The Karel Doorman-class frigates are a series of eight multi-purpose vessels built for the Royal Netherlands Navy. Its namesake is Karel Doorman, a Dutch naval officer whose ship was struck by a Japanese torpedo in the battle of the Java Sea in 1942, and who, as a result of which, went down with his ship.

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Quick Facts Class overview, General characteristics ...

HNLMS Van Amstel (F831)
Class overview
Name	Karel Doorman class
Builders	Damen Schelde Naval Shipbuilding
Operators	Royal Netherlands Navy  Belgian Navy  Chilean Navy  Portuguese Navy
Preceded by	Netherlands: Kortenaer class / Roofdier class Belgium: Wielingen class Portugal: João Belo class
Succeeded by	Netherlands & Belgium: ASWF class
Cost	ƒ445 million per unit[1]
Built	1985–1995
In commission	1991–present
Completed	8
Active	7
Laid up	1
General characteristics
Type	Multi-purpose frigate
Displacement	3,320 tons
Length	401 feet (122 m)
Beam	47 feet (14 m)
Draught	20 feet (6.1 m)
Propulsion	CODOG-propulsion 2 × Rolls-Royce Spey 1A, 16,700 hp (12.4 MW) gas turbines 2 × Stork-Werkspoor 12SW280- 4,895 hp (3.7 MW) + 4 Stork DRO 218K diesel engines
Speed	30 knots (56 km/h)
Complement	154
Sensors and processing systems	Thales Smart-S Mk.1 long-range 3D surveillance and tracking radar Thales LW08 long-range surveillance radar Thales SeaWatcher 100 active phased array surface detection and tracking radar (NLD and BE ships only) Thales GateKeeper Electro-optical 360° survaillance system (NLD and BE ships only) Thales STIR 1.8 Tracking and Illumination Radar system Thales Scout surface surveillance and tactical navigation radar Thales PHS-36 hull-mounted sonar Thales Anaconda DSBV 61 VLF passive tactical towed array sonar Ultra Electronics Multi-static Low Frequency Active Passive Sonar (NLD ships only)
Electronic warfare & decoys	Thales Vigile APX Radar electronic support measures Mark 36 SRBOC
Armament	16 × RIM-7 Sea Sparrow anti-air VLS 8 × Boeing Harpoon anti-ship missile 2–6 × FN MAG 7.62 mm machine gun 2–4 × Browning M2 12.7 mm machine gun 2 × Twin-Mark 46 torpedo tubes 1 × OTO Melara 76 mm gun 1 × Goalkeeper CIWS
Aviation facilities	Hangar and flight deck

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In the 1970s, Dutch naval authorities deemed the Roofdier-class frigates old, outdated, and therefore in need of replacement. This led to the construction of the Karel Doorman-class frigates in the mid 1980s after the Dutch navy had finalised the design and requirements for the frigates at the end of the 1970s and early 1980s.^[2]

The design of the M-frigates was made in-house at the Royal Netherlands Navy, in close collaboration with construction site De Schelde in Vlissingen and design agency Nevesbu. For the first time stealth techniques were used in the design, such as the sloping walls of the bridge section. Much attention was also paid to the care and facilities for the crew, with more privacy and improved comfort.^[3]

The Karel Doorman class were designed as multi purpose frigates that could perform a wide range of missions. Their armament reflects this by incorporating many features, such as the ability to engage submarines, aircraft and surface vessels.^[4] Besides warfare the armaments can also be used to support anti-drug and piracy operations.

First amongst this class to be launched was HNLMS Karel Doorman. Laid down in February 1985 and launched in April 1988, it was commissioned by the Dutch navy in May 1991. Karel Doorman was followed by HNLMS Willem van der Zaan, HNLMS Tjerk Hiddes, HNLMS Van Amstel, HNLMS Abraham van der Hulst, HNLMS Van Nes, HNLMS Van Galen, and HNLMS Van Speijk. Even while the ships were still under construction, Dutch authorities tried, and ultimately failed, to negiotate purchase orders by interested foreign navies.^[5]

However, six decommissioned Karel Doorman-class frigates were eventually bought by the Belgian, Chilean, and Portuguese navies, and the proceeds were subsequently invested in development of the Holland-class offshore patrol vessel.

These multi-purpose frigates can be used in the anti-submarine, anti-aircraft, or surface combat roles. Their primary surface armament consists of two quad RGM-84 Harpoon anti-ship launchers with a range of up to 120 kilometres (75 mi). Also available is an OTO Melara 76 mm gun, which has both anti-ship and anti-air capabilities.

Air defence is provided by an AIM-7 Sparrow medium-range semi-active radar homing air-to-air missile with a range of up to 14 kilometres (8.7 mi) Sixteen VLS cells are mounted on the port external bulkhead of the hangar. The Goalkeeper close-in weapon system provides close-range air defence and can fire up to four thousand 30 millimetres (1.2 in) rounds per minute at a range of 200 to 3,000 metres (660 to 9,840 ft).

For anti submarine warfare, each ship is equipped with two twin torpedo launchers, firing Mark 46 torpedoes; and carries one NH-90 or Westland Lynx helicopter. The helicopter is also armed with 2 Mk 46 torpedoes, and carries dipping sonar and forward looking infrared systems.

The Royal Netherlands Navy and the Belgian Naval Component decided to upgrade the four frigates by rebuilding both hangar and helicopter deck for the NH-90 helicopter as well to replace the forward mast for fitting the new Thales SeaWatcher 100 phased array surface search radar and Gatekeeper electro-optical surveillance system. The first ship to receive the upgrade was Van Speijk in April 2012, next was Leopold I, followed by Van Amstel and Louise Marie is currently undergoing the modernization. SMART-S 3D search radars will not be replaced by SMART-S MK2.

Seawatcher 100 is a non-rotating active phased array radar for naval surface surveillance. The system automatically detects and tracks asymmetric threats and very small objects such as swimmers and periscopes in all weather conditions. Seastar can also be used for helicopter guidance. Seastar is internationally marketed as Sea Watcher 100

Gatekeeper is a 360-degree panoramic electro-optical surveillance and alerter system based on IR/TV technology. Designed to counter emerging asymmetric threats down to small boats and swimmers, Gatekeeper increases short-range situational awareness in littoral environments.

In 2018 the Portuguese Navy decided to modernize its two Karel Doorman-class frigates (Mid-life update), the first frigate started modernization in 2018 and was delivered in September 2021,^[7] the second frigate started modernization in 2020 and was received in October 2022.^[8]

The two multipurpose M-frigates which are still in service with the Royal Netherlands Navy are reaching the end of their life; they were designed to last until 2018/2023. Because of this the Dutch Ministry of Defence started design studies in 2013. The new frigates are again planned to fulfill a general purpose role with anti-submarine warfare as its specialty. However, since the Netherlands Royal Navy only owns six frigates in total by 2017, the new ships have to be able to perform well in all areas of the spectrum. This means that anti-air equipment also has to be present, in the form of VLS (vertical launch)-cells carrying Standard Missile 2 or ESSM-projectiles. Due to budget cuts, the replacement program was delayed and is now projected to deliver the first ships in 2028–29.

• List of naval ship classes in service