Karel Doorman-class

The Karel Doorman-class frigates, designated as multi-purpose vessels, were developed to replace the Roofdier-class frigates of the Royal Netherlands Navy. The Dutch government approved the project in 1977 under the "Noordzeefregat" program. The design was produced by the Royal Netherlands Navy in collaboration with the De Schelde shipyard and the Nevesbu design agency. A total of eight vessels were constructed by Damen Schelde Naval Shipbuilding between 1985 and 1995. The lead ship, HNLMS Karel Doorman, was commissioned in May 1991.

The class design incorporates stealth technology, specifically sloped surfaces in the bridge section to reduce radar cross-section. These vessels utilize a Combined Diesel or Gas (CODOG) propulsion system. As multi-purpose platforms, the ships are equipped for anti-submarine, anti-aircraft, and surface warfare roles. Primary armament includes Harpoon anti-ship missiles, Sea Sparrow anti-air missiles launched from vertical launch system (VLS) cells, an OTO Melara 76 mm gun, and a Goalkeeper close-in weapon system (CIWS). For anti-submarine operations, the frigates utilize twin torpedo launchers for Mark 46 torpedoes and a hangar facility for a single helicopter, such as the Westland Lynx or NH90 NFH.

The Royal Netherlands Navy originally operated all eight units. Between 2004 and 2010, six vessels were decommissioned and sold to international operators. Chile acquired two ships in 2004, followed by Belgium in 2005 and Portugal in 2006. Currently, the class is operated by the Royal Netherlands Navy, the Belgian Navy, the Chilean Navy, and the Portuguese Navy.

Modernization programs have been implemented to maintain operational standards. Dutch and Belgian units received upgrades including the Thales SeaWatcher 100 phased array radar, the Gatekeeper electro-optical surveillance system, and Low Frequency Active and Passive Sonar (LFAPS). These units also underwent structural modifications to the hangar and flight deck to accommodate the NH90 helicopter. The Portuguese Navy completed a mid-life update on its two vessels between 2018 and 2022, which included the acquisition of Harpoon Block II conversion kits. The remaining Dutch and Belgian vessels are scheduled for replacement by the Anti-Submarine Warfare Frigate (ASWF) class, with deliveries projected to begin in the late 2020s.