Sperrbrecher M 32 Mur

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    invisible officer

    Again a bigger scratch 1/300 project, a Sperrbrecher.

    The Sperrbrecher was not unique to Kriegsmarine but no other navy used them in such extent. The birth year was 1903. A commission under Vizeadmiral von Tirpitz was ordered to present ideas to protect the Hochseeflotte from sea mines.

    The report includes the first naming of Sperrbrecher. Naval dictionaries translate it with barrier breaking vessel but most English books just use Sperrbrecher because that ship type is seen to be as German as Kindergarten.

    The idea was simple. A merchant vessel would steam in front of the battleships and explode the mines. It was to be filled with sand ballast, fascines and a large number of casks to keep it afloat. In WW I devices got developed to protect the bow. Cutting the cables of mines and getting them away from hull contact was the only protection in WW I. Not all worked well.

    Other towed devices added size to the cleared way, up to some 50 meter and 20 m depth.
    In 1918 the RN started to use magnetic mines without much effect. At armistice no clearing device was ready.

    WW II Sperrbrecher started with little alterations in 1939. The bow protection was now the Otter device. In the 30’s towed cables are developed to fight magnetic mines. These reacted on the metal ship’s magnetic field and so a towing vessel would be blown up if it ran over a mine. RN developed the degaussing to reduce the field. That worked well, but the wiping had to be done again and again because the ship’s field came back. And the later fuses reacted on wiped hull too.

    1940 saw the only larger use of Sperrbrecher type vessels by RN, the Mine Destructor Vessels. 10 got converted but sooon used as ordinary merchants.
    Kriegsmarine met the first British magnetic mines at the end of 1939 and soon the VES Sperrbrecher became the answer. Voraus Eigen Schutz was a gigantic electric magnet. A copper cable was slung behind the bow around the hull some 100 times. Up to 6000 meter! Inside was an iron core of up to 2000 tons!

    It produced a very strong field that exploded the 140 mines some 100 meter before the Sperrbrecher. RN reacted with an anti Sperrberecher mine with a very blunt fuze that only reacted to a super strong field. Exploding under the Sperrbreche. Kriegsmarine countered that with the Umpolvorrichtung that changed the poles every 10 seconds.

    Another special fuse was activated by a strong field but not exploded. Only a smaller following it exploded it, normally caused by an escorted vessel. A similar combined a magnetic sharpening with an acoustic impulse in the next 15 minutes.
    Germans and Allies used Acoustic mines and Sperrbrecher had to get devices to counter them by producing sounds in front of vessel.

    And the Kriegsmarine developed pressure-activated mines that had been much harder to counter.
    To tell about the myriad of changes in fuses and counter measures would fill a book.

    The Sperrbrecher had high losses. Some 50 % are lost in action, many by mines but late war more to air attacks. To counter that the Flak was much increased. The small German convoys benefitted from that.

    The typical formation was with the VES Sperrbrecher in front, 300 meter before next ship. The magnetic field would damage compass and other sensible stuff. Two M boats abreast followed, mine searching and giving AA cover. Then the escorted vessels followed. In most convoys one to five vessels. And behind them the bigger escorts (Zerstörer, Torpedobbote or more Minensucher) followed in a line.

    invisible officer

    The model is totally scratch built. Sperrbrecher 32 Mur was rated as one of the best designed Sperrbrecher. That was possible because it was still building at time of being taken over. It was one of many built for Norddeutschen Lloyd by Deschimag in Bremen. All had river names. 14,2 kts, 3290 BRT

    It was finished in October 1943 with all the latest devices. Including 2 x 10,5 cm guns, 2x 3,7 cm in twin mounting, 2 x 4 cm quads and 7x 2 cm. In addition RAG (Raketenabwurfgerät) rocket lauchers got fitted. It could fire HE rockets and chute/steel cable ones. A mix was fired, no Sperrbrecher downed a plane with them but the planes kept distance.

    Being the most modern Sperrbrecher Mur was sent to the hotspot. It was much needed for submarine escort in Biskaya. For that it had to pass the Channel. 29.1.1944 it went through the Dover Calais area. It was escorted by M292 and M 370 (both type 1940) and R-Boote from 2nd and 4th Flotilla. Former French escorts PA 2 and PA 3 got added.

    The dance started with MTB attacks at dawn. Next came radar controlled long range coastal artillery from Dover area. And then air attacks. A group from B-Dienst was on ship, getting informations from British wireless. The coastal radar was countered by metal foil
    Next morning saw all German vessels still afloat. Mur alone had 190 holes, 2 dead and two badly wounded.

    The Sperrbrecher had been very successful in escorting U-Boote. In more than 3500 missions just one submarine was lost by a mine.
    D-Day cut the area of BSW (Befehlshaber Sicherung West) in two. The Diesel engine Mur had to reduce the missions due to Diesel shortages in Western France. Coal burning Sperrbrecher took over.

    26.8.1944 Mur was decommissioned at St. Nazaire. The VES and arms got taken away for use on land. A conversion to Hospital ship with 600 beds was started. It was registered with International Red Cross as München. The large numbers of wounded made hospital ships a must.

    Another former Sperrbrecher, the Rostock, had been converted first. The officers and crew had been from merchant navy and everything was done according to international law to make it into a legal hospital ship. 19.9.44 it left Lorient for Spain with 211 wounded. Staff included 11 nurses. But MTB 696 and 713 approached the vessel and forced it to go to Portsmouth. A series of protests by Germany, Spain, some Neutrals and the USA (!) followed but Rostock was not set free. The RN claimed it to be a secret warship.

    Following that the München / Mur stayed at St. Nazaire, painted white with red crosses.
    It survived the war with some damage from air attacks on the harbor and became French booty.

    The French navy first used it as troop carrier. 1958 it was converted and became Île d’Oléron, used as experimental rocket ship. In that role it served for decades

    invisible officer

    And the usual building shot

    Charge The Guns

    Fascinating history and a great build. Another very useful scenario idea.

    Henry Higgins

    what a lovely model. you are very talented

    Paul G. Overend

    Lovely model and can see some good scenarios using that vessel.

    invisible officer

    Thank you all.

    I love building so I have a lot of fun doing scratch building.

    Well, the Sperrbrecher will be more often used with our own rule set. That includes a working system to create the ship data.

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