The main task of the minehunters is to keep the sea, coastal waters and harbour approaches free of mines. They also protect maritime units in areas where there are mines by conducting specific mine countermeasures operations.
The minehunters can be deployed anywhere in the world to provide support to land operations from the sea. But they can also operate closer to home, locating and clearing mines and other explosive ordnance at sea in the Dutch sector of the Continental Shelf.
Thanks to their special glass-reinforced polyester construction, minehunters produce very little sound and no magnetic field disturbance. They will not, therefore, set off a mine if they pass over it.
Crew 28 tot 38
Displacement 543 tonnes
Length 51.5 metres
Beam 8.9 metres
Draught 38 metres
Minehunting mode 2 ADEC azimuth thrusters, total 240 hp
Normal propulsion Stork Werkspoor 1860 hp
Speed 13 knots (normal propulsion)
Hull Mounted Sonar (HMS) TUS Mk 2022
Self Propelled Variable Depth Sonar (SPVDS) Saab/Bofors Double Eagle Mk III with TUS Mk 2022 sonar
C2 system ATLAS electronics Integrated Mine Counter Measures System (IMCMS)
Deck armament 3 x .50 machine guns
SeaFox Mine Identification and Disposal System (ATLAS)
Mine clearance divers
The size of the crew depends on the tasks to be carried out. The total size can vary between 28 and 38 crew members. Everyone on board has their own tasks and speciality. In addition, every crew member has a specific role in the event of, for instance, a fire or if the ship sustains damage. At all times, the crew is a single team, working closely together in a relatively small space, often under difficult circumstances.
The 6 minehunters of the Alkmaar class operated by the Royal Netherlands Navy are a joint design of the Netherlands, Belgium and France. France built the mine-hunting equipment, Belgium provided the electronics and the Netherlands constructed the propulsion train. To reflect the cooperation between the three countries, the international name of this class of ship is the Tripartite class.
As a cost-cutting measure, four minehunters were decommissioned in 2011. These were HNLMS Haarlem, HNLMS Maassluis, HNLMS Hellevoetsluis and HNLMS Middelburg.
The most striking aspect of a minehunter its non-ferrous construction. The hull is made of glass-reinforced polyester and the superstructure of aluminium. The reason for this is that most sea mines are triggered by disturbances in the magnetic field and this type of construction avoids such disturbances. The minehunters have been modernised as part of the Project Adjusting Mine countermeasures capability (PAM). The project involved upgrading the electronic sensors to improve the mine neutralisation capability.
The minehunters of the Royal Netherlands Navy can be equipped with two types of sonar, in all cases a Hull Mounted Sonar (HMS) and – depending on the mission profile – a Self Propelled Variable Depth Sonar (SPVDS), which allows the minehunters to search the seabed. This sonar equipment can detect not only mines, but also shipwrecks, containers washed overboard, etc.
Every minehunter has a wire-guided underwater vessel, the SeaFox C/I. If the crew suspect that they have found a mine with their sonar, they launch the SeaFox. The SeaFox is fitted with a video camera and a mine detonation charge. The video images are analysed on board. If the object is indeed a mine, the SeaFox C (Combat) is collided with the mine, setting off the build-in shaped charge. The SeaFox C is then destroyed together with the mine. The SeaFox I (Identification) does not carry a detonation charge, but is only used to identify the mine.