Kortenaer-class frigate

The ''Kortenaer'' class was a class of anti-submarine frigates of the Royal Netherlands Navy. Like other frigate types of the 1970s and 1980s, they featured a COGOG (combined gas or gas) propulsion system with separate cruise and sprint gas turbines. Ten were built by de Schelde in Vlissingen and two by Wilton-Fijenoord in Schiedam between 1978 and 1982. Only ten served with the Royal Netherlands Navy: two were sold to Greece while still under construction and replaced by two frigates which were an anti-air warfare variant of the ''Kortenaer'' class. The Greek frigates were renamed the . After service with the Dutch ended, eight of the frigates were sold to Greece in 1992 and the remaining two to the United Arab Emirates. Three of the ships have since been retired from active military service with one converted into the superyacht .

Background

The ''Kortenaer'' class was designed as an anti-submarine warfare (ASW) frigate intended to replace the two ASW classes ( and es) already in service with the Royal Netherlands Navy. However, the Dutch planning committee intended for the class to have the maximum amount of similar systems to other NATO frigate classes, even offering to enter in agreements with other navies, such as the British Royal Navy. These offers were rejected and instead the Dutch designed a standard platform, later referred to as the "Standard design", that would allow for ASW and anti-air warfare (AAW) variants, while also conforming to NATO standards.

Design and description

The design's hull form was similar to contemporary French designs with continuous upper and main decks, a single rudder and a clipper bow. The frigates were designed to operate smoothly in seaways with reduced length-to-beam ratio than usual for ships of this size. Furthermore, the ships would have a higher degree of automation to reduce the number of engine room complement required and overall, with the frigates being able to be operated and fought from the operations room. The ''Kortenaer'' class as built were long overall with a beam of and a draught of at the hull and at the base of the propeller. As built the frigates had a standard displacement of and at full load. With varying gun and radar compositions of the ships over their careers, the displacement would later differ among the class. Due to the high amount of automation within the ship, the complement was reduced from 196 to 176 officers and sailors.

The ''Kortenaer'' class sported 15 watertight bulkheads. The vessels were powered by a combined gas or gas (COGOG) system incorporating two Rolls-Royce Tyne RM1C gas turbines creating each and Rolls-Royce Olympus TM3B gas turbines creating each. These drove two LIPS controllable pitch propellers giving the ship a maximum speed of and a cruising speed of . The vessels had a range of at while using a single Tyne turbine. Electricity was provided by four SEMT-Pielstick PA4 750 kW diesel generators. The vessels also had redundancy in their design, being equipped with two auxiliary boilers and evaporators. The engineering plant was spread over four compartments. Moving forward to aft the plant was situated as follows; auxiliaries, Olympus turbines, Tyne turbines and reduction gear, and auxiliaries. To increase stability, the vessels mounted a pair of Denny–Brown fin stabilizers.

The design originally called for the installation of two OTO Melara /62 calibre naval guns in single mounts, with one place forward and one mounted atop the hangar aft. However, after the first four ships, the aft 76 mm gun was swapped out for a Bofors /L70 calibre anti-aircraft (AA) gun. The 76 mm guns could fire a shell to a range of at 85 degrees elevation. The aft guns were later replaced in all ships with a single-mounted, seven-barrelled SGE-30 Goalkeeper close-in weapons system (CIWS) that had a range of .

All the vessels mounted two quad launchers for Harpoon anti-ship missiles, each missile capable of travelling at 0.9 Mach carrying a warhead. They were also armed with a Mark 29 octuple launcher for the Sea Sparrow AA missile and could embark up to 24 missiles. The Sea Sparrow had a range of at a speed of 2.5 Mach with a warhead. Additionally the frigates were equipped with two twin-mounted Mk 32 torpedo tubes for Mk 46 Mod 5 torpedoes that had a range of at with a warhead.

The ''Kortenaer'' class was initially equipped with Knebworth/Corvus rocket-launched chaff system, replaced by SRBOC six-tubed chaff launchers. They sported an ESM/ECM Ramses jammer and a SEWACO II action data system. They utilised LW 08 air search radar operating on the D band, ZW 06 surface search radar operating on the I band and STIR and WM 25 fire control radars operating on the I/ J bands. For ASW purposes, the frigates had bow-mounted SQS-505, SQS-509 sonar or SQR-19 TACTASS towed sonar. The ''Kortenaer'' class had a flight deck and hangar at the stern of the ship that was initially capable of operating up to two Westland SH-14B Lynx helicopters, but normally carried only one during peacetime operations.

Construction and service

The Dutch ordered the first batch of four ships on 31 August 1974. This was followed by a second batch of four on 28 November 1974 and a third batch of four on 29 December 1976. The first eight ships were all constructed by Royal Schelde. The ninth and tenth ships were built by Wilton-Fijenoord, and the final two ships were constructed by Royal Schelde. A contract was signed on 15 September 1980 with Greece for the sale of one the hulls under construction and the option for one more, which was taken up on 7 June 1981. These turned into hulls six and seven of the second batch (''Peter Florisz'' and ''Witte de With''). The remaining ''Kortenaer''-class ships were initially used to patrol areas of the Atlantic Ocean but in the 1990s, their operations were shifted to the Mediterranean Sea and Strait of Hormuz. This was highlighted by NATO deployments in support of blockade operations during the Yugoslav Wars and operations in the Strait of Hormuz and Persian Gulf during the Gulf War. In 1993, ''Bloys van Treslong'' was sent west to the Caribbean Sea to enforce a United Nations blockade of Haiti. In 2001, the ''Kortenaer''s saw one last mission in Dutch service, with ''Philips van Almonde'' deploying to the Persian Gulf as part of Operation Enduring Freedom. However, budget cuts to the military began and forced the early retirement of the class in Dutch service.

On 9 November 1992, Greece signed an agreement to acquire more ships of the class, with the initial group totalling three. ''Banckert'', ''Callenburgh'' and ''Van Kinsbergen'' were the first three to be sold. This was followed by ''Kortenaer'', the second ''Peter Florisz'', ''Jan van Brakel'', ''Philips van Almonde'' and ''Bloys van Treslong''. The remaining two frigates were transferred to the United Arab Emirates in a contract signed on 2 April 1996 following a refit at Royal Schelde.

Ships in the class

The ships were named after Dutch captains and admirals:

Export

Greece

The first two frigates were acquired in 1980 and entered service with the Hellenic Navy in 1981 and 1892. Named ''Elli'' and ''Limnos'' construction of a third ship, to be built in Greece, was cancelled. On the initial Greek ships, the 40 mm gun was never installed and instead of the Goalkeeper CIWS, two American Phalanx Mk 15 CIWS were installed instead, to either side of the aft 76 mm gun. Furthermore, the Hellenic Navy did not operate Lynx helicopters so the hangar was extended to accommodate two Agusta-Bell AB 212ASW helicopters. From 1993 to 1997 four more ''Kortenaer''-class frigates entered service with the Hellenic Navy and underwent the same modifications as ''Elli'' and ''Limnos'' with the exception of the lengthened hangars. From 2001 to 2003, the final four ships entered Greek service and were also modified like the others taken over from Dutch service. Six of the ships underwent an electronics refit from 2003 to 2006. The first of the Greek frigates was taken out of service in 2013.

Iran

The Imperial Iranian Navy was preparing to place an order with Royal Schelde but all military contracts were cancelled after the Iranian Revolution.

United Arab Emirates

Two ships were transferred to the United Arab Emirates military, entering service as ''Abu Dhabi'' and ''Al Emirat'' in December 1997 and May 1998 respectively. Based at Jebel Ali, the two frigates had additional air conditioning fitted, a new surface search radar (Signaal Scout using the I band) and operated two Eurocopter AS565 Panther helicopters. ''Al Emirat'' was later converted into a super luxury yacht known as in 2015. There were plans to convert ''Abu Dhabi'' into a superyacht as well.

See also

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* MEKO 140
* MEKO 360
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Citations

Bibliography

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Further reading

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External links

{{DEFAULTSORT:Kortenaer Class Frigate
Frigate classes
Frigates of the Royal Netherlands Navy
Kortenaer-class frigates