German Type U 66 Submarine

German Type U 66 Submarine

The Type U 66 was a class of five submarines or U-boats operated by the German Imperial Navy (German: Kaiserliche Marine) during World War I. The class is alternately referred to as the U-66-class or the Type UD. The class was built by Germaniawerft of Kiel to their 506d design as the U-7-class for the Austro-Hungarian Navy. The five boats were sold to the Imperial Germany Navy at the beginning of World War I when it was thought impossible for the submarines to reach the Mediterranean for delivery to Austria-Hungary.

The Austro-Hungarian Navy, after competitively evaluating six submarines of three foreign designs, selected the Germaniwerft 506d or Type UD design over a design from Whitehead & Co. for the U-7 class. The boats, numbered U-7 to U-11, were designed to be 228 feet (69 m) long and displace between 695 and 885 tonnes (766 and 976 short tons) when surfaced and submerged. They were to be armed with five torpedo tubes and a deck gun. For propulsion the design called for twin diesel engines for surface running and twin electric motors for subsurface movement. The Austro-Hungarian Navy ordered the boats in February 1913 and construction began on the first boats in November.

After the outbreak of World War I in August 1914, the Austro-Hungarian Navy became convinced that delivery of the still-unfinished submarines to the Mediterranean via Gibraltar would be impossible. As a result, they sold the five boats to the Imperial German Navy in November 1914. The German Navy assigned the numbers U-66 to U-70 to the five submarines and had them redesigned and reconstructed to their specifications. These changes, which included a larger deck gun, increased the displacement of the U-boats by almost 100 tonnes (110 short tons) surfaced and nearly 50 tonnes (55 short tons) submerged.

All five boats saw active service, and four sank 18 or more ships. Only U-68, sunk six days into her first war patrol in March 1916, had no successes. Two other boats, U-66 and U-69 disappeared in 1917. The remaining two U-boats, U-67 and U-70, were surrendered to the United Kingdom and were broken up by 1921.