u-48 TYPE VII-B
Take a tour of the deadliest German submarine to prowl the seas
Despite the fact that unrestricted submarine warfare had brought the British Isles to near collapse during World War I, the German navy of World War II, the Kriegsmarine, had only 56 operational U-boats (Unterseebooten, or undersea boats) when the conflict erupted in September 1939.
Admiral Karl Dönitz, commander of the
U-boat service of the Kriegsmarine, realised the potential that a renewed blockade of the British Isles and a concerted effort to interdict transatlantic merchant shipping to the island nation held. If enough U-boats were constructed and deployed they would be able to strangle Britain into submission. Dönitz argued forcefully for a vigorous building programme and the launching of dozens more U-boats to help ensure the ultimate victory. However, when World War II began the Kriegsmarine was woefully short of his goal.
Nevertheless, German submarines indeed wrought significant damage on British shipping once again, and the development of a second generation of modern, sleek undersea hunters had been ongoing during the interwar years. The Type VII series of U-boats was completed in the greatest numbers, with just over 700 launched during roughly a decade of production from 1935-1945. Designated A, B and C, the Type VII U-boats menaced the sea lanes and were responsible for the sinking of millions of tons of Allied shipping.
The most successful submarine of World War II in terms of ships and tonnage sunk was the Type VII-B U-48, launched on 8 March 1939 and commissioned six weeks later. Already at sea when the conflict broke out, the U-48 survived a dozen war patrols under three commanders, served as a training boat and was sunk in the spring of 1945 during the last days of the war – not by enemy action, but scuttled by its own crew to prevent it from falling into Allied hands.
“IF ENOUGH U-BOATS WERE CONSTRUCTED AND DEPLOYED, THEY WOULD BE ABLE TO STRANGLE BRITAIN INTO SUBMISSION”
ENGINE
The pair of supercharged fourstroke, six-cylinder Germaniawerft F46 diesel engines that powered the U-48 while surfaced generated up to 3,160 shaft horsepower and a top speed of 17.9 knots. The engine was widely produced prior to and during World War II. While running submerged U-48 was capable of a top speed of eight knots with two AEG GU 460/8276 double acting electric motors producing 740 shaft horsepower. Diesel exhaust ports were mounted on the sides of the hull and designed to vent exhaust downward to minimise the submarine’s visibility on the surface.
“WHILE RUNNING SUBMERGED U-48 WAS CAPABLE OF A TOP SPEED OF EIGHT KNOTS”
ARMAMENT
Early in World War II the standard German torpedo was the G7A(TI), a variable-speed, steam-powered weapon that was controlled by a gyroscope. Speed was determined by preset pressure levels of 30, 40 or 44 knots. The 44-knot setting was used only by surface craft. A setting of 40 knots yielded a range of 7,500 metres (24,606 feet). The torpedo was armed with a warhead of 280 kilograms (617 pounds) of explosive. The Type VII-B was also capable of carrying and laying up to 39 mines. Secondary armament consisted of the 88mm SK C/35 deck gun and the 20mm C/30 antiaircraft gun.