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.^[3]

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.^[4] 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.^[4][5] This gave a speed of 28.5 kn (32.8 mph; 52.8 km/h).^[4]

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.^[4][5]

As built, Tjerk Hiddes 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.^[4][6] The ship had a sonar suite of Type 170B attack sonar and Type 162 bottom search sonar.^[4] The ship had a crew of 251.^[4]

Modifications edit

All six Van Speijks were modernised in the 1970s, using many of the systems used by the new Kortenaer-class frigates.^[4] The 4.5-inch gun was replaced by a single OTO Melara 76 mm and launchers for up to eight Harpoon anti-ship missiles fitted (although only two were normally carried). The hangar and flight deck were enlarged, allowing a Westland Lynx helicopter to be carried, while the Limbo mortar was removed, with a pair of triple Mk 32 torpedo launchers providing close-in anti-submarine armament. A Signaal DA03 radar replaced the DA02 radar and an American EDO Corporation CWE-610 sonar replaced the original British sonar.^[4][7][8] Tjerk Hiddes was modernised at the Den Helder naval dockyard between 15 December 1978 and 1 June 1981.^[7][8]

An order for four Van Speijks, including Tjerk Hiddes, was placed in 1962, with two more ordered in 1964.^[4] Tjerk Hiddes was laid down at the Amsterdam shipyard of Nederlandsche Dok en Scheepsbouw Maatschappij on 1 June 1964 and was launched on 17 December 1965. The ship was completed and entered service on 16 August 1967 with the pennant number F804.^[5][9]

In 1969 Tjerk Hiddes participated in the NATO exercises Razor Sharp and Peace Keeper and also served with STANAVFORLANT.^{[10][verification needed]}

On 27 August 1978 she was present at the Navy days at Portsmouth.^[2]

Tjerk Hiddes suffered from boiler problems, and in 1986 was put up for sale along with sister ships Van Speijk, Van Galen and Van Nes.^[8] The four ships then were purchased by Indonesia. Tjerk Hiddes was decommissioned on 6 January 1986 and transferred to the Indonesian Navy on 31 October 1986.^[11]

On 11 February 1986, Indonesia and the Netherlands signed an agreement for transfer of two Van Speijk class with option on two more ships.^[1] The ship was transferred to Indonesia on 31 October 1986 and renamed KRI Ahmad Yani on joining the Indonesian Navy, with the pennant number 351.^[11][1]

By 2002, the ships Seacat missiles were inoperable and it was reported that propulsion problems were badly effecting the availability of the ships of this class.^[12] The ship's Seacat launchers were therefore replaced by two Simbad twin launchers for Mistral anti-aircraft missiles, and Ahmad Yani was re-engined with two 10.9 megawatts (14,600 shp) Caterpillar 3616 diesel engines.^[1] As the Indonesian Navy retired Harpoon missile from its stockpiles, Ahmad Yani was rearmed with Chinese C-802 missiles.^[13]

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