KRI Oswald Siahaan (354)

In the early 1960s, the Royal Netherlands Navy had an urgent requirement to replace its Van Amstel-class frigates, obsolete ex-American escorts built during the Second World War. To meet this requirement, it chose to build a modified version of the British Leander-class frigate as its Van Speijk class, using broadly the same armament as the original design, but where possible, substituting Dutch electronics and radars.[1]

The Van Speijks were 113.4 m (372 ft) long overall and 109.7 m (360 ft) between perpendiculars, with a beam of 12.5 m (41 ft) and a draught of 5.8 m (19 ft). Displacement was 2,200 long tons (2,200 t) standard and 2,850 long tons (2,900 t) full load.[2] Two Babcock & Wilcox boilers supplied steam to two sets of Werkspoor-English Electric double reduction geared steam turbines rated at 30,000 shp (22,000 kW) and driving two propeller shafts.[2][3] This gave a speed of 28.5 kn (32.8 mph; 52.8 km/h).[2]

A twin 4.5-inch (113 mm) Mark 6 gun mount was fitted forward. Anti-aircraft defence was provided by two quadruple Sea Cat surface-to-air missile launchers on the hangar roof. A Limbo anti-submarine mortar was fitted aft to provide a short-range anti-submarine capability, while a hangar and helicopter deck allowed a single Westland Wasp helicopter to be operated, for longer range anti-submarine and anti-surface operations.[2][3]

As built, Van Nes was fitted with a Signaal LW-03 long range air search radar on the ship's mainmast, with a DA02 medium range air/surface surveillance radar carried on the ship's foremast. M44 and M45 fire control radars were provided for the Seacat missiles and ships guns respectively.[2][4] The ship had a sonar suite of Type 170B attack sonar and Type 162 bottom search sonar.[2] The ship had a crew of 251, later reduced to 180.[2][5]

The ship was previously operated by the Royal Netherlands Navy as the Van Speijk-class frigate HNLMS Van Nes (F805). Van Nes was laid down on 25 July 1963, launched on 26 March 1966, commissioned on 9 August 1966 and decommissioned in February 1987, and was transferred to Indonesia on 31 October 1988 where it received its current name.[10][5]

In May 2016, Oswald Siahaan seized a Chinese trawler, the Gui Bei Yu (27088), in the waters of Natuna Islands, firing shots at the trawler and blocking an attempt by a Chinese coast guard ship to rescue the fishing ship - which was taken under Indonesian custody.[11]

• Blackman, Raymond V. B., ed. (1971). Jane's Fighting Ships 1971–72. London: Sampson Low Marston & Co., Ltd. ISBN 0-354-00096-9.
• Couhat, Jean Labayle; Baker, A. D., eds. (1986). Combat Fleets of the World 1986/87. Annapolis, Maryland, USA: Naval Institute Press. ISBN 0-85368-860-5.
• Gardiner, Robert; Chumbley, Stephen, eds. (1995). Conway's All The World's Fighting Ships 1947–1995. Annapolis, Maryland, USA: Naval Institute Press. ISBN 1-55750-132-7.
• Moore, John, ed. (1979). Jane's Fighting Ships 1979–1980. London: Jane's Yearbooks. ISBN 0-354-00587-1.
• Moore, John, ed. (1984). Jane's Fighting Ships 1984-85. London: Jane's Yearbooks. ISBN 978-0710607959.
• Prézelin, Bernard; Baker, A. D., III, eds. (1990). The Naval Institute Guide to Combat Fleets of the World 1990/1991. Annapolis, Maryland, USA: Naval Institute Press. ISBN 0-87021-250-8.
• Saunders, Stephan, ed. (2009). Jane's Fighting Ships 2009-2010. Jane's Information Group. ISBN 978-0-7106-2888-6.