Mine countermeasures in the Great Belt  

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Museums don’t usually occupy themselves with modern affairs and events. However, we believe that, in connection with our exhibition of sea-mines, it would be a good idea to inform our visitors of what it actually means to dispose of all these types of mines on the sea bottom. The removal of large amounts of explosives isn’t specifically a Danish problem, but rather an international one.  

When the Museum of the Cold War “Langelandsfort” opened its exhibition on sea mines, it received an invitation from the Danish Navy to accompany one of its ships during mine disposal operations in the Great Belt. The ship in question was the mine countermeasures (MCM) vessel MS D5 “Hirsholm”, in co-operation with MSF 4, under the command of MCM Kaptajnløjtnant Andreas Johansen.


The museum was represented by the former oversergent Filip Nielsen, who formerly served with the Danish Navy’s frogman corps and who is familiar with the former MCM-service. 

The ship left the harbour of Bagenkop at 06.30 hrs. and sailed in the direction of the southern Great Belt (Langelandsbelt), where it arrived approximately one hour later. MS D5 “Hirsholm” is equipped with a remotely operated underwater robot (ROV) of the “Double Eagle MK IIS class, which has been built for reconnaissance of the bottom of the sea.  The operator, who is situated on the bridge, manoeuvres the ROV by means of a cable, which also returns sonar- and closed circuit video images to the ship                               


When an object is located, the crew determines whether it is a sea mine or, as is usually the case, just  a large stone. Both the ship and the drone are manoeuvered with a stunning precision, whithout ever letting the level of concentration down.


For hours on end, scores of objects on the sea bottom are observed and frequently determined to be stones. A certain monotony sets in. But then, suddenly, a shape appears on the monitor. The drone is manoeuvered into a different position and there it is, a second world war sea-mine, dark and misterious.


“It is a British MK 1-IV, dropped from an aircraft during the Second World War, three hundred kilos of explosives”, remarks the operator. Its position, 54.41,6 N – 010.48,2 E, and some other relevant information are entered into the computer. “This is our 26th of this year”, says the MCM-officer.


All positions had previously been determined by means of a remotely controlled drone (MSF), which towed a side-scan sonar behind it. The sonar takes photos of the sea bottom, which are later determined by the experts on “Hirsholm”. The “interesting” objects merit being inspected more closely by the underwater robot.

  Mine chart of the waters near  Langelandsfort        A photo of a mine, found by the de side-scan sonar    

After a long day of close-up inspections, the underwater robot is hoisted back on deck, in order to prepare it for the demolition work. An explosive device, containing a 30 kilo’s explosive charge with an electric detonator, is attached to the underside of the drone.


Then the ROV is directed back to the mine, where it drops its charge exactly next to the mine. Then it is again hoisted back on deck. The commanding officer informs all shipping traffic that an underwater explosion will take place in such and such a position. After the order to detonate has been given, two undersea explosions are heard and the surface of the sea explodes.


Afterwards, the crew gathers in the mess where the traditional detonation cake and a cup of coffee are issued. Then the ship is cleared for its return journey to Bagenkop harbour.


Disposing of all these explosives is a time-consuming process, which is being executed in the Danish waters. But unfortunately it is necessary work. Denmark has two MCM-units, which are active all year round, searching for sea mines in the Danish territorial waters. Their crews belong to MCM Danmark, the Danish mine countermeasures service. Denmark also has international obligations to clear sea mines.


In 2013, these units will travel to the Baltic Area. Not only to clear mines, but also to take part in exercises with other international mine countermeasures services.


The photographs of computer monitors are property of MCM Danmark.
The other photographs are property of Langelands Museum.


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