Tripartite-class minehunter

The Tripartite class is a class of minehunters developed from an agreement between the navies of Belgium, France and the Netherlands. A total of 35 ships were constructed for the three navies. The class was constructed in the 1980s–1990s in all three countries, using a mix of minehunting, electrical and propulsion systems from the three member nations. In France, where they are known as the Éridan class they are primarily used as minehunters, but have been used for minesweeping and ammunition transport in Belgium and the Netherlands. In the Netherlands, the Tripartites are known as the '.
In 1992, the Pakistan Navy acquired three vessels from France, one that was already built, one to be built in France and one built in France and Pakistan. Known as the Munsif class, all three are still in service. The Indonesian Navy acquired two minehunters in the 1990s from the Dutch to a modified design. Known as the Pulau Rengat class', the two ships are still in service. In 1997, France purchased three of the Belgian vessels. In 2007, the Latvian Naval Forces acquired five ships from the Netherlands which had been taken out of service at the beginning of the decade. The Bulgarian Navy acquired a former Belgian minehunter in 2007. The Netherlands and Belgium had a competition in 2018 to build a replacement class for their Tripartite/Alkmaar-class ships.

Design and development

A joint venture of the navies of France, Belgium, and the Netherlands, the Tripartite class of minehunters were a follow on design to the French s. All three nations would build their own hulls while each country was responsible for a different aspect of the vessels; France provided the minehunting and electronic systems, the Netherlands provided the main propulsion systems and Belgium supplied the minehunting propulsion system as well as the electrical generating systems. Each country intended to order 15 of the vessels, with Belgium's initial order being 10 with the option of 5 more. However, France cut their initial order to ten due to budgetary reasons.

Ships

France

In France the class is known as the Éridan class. Each hull was created from fibreglass, moulded in a steel shell. The hulls were long overall with a beam of and a draught of. The ships had a standard displacement of and at full load. This later increased to at full load. A container can be stored aboard the ships for additional supply room. The minehunters had an initial complement of 55, this was later reduced to 49.
The Éridan-class minehunters have two independent propulsion systems. In normal operations the minehunters are powered by a Brons-Werkspoor A-RUB 215V-12 diesel engine turning one shaft with a LIPS controllable pitch propeller. Using the conventional system, the minehunters have a maximum speed of and a range of at. For use when minehunting the vessels have two ACEC active rudders and a bow thruster. These are energised by three Astazou IVB gas turbine alternators rated at 150 kW. A fourth diesel-driven alternator rated at 160 kW supplies power during normal operations. Both systems can be operated from the bridge or from a soundproof control centre above the main deck. The maximum speed using the minehunting propulsion system that can be achieved is.
The minehunters were equipped with DUBM 21B sonar that could detect and classify ground and moored mines to a range of. The sonar was retracted during normal operations. The vessel was also equipped with Racal Decca 1229 radar. The vessels carried two ECA PAP 104 remotely operated underwater vehicles. In 2001, the minesweepers underwent modernisation and the sonar was replaced with the TUS 2022 Mk III type, the radar with the Bridgemaster E250 type and a TSM 2061 combat data system and a Bofors Double Eagle Mk2 ROV were fitted.
The Éridan class is armed with one 20 mm modèle F2 gun capable of firing 720 rounds per minute to a range of. The minehunters also mount one machine gun and two machine guns. The French vessels have limited minesweeping ability and were initially only fitted with mechanical sweep gear. In 1985, the Éridan class received AP4 acoustic sweep gear.
The initial order of ten was constructed for the French Navy in the 1980s by the Arsenal de Lorient. After the sale of Sagittaire to Pakistan in 1992, a replacement hull bearing the same name and hull number was constructed. Three Belgian versions of the class were acquired between March and August 1997.

Belgium

Originally ten ships were ordered for the Belgian Navy, with the option for five more that was never activated. The Polyship consortium was organised to direct the building programme, however the consortium was dissolved, leading to delays in the construction of the minehunters. This led to the vessels being reordered this time from Béliard Shipyard, which constructed the hulls at their yard in Ostend, Belgium before completing the minehunters at Rupelmonde. Differences between the Belgian and French versions of the class include a smaller displacement at standard and at full load. They are equipped with an Atlas Elektronik IMCMS combat data system. When minehunting, the Belgian vessels carry six divers and can have a portable decompression chamber installed abaft the forecastle break.
All vessels in the class are named after flowers and are thus sometimes called the "Flower" or Aster class. In 2001 the remaining Belgian minehunters had their engines upgraded. All remaining Belgian vessels have undergone an extensive upgrade during 2004–2008 involving replacement of the anti-mine warfare equipment. This included receiving the same sonar package as the French versions. The complement of the Belgian ships varies between 33 and 46 depending on mission.
In 1993, three of the vessels were paid off and laid up until being sold in 1997 to France. Crocus was modified into an ammunition transfer vessel the same year. Myosotis was converted to an ammunition transport before being taken out of service in 2004 and was sold to Bulgaria in 2009.

Pennant no.	Name	Builder		Launched	Commissioned	Status
M 915		Béliard Shipyard, Ostend and Rupelmonde, Belgium	24 February 1983	6 June 1985	16 December 1985	Sold to Pakistan in 2018
M 916		Béliard Shipyard, Ostend and Rupelmonde, Belgium	15 February 1984	14 February 1986	13 August 1986	To be donated to Bulgaria
M 917		Béliard Shipyard, Ostend and Rupelmonde, Belgium	15 October 1984	5 September 1986	5 July 1987	To be donated to Bulgaria
M 918		Béliard Shipyard, Ostend and Rupelmonde, Belgium	17 April 1985	26 February 1987	14 August 1987	Laid up 1993, sold to France 1997
M 919		Béliard Shipyard, Ostend and Rupelmonde, Belgium	28 October 1985	23 October 1987	18 February 1988	Laid up 1993, sold to France 1997
M 920		Béliard Shipyard, Ostend and Rupelmonde, Belgium	20 May 1986	21 June 1987	6 October 1988	Laid up 1993, sold to France 1997
M 921		Béliard Shipyard, Ostend and Rupelmonde, Belgium	27 November 1986	25 February 1988	8 July 1989	To be donated to Bulgaria
M 922		Béliard Shipyard, Ostend and Rupelmonde, Belgium	6 July 1987	4 August 1988	14 December 1989	Converted to ammunition transport. Taken out of service in 2004 and sold to Bulgaria in 2009.
M 923		Béliard Shipyard, Ostend and Rupelmonde, Belgium	22 February 1988	30 March 1990	27 September 1990	Gifted to Ukraine in 2025, renamed to Mariupol.
M 924		Béliard Shipyard, Ostend and Rupelmonde, Belgium	7 November 1988	17 December 1990	29 May 1991	To be donated to Bulgaria

Netherlands

In the Royal Netherlands Navy, the Tripartites are known as the. The Alkmaars were originally of similar design to the Belgian and French versions, with a standard displacement of and at full load. The displacement later increased to standard and at full load and then standard and at full load. The 20 mm gun that was initially mounted was removed, leaving only three 12.7 mm machine guns. Beginning in 2003, the remaining Dutch Alkmaar-class minehunters were upgraded with improved electronics, including Atlas Elektronik INCMS combat data system, Thales 2022 Mk III hull-mounted sonar, Atlas Seafox Mine Identification and Disposal System and a Double Eagle Mk III Mod 1 ROV.
The minehunters were constructed at the Van der Giessen-de-Noord yard in Amsterdam, a specially constructed site completed in 1978. Middelburg and Hellevoetsluis were optioned by Egypt, but due to financial issues, were instead completed for the Royal Netherlands Navy. Two ships of a modified design were built for the Indonesian Navy which led to the delay of Vlaardingen and Willemstads construction.
In 2000, three ships were withdrawn from service, followed by two more in 2003. All five were sold to Latvia with handovers beginning in 2007. Four more ships, were decommissioned in 2011 following a series of deep budget cuts to the navy. Two of them were sold to Bulgaria in 2019. In 2021 it was indicated that a further two ships would be sold to Pakistan. Haarlem and Middelburg were transported via a heavy-lift ship to Pakistan in late 2022.
, the Netherlands is planning to transfer two Alkmaar-class ships to Ukraine in 2025. The vessels would be used to clear mines dropped into the Black Sea during Russia's invasion of Ukraine.

Pennant no.	Name	Builder		Launched	Commissioned	Status
M 850		Van der Giessen-de-Noord, Alblasserdam, Netherlands	30 January 1979	18 May 1982	28 May 1983	Decommissioned in 2000, sold to Latvia
M 851		Van der Giessen-de-Noord, Alblasserdam, Netherlands	29 May 1980	29 October 1982	17 August 1983	Decommissioned in 2000, sold to Latvia
M 852		Van der Giessen-de-Noord, Alblasserdam, Netherlands	5 January 1981	26 February 1983	16 November 1983	Decommissioned in 2000, sold to Latvia
M 853		Van der Giessen-de-Noord, Alblasserdam, Netherlands	16 June 1981	6 May 1983	12 June 1984	Decommissioned in 2011, sold to Pakistan
M 854		Van der Giessen-de-Noord, Alblasserdam, Netherlands	30 November 1981	9 July 1983	12 April 1984	Decommissioned 2003, sold to Latvia
M 855		Van der Giessen-de-Noord, Alblasserdam, Netherlands	24 May 1982	2 December 1983	18 July 1984	Decommissioned 2003, sold to Latvia
M 856		Van der Giessen-de-Noord, Alblasserdam, Netherlands	7 November 1982	5 May 1984	12 December 1984	Decommissioned in 2011, sold to Bulgaria
M 857		Van der Giessen-de-Noord, Alblasserdam, Netherlands	25 February 1983	27 September 1984	13 May 1985	Decommissioned in 2024, donated to Ukraine in 2025, renamed Henichesk
M 858		Van der Giessen-de-Noord, Alblasserdam, Netherlands	11 July 1983	23 February 1985	10 December 1986	Decommissioned in 2011, sold to Pakistan
M 859		Van der Giessen-de-Noord, Alblasserdam, Netherlands	12 December 1983	18 July 1985	20 February 1987	Decommissioned in 2011, sold to Bulgaria
M 860		Van der Giessen-de-Noord, Alblasserdam, Netherlands	6 May 1984	20 December 1985	9 July 1986	to be donated to Bulgaria in 2027-2028
M 861		Van der Giessen-de-Noord, Alblasserdam, Netherlands	1 October 1984	2 May 1986	10 December 1986	Decommissioned in 2022 use for spare parts
M 862		Van der Giessen-de-Noord, Alblasserdam, Netherlands	25 February 1985	4 October 1986	7 May 1987	to be donated to Bulgaria in 2027-2028
M 863		Van der Giessen-de-Noord, Alblasserdam, Netherlands	6 May 1986	4 August 1988	15 March 1989	Decommissioned in 2024, donated to Ukraine in 2025, renamed Melitopol
M 864		Van der Giessen-de-Noord, Alblasserdam, Netherlands	3 October 1986	27 January 1989	20 September 1989	to be donated to Bulgaria in 2027-2028