Videotour (3 Min.)

Welcome aboard!

The ex-HNLMS Mercuur is a former submarine support ship of the Royal Netherlands Navy. It was designed and built as an ocean minesweeper, as part of the US Navy Aggressive class wooden oceangoing minesweepers. It was therefore a warship that was neither designed for battle nor has it ever performed in that way. It has been a museum ship since 1993 and is now located in Vlissingen, in the heart of the Scheldekwartier, a new district that is built on the territory of the famous former Royal Schelde Shipyard.

American roots

The Mercuur was built in the United States in 1952-1954 and then given on loan to the Netherlands Navy as MSO 483 (MSO = Mine Sweeper Ocean). Together with 5 other sister ships she was part of the Mutual Defence Assistance Programme. Through this programme the United States helped European countries to rebuild their armed forces after the Second World War.

Made of wood!

You don’t immediately see it in a photo, but the Mercuur is built of wood. Most materials on board are made of wood, aluminum or designated non-magnetic materials. In those days minesweepers were built in this way to avoid danger when clearing magnetic mines. These mines lurk on the seabed for a change in the geomagnetic field caused by a passing metal ship and then explode. This was not always the case though, as some mines were programmed in such a way that they would let the first ships pass by, to explode near the third or tenth ship. This prevented the enemy from easily discovering and clearing these mine fields.

Hr.Ms. Onverschrokken 

At the time of the application, the ship was named Hr.Ms. Onverschrokken and given the name signal M886. Along with her five sister ships of the Onversaagd-class, she has never been active as a minesweeper though. Most of the time these ships were kept in conservation at the naval base of Den Helder. They were given a new purpose in 1965: as a headquarters and support ship for minesweeping flotillas, as a hydrographic survey vessel or – as in the case of the Mercuur – as a torpedo of submarine support ship.

New life as a support ship Mercuur

The ship was converted into a torpedo or submarine support ship in 1972. For that purpose a large crane was installed on board in order to recover used exercise torpedoes out of the water. The ship supported Dutch submarines and often joined them in English and Norwegian waters. When a submarine had launched exercise torpedoes, these floated to the surface at the end of their run. It was the task of the Mercuur to recover these and prepare for reuse. Following the conversion to torpedo support ship, she was also given a new name: Hr.Ms. Mercuur. That was no coincidence: It is by Dutch naval tradition that every torpedo supportship bears this name. The name signal also changed from M886 to A856. The M stood for Minesweeper, the A for Auxiliary.

Saved from demolition – three times is a charm

After her decommissioning in 1987, the Mercuur was saved from demolition by an initiative in Amsterdam, that received her on loan from the navy. This didn’t turn out to be a success. Therefore it was transferred to the Stichting Behoud Maritieme Middelen at Scheveningen (a seaside suburb of The Hague) in 1993, which converted her into a proper museum ship in Scheveningen until 2015. Demolition loomed when asbestos was detected, until the Stichting Behoud Maritiem Erfgoed (Maritime Heritage Foundation) in Vlissingen succeeded in saving her. 

Museum ship in Vlissingen

The Mercuur came to Vlissingen in August 2017. After a major overhaul – during which it was made completely asbestos-free on behalf of the Dutch Navy Authorities – it was officially transferred to our foundation by the Dutch navy. Since then, an enormous amount of work has been done to refurbish the ship and to again convert it into a museum ship. We are proud of all our sponsors, donors and volunteers who give our old lady a new future. 


Onverschrokken (1954-1972), Mercuur (1972-1987)

Builder: Peterson Builders, Inc., Sturgeon Bay, Wisconsin, United States

Yard number: MSO 483

Laid down: 16 February 1952

Launched: 17 February 1953

Acquired: 22 July 1953

Commissioned: 22 June 1954  11 May 1973

Decommissioned: 1 March 1973   12 February 1987

Identification: M886 (1954-1965), A856 (1965-1987)

General characteristics

Type: Minesweeper (1954-1965)

Torpedo support ship (1972-1987)

Displacement: 790 ton

Length: 53 m (173 ft 11 in)

Beam: 10.7 m (35 ft 1 in)

Draught: 3.2 m (10 ft 6 in)

Propulsion: 1600 hp

Speed: 14 knots (26 km/h; 16 mph)

Complement: 65

Armament: 1x 40 mm machine gun