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The U boat 486 that killed Carl Ralph Bonde Jr.

February 11, 2013

 

Type VIIC German U-boat, such U-486, which sank the SS Leopoldville.

The Type VIIC was the workhorse of the German U-boat force, with 568 commissioned from 1940 to 1945.[73] The first VIIC boat commissioned was the U-69 in 1940. The Type VIIC was an effective fighting machine and was seen almost everywhere U-boats operated, although its range of only 6,500 nautical miles was not as great as that of the larger Type IX(11,000 nautical miles), severely limiting the time it could spend in the far reaches of the western and southern Atlantic without refueling from a tender or U-boat tanker.[73] The VIIC came into service toward the end of the first “Happy Time”[Note 6] near the beginning of the war and was still the most numerous type in service when Allied anti-submarine efforts finally defeated the U-boat campaign in late 1943 and 1944.[73]

Type VIIC differed from the VIIB only in the addition of an active sonar and a few minor mechanical improvements, making it 2 feet longer and 8 tons heavier. Speed and range were essentially the same. Many of these boats were fitted with snorkels in 1944 and 1945.[73]

They had the same torpedo tube arrangement as their predecessors, except for U-72, U-78, U-80, U-554, and U-555, which had only two bow tubes, and for U-203, U-331, U-351, U-401, U-431, and U-651, which had no stern tube.[73]

On the surface the boats (except for U-88, U-90 and U-132 to U-136 which used MAN M6V40/46s) were propelled by two supercharged Germaniawerft, 6 cylinder, 4-stroke M6V 40/46 diesels totaling 2,800 to 3,200 hp (2,100 to 2,400 kW) at 470 to 490 rpm.[73]

For submerged propulsion, several different electric motors were used. Early models used the VIIB configuration of two AEG GU 460/8-276 electric motors, totaling 750 hp (560 kW) with a max rpm of 296, while newer boats used two BBC (Brown Boveri & Co) GG UB 720/8, two GL (Garbe Lahmeyer) RP 137/c electric motors or two SSW (Siemens-Schuckert-Werke) GU 343/38-8 electric motors with the same power output as the AEG motors.[73]

Perhaps the most famous VIIC boat was U-96, featured in the movie Das Boot.[73]

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Torpedoes

The U-boats’ main weapon was the torpedo, though mines and deck guns (while surfaced) were also used. By the end of the war, almost 3,000 Allied ships (175 warships; 2,825 merchant ships) were sunk by U-boat torpedoes.[13] Early German World War II torpedoes were straight runners, as opposed to the homing and pattern-running torpedoes which were fielded later in the war. They were fitted with one of two types of pistol trigger: impact, which detonated the warhead upon contact with a solid object, and magnetic, which detonated upon sensing a change in the magnetic field within a few meters. One of the most effective uses of magnetic pistols would be to set the torpedo’s depth to just beneath the keel of the target. The explosion under the target’s keel would create a shock wave, and the ship could break in two. In this way, even large or heavily-armored ships could be sunk or disabled with a single well-placed hit. In practice, however, the depth-keeping equipment and magnetic and contact exploders were notoriously unreliable in the first eight months of the war. Torpedoes would often run at an improper depth, detonate prematurely, or fail to explode altogether—sometimes bouncing harmlessly off the hull of the target ship. This was most evident in Operation Weserübung, the invasion of Norway, where various skilled U-boat commanders failed to inflict damage on British transports and warships because of faulty torpedoes. The faults were largely due to a lack of testing. The magnetic detonator was sensitive to mechanical oscillations during the torpedo run and at high latitudes fluctuations in the Earth’s magnetic field. These were eventually phased out, and the depth-keeping problem was solved by early 1942.[14]

Later in the war, Germany developed an acoustic homing torpedo, the G7/T5. It was primarily designed to combat convoy escorts. The acoustic torpedo was designed to run straight to an arming distance of 400 meters and then turn toward the loudest noise detected. This sometimes ended up being the U-boat itself; their own homing torpedoes may have sunk at least two submarines. (Problems with steering mechanisms on normal torpedoes made them occasionally lethal to the firing boat as well). Additionally, it was found these torpedoes were only effective against ships moving at greater than 15 knots (28 km/h). At any rate, the Allies countered acoustic torpedoes with noisemaker decoys such as Foxer, FXR, CAT and Fanfare. The Germans, in-turn, countered this by introducing newer and upgraded versions of the acoustic torpedoes, like the late war G7es.

U-boats also adopted several types of “pattern-running” torpedoes which ran to a preset distance, then travelled in either a circular or ladder-like pattern. When fired at a convoy, this increased the probability of a hit if the weapon missed its primary target.

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