning system, a Raytheon Annschutz gyro compass and a Lilley and Gillie Sesterline Mk X magnetic compass, Fe700 echo sounder supplied by Furuno, Walker 7070 log and wind system, NAVTEX and a weather fax.

The River Class is equipped with a Rhode and Schwarz military communications suite operating in HF/VHF and UHF bands, Furuno maritime VHF communications set, INMARSAT-B satellite communications and GMDSS Area A3 military communications.

“The River Class offshore patrol vessels carry sufficient fuel, stores and water supplies for an endurance of 21 days.”


The vessel carries two Halmatic Jet Pacific 22 Rigid Inflatable Boats (RIB). River Class roll damping capability, provided by the semi-active stabiliser tank, is useful in RIB launch and recovery operations.

RIB launch and recovery can be carried out in wave conditions up to Sea State 5, with wave heights between 2.5m and 4m, using single-man operation, single-point lift davits. An RIB tracking system is also fitted.


The vessels carry a British Manufacturing and Research Company (BMARC) KAA 20mm gun and two general purpose machine guns.


The patrol vessel is powered by two Ruston 12 RK 270 medium speed diesel engines, rated at 4,125kW, 1,000rpm, which drive twin controllable pitch propellers. The auxiliary power suite comprises three 250kW Caterpillar engines and Newgate Stamford alternators. There are three 250kW main generators plus an emergency generator. A VTC control and monitoring system is fitted.

For berthing, station keeping and other fine control manoeuvering, the vessel is equipped with a Veth Motoren VT bow thruster rated at 280kW.

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